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C / North , state Library ^ North Carolina Department op Conservation and Development Hargrove Bowles, Jr., Director Division of Mineral Resources Jasper L. Stuckey, State Geologist Bulletin 76 Geology and Mineral Resources of Moore County, North Carolina By James F. Conley Raleigh 1962 North Carolina Department of Conservation and Development Hargrove Bowles, Jr., Director Division of Mineral Resources Jasper L. Stuckey, State Geologist Bulletin 76 Geology and Mineral Resources of Moore County, North Carolina By James F. Conley Raleigh 1962 . Members of the Board of Conservation and Development Governor Terry Sanford, Chairman Raleigh R. Walker Martin, Vice Chairman Raleigh John M. Akers Gastonia Dr. Mott P. Blair Siler City Robert E. Bryan : Goldsboro Mrs. B. F. Bullard . Raleigh Daniel D. Cameron : . Wilmington Mrs. Fred Y. Campbell r Waynesville Dr. John Dees I Burgaw William P. Elliott, Sr Marion E. Hervey Evans, Jr Laurinburg E. R. Evans Ahoskie E. D. Gaskins Monroe Andrew Gennett Asheville Luther W. Gurkin, Jr Plymouth Woody R. Hampton , Sylva Charles E. Hayworth , High Point Gordon C. Hunter ___.__Roxboro Roger P. Kavenagh, Jr ... Greensboro Carl G. McGraw Charlotte Lorimer W. Midgett Elizabeth City Ernest E. Parker, Jr Southport R. A. Pool .' Clinton Eric W. Rodgers : Scotland Neck Robert W. Scott Haw River W. Eugene Simmons Tarboro James A. Singleton Red Springs J. Bernard Stein Fayetteville Charles B. Wade, Jr Winston-Salem 11 Letter of Transmittal Raleigh, North Carolina May 2, 1962 To His Excellency, Honorable Terry Sanford Governor of North Carolina Sir: I have the honor to submit herewith manuscript for publica-tion as Bulletin 76, "Geology and Mineral Resources of Moore County, North Carolina", by James F. Conley. This report contains the results of detailed investigations of the geology and mineral resources of Moore County and should be of value to those interested in the geology and mineral re-sources of Moore County and adjacent areas. Respectfully submitted, Hargrove Bowles, Jr. Director in Contents Page Introduction 1 Location and area 1 Purpose and scope 1 Geography ^ 1 Culture 1 Climate 1 Physiography 2 Topography 2 Drainage 2 9> Geology - 2 The Carolina Slate Belt 2 Stratigraphy 3 Lower volcanic sequence 4 Felsic tuffs and flows - 4 Mafic tuffs 4 Andesite tuffs 5 Volcanic-sedimentary sequence 6 Slates 6 Environment of deposition 6 Structure 7 Folds 7 Troy anticlinorium 7 Minor folds 7 Faults 7 Longitudinal faults 7 Glendon fault 7 Robbins fault 8 Other longitudinal faults 8 Cross faults 8 iv Page The Deep River Triassic Basin 8 Stratigraphy 9 Pekin formation 9 Cumnock formation 9 Sanford formation 10 Unnamed upper conglomerate 10 Triassic diabase 10 Environment of deposition 11 Structure 12 Folds 12 Faults 12 Border faults 12 Jonesboro fault 12 Western border fault 12 Cross faults 12 Longitudinal faults 13 The formation of the Deep River basin 13 The Coastal Plain 13 Stratigraphy :. .13 Upper Cretaceous Tuscaloosa formation 13 Lower member 14 Upper member : 15 Environment of deposition 16 Tertiary Pinehurst formation 18 Stratigraphy 18 Environment of deposition 19 Structure 19 Other Deposits . 20 Terrace gravel 20 Alluvium 20 Economic Geology 20 Pyrophyllite 20 Pyrophyllite mines and prospects 20 McConnell prospect 21 Jackson prospect 21 v Page Bates mine 21 Phillips and Womble mine 21 White mine : 21 Jones prospect 21 Currie prospect 21 Standard Mineral Company mine 21 Dry Creek mine 22 Ruff mine ' 22 Hallison prospect 22 Sanders prospect 22 Origin of pyrophyllite — : 22 Rock types 23 Faults . . 23 Outline of pyrophyllite bodies 23 Mineralogy 23 Zoning 23 Discussions and conclusions 24 Gold -24 Mode of occurrence 24 Gold mines 24 Clegg mine 24 Wright mine 24 Cagle mine 25 Red Hill mine : 25 Allen mine 25 Burns mine 25 Brown mine : 25 Shields mine 25 California mine _ 25 Dry Hollow placer mine 26 Jenkins mine : 26 Richardson mine 26 Monroe mine 26 Bell mine . 26 Ritter mine 26 Donaldson mine , 26 vi Page Copper 27 Coal i 27 Quality and reserves .1 27 Coal mines 27 Murchison mine _- 27 Garner mine 27 Black shale and black band 28 Stone 28 Sand and gravel 28 Pinehurst formation 28 Terrace gravel 28 Upper member of Tuscaloosa formation 28 Triassic gravel 28 High silica quartz : 29 Vein quartz : -29 Unconsolidated quartz sands and gravels 29 Clay . 29 Residual kaolin in the Carolina Slate Belt 29 McEnnis pit 29 William pit 30 McDuffy pit 30 Other clay in the Carolina Slate Belt 30 Pottery clay 30 Hancock pit 30 Cagle mine clay 30 Sedimentary clay in the Deep River basin 30 Sedimentary kaolin in upper member of the Tuscaloosa formation 31 Acknowledgements 31 References cited 38 vn Illustrations Plates Plate 1. Geologic Map of Moore County in pocket Plate 2. Geologic Map of Pyrophyllite Deposits, Glendon in pocket Plate 3. Geologic Map, Standard Mineral Company Pyrophyllite mine, Robbins in pocket Plate 4. White Pyrophyllite Mine, Glendon in pocket Plate 5. Geologic Map of Dry Creek Pyrophyllite mine in pocket Plate 6. Photomicrographs of Typical Volcanic Rocks page 32 Plate 7. Photographs of Typical Rock outcrops page 34 Plate 8. Photographs of Typical Rock outcrops page 36 vin GEOLOGY AND MINERAL RESOURCES OF MOORE COUNTY, NORTH CAROLINA By James F. Conley INTRODUCTION Location and Area Moore County is located in the south central part of North Carolina, between 35 degrees 04 minutes and 35 degrees 31 minutes north latitude and 79 degrees 12 minutes and 79 degrees 46 minutes west longitude. The county is irregular in outline with much of its boundary following streams and other natural features. It is bounded on the north by Randolph and Chatham counties ; on the east by Lee, Harnett, and Cumberland counties ; and on the west by Richmond and Montgomery counties. Scotland County lies immediately to the south, but has a common boundary at only one point. Moore County contains about 862 square miles and ranks 18th in size among the 100 counties of the State. Purpose and Scope A geologic mapping program was initiated in Moore County, North Carolina in the fall of 1959 by the North Carolina Division of Mineral Resources. The purpose of this research program was : (1) map the geology in as much detail as time permitted; (2) locate both the active and abandoned mines, study their economic possibilities, mode of origin and relationship to the regional structure; and (3) attempt to locate new mineral deposits which might be of economic value. Only the southern half of ,the county is covered by topographic maps. Therefore, a base map for the northern half was prepared from aerial photo-graphs at a scale of one inch equals one mile. The geology was plotted directly on contact prints and transferred to the base map. In the area underlain by rocks of the Carolina Slate Belt, outcrops vary from poor to non-existant and in several instances saprolite and soils had to be relied on to deduce the underlying rock type. Outcrops in the Coastal Plain are better exposed, except in a few instances where drainage is poorly developed. The northern part of the Triassic Deep River basin was mapped by John A. Rinemund (1955) during the period 1946-1949. Portions of his map are reproduced as part of the geologic map accompanying this report, with only minor changes. GEOGRAPHY Culture Moore County was established on July 4, 1784, from land which originally comprised part of west-ern Cumberland County. An additional tract bound-ed by James Creek, Little River, Hector Creek, and the Harnett County line was transferred from Hoke County in 1959. The county was named in honor of Alfred Moore, a military colonel in the American Revolution. Carthage, located near the center of the county, was established as county seat in 1803 and has served in that capacity since. Other principal towns include Aberdeen, Pinehurst, Robbins and Southern Pines. The county is served by three railroads. The Sea-board Air Line Railroad passes through the towns of Cameron, Vass, Southern Pines, Aberdeen and Pinebluff and is the main north-south route. The Norfolk Southern Railway has two east-west lines which serve the area. One crosses the northern part of the county passing through Glendon and Robbins, and the other, located in the southern part, passes through Aberdeen, Pinehurst and West End. From Aberdeen, southward, the area is served by the Rockfish and Aberdeen Railroad. A network of federal, state and county roads provide easy access to all parts of the county. In addition, regularly scheduled airlines operate out of Knollwood Airport, located a few miles north of Southern Pines. Moore County has a well balanced economy and a great variety of income-producing resources. Among the major of these are agriculture, mining, recrea-tion, and retail and wholesale trades. Climate Moore County is noted for its hot summers and mild winters, which make it a "mecca" for winter golfing and equestrian sports. The mean annual temperature is 61.1° F. The summer temperature averages 73.2° F; the winter temperature raverages L 50.2° F. The average precipitation is 44.61 inches, most of which occurs in the spring and early sum-mer (U. S. Weather Bureau, 1961). Physiography Moore County contains parts of two of the major physiographic provinces of the United States. The northern two-fifths of the county lies within the Piedmont Plateau province, locally referred to as the "clay country", whereas the southern three-fifths of the area is in the Sandhills subdivision of the Atlantic Coastal Plain province. In the area where the softer unconsolidated ma-terials of the Coastal Plain come in contact with the more resistant rocks of the Piedmont, there is a relatively narrow transition zone which in other places is marked by an abrupt change in relief. This contact is referred to as the Fall Line or Fall Zone. The Fall Zone occurs in Moore County as an uneven contact from near White Hill at the northeastern boundary westward through Carthage to a point on the western boundary about two miles north of Highway N. C. 211. In contrast to other areas, the Fall Zone in Moore County is a conspicuous topo-graphic ridge which forms a drainage divide be-tween northeast and southeast flowing streams. A third physiographic subdivision is the Triassic basin which lies in a northeast-southwest direction across the county. This depression or trough is about 10 miles wide and is tarecable from the north-east corner of the county southeastward to Harris, where it is covered by the sediments of the Coastal Plain. Even where covered by the Coastal Plain, the area underlain by Triassic sediments is lower than the surrounding countryside. The Triassic basin contains relatively soft sedimentary rocks which are much less resistant to erosion and have been removed at a more rapid rate than the crystal-line rocks of the uplands to the west. Topography Moore County is an area of contrasting topography. The uplands, underlain by crystalline rocks range in elevation from 600 feet above sea level in the north-western part of the county to only 300 feet in the northeastern part. Topography is typical of the Piedmont with rounded hills and V-shaped valleys. The hilltops rise from 75 to 100 feet above the valley floors, with a few rising as high as 150 feet. The Triassic basin ranges in elevation from 250 to 500 feet. The eastern and western rims of the Triassic basin lie as much as 250 feet above its floor and form prominent escarpments. From the escarpments the land slopes rapidly to the basin floor. Northeast trending ridges of low relief occur in the basin. These usually do not rise more than 75 feet above the valleys. Valleys in the Triassic basin are wider than in the uplands and some con-tain floodplain deposits. The average elevation of the Coastal Plain is about 400 feet; however, it ranges from 500 feet along its northern limits to less than 190 feet in river valleys at the extreme eastern tip of the county. The Coastal Plain is sculptured into alternating flat-topped ridges with convex sides that rise as much as 150 feet above broad, flat valleys filled with floodplain deposits. This topography is typical of the Sandhills region. Relief is considerably greater than found in the Coastal Plain outside of the Sand-hills. Drainage Moore County is drained by three major streams; Deep River, Little River, and Drowning Creek. Deep River enters the county along its north-central border and flows in a semicircle leaving the county at its northeastern corner. It drains almost all of the northern half of the area and has several major tributaries, including Bear Creek, Buffalo Creek, Falls Creek, McLendons Creek and Governors Creek. Little River heads up in central Moore County and flows eastward draining the central and east-central part of the area. Its main tributaries are Crane Creek, James Creek and Nicks Creek. The southwestern and southern boundary of the county is formed by Drowning Creek, which also drains this area. Its major tributaries are Jackson Creek, Horse Creek, and Aberdeen Creek. GEOLOGY The Carolina Slate Belt The northwestern part of Moore County is under-lain by low-grade metamorphic rocks of volcanic and sedimentary origin. The area in which these rocks crop out is known as the Carolina Slate Belt. The name Carolina Slate Belt was first applied by Nitze and Hanna in 1896. This name is a misnomer and should be replaced because the predominant rocks are not slates, and they do not form a belt. West of Moore County they are dominantly argil-lites, but in the county they are mostly phyllites with some slates. Although the outcrop area ap-pears as a belt, it is now known that these rocks extend under the Coastal Plain for a considerable distance. This is indicated by oil-test wells drilled in Bladen and Pender Counties, which bottomed in these rocks. In 1822 Olmstead described novaculite, slate, hornstone, and talc from areas now known to be underlain by the Carolina Slate Belt. In 1825 he referred to the "Great Slate Formation", which "passes quite across the state from northeast to southwest, covering more or less the counties of Person, Orange, Chatham, Randolph, Montgomery, Cabarrus, Anson and Mecklenburg". He described the rocks of this "formation" as consisting of clay slate or argillite porphyry, soapstone, serpentine, greenstone and whetstone. Eaton (1820) in a re-port on gold in North Carolina, added "talcose slates" to the list of rocks occurring in the belt. He stated that they occur in association with novacu-lite. Ebenezer Emmons (1856) probably one of the most competent geologists of his time, placed these rocks in his Taconic system which he divided into an upper and a lower member. He considered these rocks amongst the oldest in this county. The upper member consisted of clay slates, chloritic sandstones, cherty beds, flagstones, and brecciated conglom-erates. The lower member consisted of talcose slates, white and brown quartzites and (on his cross section, Plate 14, he added) conglomerate. Emmons, not recognizing volcanic rocks in his series, considered them water-laid sediments. The divisions of his system into an upper and a lower member is used, with modifications, in this report. Kerr (1875) described the rocks of the Carolina Slate Belt and proposed that they were of Huronian age. Williams (1894) first recognized volcanic rocks in the Carolina Slate Belt. Becker (1895) publish-ed a paper recognizing the presence of volcanic rocks in the sequence and proposed that they were Algoncian age. Nitze and Hanna (1896) recognized volcanic - rocks interbedded with the slates that they proposed were laid down during times of volcanic outbursts, followed by inactivity during which time slates were deposited. They noted that some of the rocks had true slaty cleavage, whereas others were truly schis-tose. They believed these rocks were altered by dynamo-and-hydro-metamorphism. Weed and Watson (1906) studied the Virgilina copper deposits and proposed that the country rocks were metamorphosed andesites. The age was thought to be Precambrian. Laney (1910) described the Gold Hill Mining District of North Carolina. In this report he divid-ed the rocks into slates with interbedded felsic and mafic flows and tuffs. He stated that the slates differ from the fine, dense tuffs only in the amount of land waste they contain, indicating that the slates, in part, were derived from volcanic material. He did not define "land waste", nor did he explain how it might be recognized. He stated that the rocks all show much silicification and are only locally sheared. He proposed that a major fault, the Gold Hill fault, separated the igneous rocks to the west from the slates. Pogue (1910) described the Cid Mining District, and Laney (1917) described the Virgilina Mining District. Interpretations in these reports are, in general, repetitions of ideas as expressed in Laney's report of 1910. Stuckey (1928) presented a report which included a geologic map of the Deep River Region of Moore County. He divided these rocks into slates, acid tuffs, rhyolites, volcanic breccias, and andesite flows and tuffs. He noted that the schistosity dipped to the northwest and interpreted the structure as close-ly compressed synclinorium with the axes of the folds parallel to the strike of the formations. He stated (p. 23) "The minor folds dip steeply to the northwest side of the troughs and flatten out to the east. The synclinal troughs pitch and flatten out in places as is indicated by the way the slate bands, which are all synclinal in structure, occur in long narrow lenses often pinching out. This pinching and flattening indicates some cross folding". He noted the slates seem to have consolidated readily and to have folded as normal sediments; whereas, the tuffs and breccias remained in a state of -open texture and tended to mash and shear instead of folding. He stated that there is little evidence for faulting, although minor displacements amounting to a few inches were noted. Stuckey, from a com-parison of his investigation with work by Laney and Pogue, concluded that the rocks of the whole slate belt are of the same general types. He noted that metamorphism is not uniform throughout the area. Theismeyer and Storm (1938) studied slates near Chapel Hill that showed fine-graded bedding, and proposed that they represented seasonal banding. Theismeyer (1939) proposed that similar sediments found in Faquier County, Virginia, were deposited in pro-glacial lakes during late Precambrian and early Cambrian times. The bedding is thought to be seasonal "varves". In addition he proposed that "the Hiwassee slates of Tennessee and the slates in North Carolina, near Chapel Hill, belong to the same category; even may have been deposited more or less contemporaneously". Stratigraphy The rocks of the Carolina Slate Belt have been divided, by Conley (1959) and Stromquist and Con-ley (1959) in the areas covered by the Albemarle and Denton 15-minute quadrangles, into a lower unit composed of volcanic rocks, a middle unit com-posed of volcanic and sedimentary rocks, and an upper unit of volcanic rocks which unconformably overlies the two lower units. In Moore County only the lower and middle units appear to be present; however, some rhyolites in the area might belong to the upper unit. The exact stratigraphic relation-ships of some of the rocks in the county are in doubt because of the gradational nature of the contacts, a condition further complicated by intense folding and faulting and lack of outcrops. Lower Volcanic Sequence Felsic Tuffs and Flows : Rocks of the Lower Vol-canic sequence are the oldest rocks exposed in the county. This unit on the order of 3500 feet thick, is composed predominately of fine, usually sheared, felsic crystal tuffs. The tuffs vary in color from white or light cream to light grey. They weather white and sometimes white weathering rinds are ob-served on fresh rock. Topsoil developed on these rocks is a cream-colored silty loam; the subsoil is a white clay loam. The rocks are usually massive. However, in a small area on Mill Creek west of West Philadelphia, they contain obscure bedding planes. In thin section the tuffs are composed of quartz, orthoclase, and plagioclase, probably albite in com-position, in a fine groundmass of what appears to be cryptocrystalline quartz accompanied by sericite and kaolinite. Feldspars appear as clouded, angular lath-shaped fragments partly replaced by sericite. The sheared appearance is much more apparent in thin section than in hand specimen. The quartz grains are crushed and drawn out in the direction of shearing. The groundmass has a banded appear-ance resulting from segregation of kaolinite and sericite along planes of shear. Interbedded with the felsic crystal tuffs are felsic lithic-crystal tuffs, rhyolites, and mafic crystal tuffs. The contact between the felsic crystal tuffs and the felsic lithic-crystal tuffs usually is gradational with well defined contacts being the exception. The lithic-crystal tuffs have the same matrix composition as the crystal tuffs, but in addition contain grey por-phyritic, rhyolite fragments which range from one eighth of an inch to more than six inches in diameter. These fragments range from well rounded to highly angular masses ; others appear to be flattened. The groundmass is now composed of cryptocrystalline quartz, sericite and kaolinite. The phenocrysts con-sist of quartz and lath-shaped orthoclase and pla-gioclase feldspars, the latter varying in composition from albite to oligoclase. Some of the tuffs are welded and exhibit flow lines. They could easily be mistaken for rhyolites if it were not for the pres-ence of lithic fragments. The flow lines usually are well defined in thin section due to the development of sericite along the flow structures. The rhyolites occur in small outcrops in the ex-treme northwestern corner of the county near West Philadelphia and on the hill above the Dry Creek pyrophyllite mine. Rhyolites are difficuilt to differ-entiate from flow tuffs, even in unmetamorphosed rocks, and these may be flow tuffs. They are classi-fied as rhyolites on the basis of swirl flow banding, euhedral feldspar phenocrysts, and the absence of either broken crystal of lithic fragments. The rhyolites are porphyritic, containing visible feldspars up to one-sixteenth of an inch in length. They are light grey in color, weathering to chalky white on the surface. They are exceedingly dense, emitting a metallic ring when struck with a hammer. This rock usually is not sheared even when tuffs on either side of some outcrops have suffered consid-erable shearing. They contain prominent swirl-banded flow lines which are accentuated by weather-ing. Because of their resistance to weathering the rhyolites form elongate hills. Soils developed on the rhyolite are extremely shallow, ranging from 12 to 15 inches in thickness. In thin section, the rhyolites are composed of ag-gregates of unoriented, interlocking, angular, quartz grains; untwinned orthoclase; and albite and carls-bad twinned oligoclase. The groundmass is exceed-ingly fine and can not be resolved to individual crys-tals, but appears to be an interlocking network of cryptocrystalline quartz, sericite and kaolinite. Mafic Tuffs: The mafic tuffs shown on the geo-logic map (Plate 1) are not limited to any one rock sequence, but are found interbedded with the felsic tuffs, and andesitic tuffs of the Lower Volcanic sequence as well as slates of the overlying Volcanic- Sedimentary sequence. However, mafic tuffs are more frequently associated with the andesitic tuffs. Evidently, outburst of mafic ejecta occurred over a considerable span of geologic time. Because of the lithologic similarity of the mafic tuffs they are all shown, for convenience, as the same color on the map. These rocks in general are andesitic in composi-tion, but contain some material that might be classi-fied as basalt. They are composed of lithic frag-ments ranging from one-sixteenth of an inch up to eighteen inches in diameter, and crystal fragments, ranging from microscopic up to one fourth of an inch in diameter. From place to place, the ratio of crystals to lithic fragments is exceedingly variable, as is the size of the elastics making up the rock. The tuffs usually are sheared. They have a grey-ish- green or olive-green color when fresh, becoming dun-brown on weathering from the oxidation of their iron. Topsoils developed on these rocks are tan-colored silty loams; the subsoils are usually dark-brown to chocolate-brown colored heavy clay loams. In thin section the matrix of the rock appears to be made up almost entirely of chlorite bands strung out parallel to shearing. Feldspars have been alter-ed to sericite and kaolinite. In highly sheared rocks, phenocrysts have, been rolled parallel to schis-tosity and have an augen-like appearance. One thin section contained quartz masses that appear to be crushed, unoriented, and strung out parallel to schistosity. These quartz masses might be second-ary fillings of vessicles. The lithic fragments appear to be of different composition than the matrix of the rock. Some specimens are composed of a mesh of lath-shaped feldspar crystals about 0.02 of a millimeter in length with chlorite filling the interstices. Augite, not al-tered to chlorite, is present in rare isolated frag-ments. The groundmass of some of the fragments is composed of sericite and kaolinite rather than chlorite. In general, the rock is not bedded. However, in the area north of High Falls the mafic tuffs contain numerous interbeds of graywacke. These interbeds range from a few tens of feet to more than over a hundred feet in thickness. The graywacke is green-ish- grey when fresh, becoming light-brown on weathering. It is composed of quartz, feldspar, rock fragments, and a small quantity of argillaceous ma-terial. The rock exhibits graded bedding consisting of coarse sand, rock fragments up to two centimeters across, and intermixed fine sand at the base, which grades upward into fine sand at the top of the bed. The rock fragments, so prominent in hand specimen, are reduced in thin section to aggregate of kaolinite, chlorite and sericite. This suggests that the frag-ments are completely altered and are only recogniz-able in hand specimen by the preservation of relic structures. Andesite Tuffs : The andesite tuffs are about 2500 feet thick and are composed of interbedded crystal tuffs, lithic-crystal tuffs, argillaceous lithic conglom-erates, argillaceous beds and questionable flows. These tuffs are highly susceptible to shearing and usually exhibit axial plane cleavage. Many of them are sheared and pass into phyllites in which primary fragments are flattened and elongated in the direc-tion of movement. The andesite tuffs have a dis-tinctive greyish-purple color when fresh, and on weathering become a lighter purple. This coloring is due to primary hematite in the rock. Topsoil de-veloped on the andesite tuffs is a dark, red-clay loam and the subsoil is a dark-maroon to maroonish-pur-ple colored heavy plastic clay. , Crystal fragments in the more tuffaceous phases rarely exceed 40 percent of the composition of the rock. They consist almost entirely of lath-shaped feldspar fragments and rare euhedral crystals, rang-ing in length from microscopic to three millimeters. The feldspars are highly sericitized and are both carlsbad and albite twinned. Gross composition is ap-proximately that of andesine. In addition to feld-spar, lath-shaped masses of chlorite are also present. This chlorite probably represents altered amphibole and pyroxene. Quartz is rare in the crystal tuffs; however, one questionable flow tuff consisted of 30 percent of almost spherical quartz grains ranging up to two millimeters across. This is probably sec-ondary quartz filling vessicles. The interstices are filled with hematite which obliterates the ground-mass. Lithic-crystal tuffs are readily differentiated from argillaceous lithic conglomerate. The fragments are angular and the matrix contains crystal frag-ments in the lithic tuffs ; whereas, the fragments are rounded and the matrix is argillaceous in the lithic conglomerates. The rock fragments in both the tuffs and conglomerates are similar in composition. They rarely exceed two inches in diameter in the conglom-erates, but range up to ten inches across in the tuffs. Megoscopically these fragments are of two types. One is a massive aphanite, and the other is a crystal flow rock. Microscopically the aphanite fragments consist almost entirely of sericite and hematite; the flow-rock fragments appear as an aggregate of unoriented feldspar laths averaging about 0.02 of a millimeter in length in a matrix of hematite. Aside from flow lines and crystals, the original composi-tion and texture of the flow rock fragments are masked by hematite. The groundmass of the tuffs is so fine grained that it can not be resolved under the microscope. It appears to be composed predominately of elongate masses of opaque hematite, sericite, chlorite, and kaolinite. Epidote occurs sparingly in some thin sections. The matrix of the argillaceous rocks is even finer grained and also is obscured by hematite. Near the top of the stratigraphic section the ande-site tuffs become more argillaceous and bedding is observed more frequently. As the contact with the overlying slates is approached, graded bedding, so common in the slates, begins to predominate. Volcanic-Sedimentary Sequence Slates : The slates are about 6,000 feet thick and form the basal unit of the Volcanic-Sedimentary se-quence? They attain the greatest elevation of any stratigraphic unit found in Moore County? There is no sharp contact between this rock and the under-lying andesitic tuffs, but there is a gradational strati-graphic change from tuff to slate. Fine graded bed-ding, resembling varved bedding, is a characteristic of the slates. The bedding planes vary from one-sixteenth to one-fourth of an inch in thickness. Axial plane cleavage usually is more pronounced than bed-ding. The fresh slate is dark grey in color and weathers to ocherous reds and yellows. Topsoils are usually light brown-colored silts; whereas, subsoils are light red silty loams. In thin section graded bedding is easily observed. It consists of a silt layer at the bottom which grades upward into clay layer. The silt sized particles pre-dominately consist of quartz grains as well as some feldspar and what were probably ferromagnesian minerals, now chloritized. The clay layers are now predominately sericite. The slates outcropping in the eastern part of the county, along the western contact with the Triassic basin, contain interbeds of graywacke sandstone, which in places make up as much as fifty percent of the rock. These graywackes have a different composition and texture than those interbedded with the mafic tuffs. They are greyish-green when fresh and weather light maroon. They usually appear to be massively bedded; however, closer inspection reveals thin bedding planes and graded bedding ranging in size from sand at the bot-tom to silt at the top. The rock is composed of equal parts of chloritized rock fragments and quartz with occasional grains of albite-twinned sericitized feld-spar which ranges in composition from oligoclase to andesine. The rock varies in composition from the base to the top of the graded beds. The matrix fill-ing the interstices between the sandgrains in the lower parts of the beds consist of about equal parts sericite and kaolinite with a trace of chlorite. As the beds become finer grained toward the top, chlo-rite increases until the upper silt fraction of the bedding is composed of approximately sixty percent chlorite, fifteen percent sericite, fifteen percent kao-linite and ten percent quartz. Environment of Deposition The Lower Volcanic sequence is thought to be vol-canic ejecta deposited on land. This is indicated by 6 the general angularity of lithic and crystal frag-ments and the general lack of sorting in the sedi-ments. Pillow structures, which only form in subaqueous flows, are not present in the interbedded rhyolites, even though flow lines are well preserved. If pillow structures had developed, they should be as well pre-served as the flow lines. The presence of welded flow tuffs also suggest subaerial deposition because it is unlikely these rocks could have retained enough heat to flow and weld if they were deposited in water. The tuffs on Mill Creek contain bedding and might be water laid. However, air laid tuffs often contain bedding and are deposited in water. The presence of graywacke interbeds in the mafic tuffs suggest an aqueous en-vironment and turbidity currents. These gray-wackes were probably, for the most part, derived from reworking of the mafic tuffs. The coarse mafic-lithic breccias and mafic crystal tuffs, so commonly interbedded with the andesitic tuffs, were evidently blown out of volcanoes and deposited directly in water without reworking. The numerous rounded lithic fragments, bedding planes, and fissle graded bedding suggest that the andesite tuffs were water laid. The presence of inter-bedded lithic-crystal tuffs and argillaceous lithic conglomerates of essentially the same chemical composition suggests that these rocks were derived from the same source. One probably represents vol-canic ejecta deposited directly in water without re-working, and the other a reworked sediment. The gradual increase in graded bedding toward the contact with the overlying slates suggest a change in environment from shallow to deep water. The andesite tuffs are thought to represent a transi-tion unit and a transition environment between the terrestial tuffs and flows of the Lower Volcanic sequence and the deep-water sediments of the over-lying Volcanic-Sedimentary sequence. The slates were deposited in quiet water, below wave base. This is indicated by the fine graded bedding which could only develop in quiet waters. The mechanism which produces fine graded bed-ding is not thoroughly understood. Theismeyer (1939) proposed that the slates were varved sedi-ments deposited in pro-glacial lakes during late Pre-cambrian or early Cambrian times. No glacial de-posits have been identified in the rocks of the Caro-lina Slate Belt and this theory is not acceptable. It has been suggested that varve-like graded bed-ding can only occur in water of low salinity because of flocculation. This is indicated by Fraser's (1929) experimental studies which showed the maximum salinity permitting the formation of varves of coarse clay to be about one fiftieth that of sea water. Petti-john (1949) stated that graded bedding occurs in sediments from Precambrian to the present and sug-gested that flocculation by sea water is a doubtful concept. Kuenen and Menard (1952) believed that graded bedding in graywackes is caused by turbidity currents and can occur in normal sea water. Two methods are proposed which might produce graded bedding in the slates. One postulates that the sediments were derived from silt and clay sized ash blown out of volcanoes. The larger sized par-ticles would immediately settle out of the air allow-ing them to be deposited in the water first. The smaller sized particles Would be thrown higher in the air and, buffeted by air current and take longer to settle out. This would produce a graded sediment due to air sorting before the material reached the water. The second method postulates that the grad-ed bedding was produced by turbidity currents. During rainstorms, streams would become charged with sediments. Upon reaching the basin of depo-sition, the water charged with sediments would be more dense than water in the basin; and would move slowly down the sub-aqueous slope as a weak turbidity current. As this current moved outward it would deposit a silt layer. As it lost its turbidity and velocity, the clay sized particles would gradually settle out on top of the silt layer. The presence of graywacke sandstones containing graded bedding adds strength to the turbidity current theory, be-cause graywackes are now usually regarded as' tur-bidity current deposits (Pettijohn 1957). Structure Folds Troy Anticlinorium : The major structure in Moore County is the Troy Anticlinorium, which trends in a northeast-southwest direction and plunges toward the southwest. This structure has been traced from southern Montgomery County to northern Randolph County. The anticlinorium is over 30 miles wide, lying between the Pee Dee River on the west and western Moore County in the east. The axis of the fold is located near Troy, Montgom-ery County, and the southeastern limb occupies northwestern Moore County. The felsic tuffs of the Lower Volcanic sequence crop out in the center of the structure, whereas the overlying andesite tuffs and slates dip off its southeastern flank. Minor Folds : A series of usually double-plunging anticlines and synclines, varying in wavelengths from one to three miles are developed on the south-east flank of the Troy anticlinorium. These folds are overturned to the southeast and cleavage developed parellel to the axes of the folds dips monotonously to the northwest at angles varying from fifty-five to seventy degrees. Schistosity and shearing increased from northwest to southeast across the county. In the northwestern part of the county the Lower Vol-canic sequence dips under the overlying rocks but reappears in the center of anticlinal folds across the central and southwestern part of the county. The slates, the youngest Carolina Slate Belt stratigraphic unit found in Moore County, occupy the center of a number of overturned synclines in the central and eastern part of the area. The slates are contorted into a series of undulating open folds varying in wavelength from ten to thirty feet across. These folds probably developed due to plastic flowage within the slates during regional folding. Faults Faults can be divided into two groups; namely, northeast trending longitudinal faults developed parallel to the axes of folds, and northwest trending cross faults. Because of slippage parallel to the axes of overturned folds, many of the longitudinal faults are reverse in nature. The zones of displace-ment along the major northeast trending faults usually have been intruded by quartz veins and are occasionally silicified and mineralized. The quartz veins and silicified zones are invariably sheared, indicating movement occurred along these faults after intrusion of the quartz veins and silicifica-tion. The cross faults have displaced the longitudinal faults in a number of places, clearly indicating that they developed after the longitudinal faults. Major movement along the cross faults was strike slip-page. Along the Deep River in the northern part of the county these cross faults can be traced into the Triassic basin. The cross faults have displaced the Carolina Slate Belt units as much as a mile along the strike, but have displaced Triassic rocks only a few hundred feet. This indicates the major movement took place in pre-Triassic time with a later movement of much smaller scale taking place after deposition of the Triassic sediments. Longitudinal Faults Glendon Fault: One of the major longitudinal faults in the area is the Glendon fault. It lies ap-proximately three miles northwest of Glendon and can be traced from the northern county line south-eastward to just north of Robbins. It strikes north 60 degrees and dips 60 to 70 degrees northwest. Drag folds indicate that it is a reverse fault, with movement from northwest to southeast. It is offset by several cross faults along its length. A wide mineralized shear zone containing workable pyro-phyllite deposits accompanies the fault. Movement along the fault has placed the andesite tuffs in con-tact with the slates, except north of McConnell, where it has placed felsic tuffs underlying the ande-site tuffs in contact with the slates. This suggests that the throw in this area must be in the order of several thousand feet. Robbins fault: The Robbins fault passes through the western city limits of Robbins and is traceable from approximately one mile north of Robbins, southeastward to approximately one mile northeast of West Philadelphia. It trends north 60 degrees east and dips northwest at approximately fifty de-grees. Drag folds indicate that it too is reverse in nature and the hanging wall to the northwest moved upward over the footwall to the southeast. The shear zone accompanying this fault is as much as a mile wide and contains pyrophyllite and gold de-posits. The reverse nature of this fault and pres-ence of pyrophyllite deposits along its trace sug-gests that it is the same type as the Glendon fault. In fact, if the strike of the Glendon fault were ex-tended to the southwest (see Plate 1), it would in-tersect the Robbins fault south of Robbins. Other Longitudinal faults : A horst structure, ly-ing between two north sixty-five degrees east trend-ing vertical faults, occurs in the area between Put-nam and Hallison. This structure places felsic tuffs of the Lower Volcanic sequence in contact with slates of the Volcanic-Sedimentary sequence. The andesite tuffs lying stratigraphically between the felsic tuffs and the slates are omitted, indicating a throw in the order of several thousand feet. This horst is adjoined on the northwest by a graben which lies between the fault north of Putnam and the Glendon fault. Cross faults : Vertically dipping northwest trend-ing normal cross faults, which strike from thirty to seventy degrees northwest, occur throughout the central and eastern part of the county. Some of these appear to be hinge faults; whereas others show strike slippage. A number of strike-slip faults along Deep River have a horizontal displacement varying from half a mile to over a mile. The Deep River has entrenched along these faults producing a series of parallel meanders. Southeast of Spies a pair of northwest-trending faults have produced a graben structure, downfault-ing andesite tuffs against felsic tuffs. A number of transverse faults have been intruded by diabase dikes. The dikes evidently were emplaced along zones of weakness; however, it is not under-stood why they preferred northwest trending faults and generally ignored those trending northeast. DEEP RIVER TRIASSIC BASIN The Deep River Triassic basin lies in a northeast-southwest direction across Moore County. In the northern part of the county it is bounded on either side by the Carolina Slate Belt. In the southern part of the county it. is overlapped by Coastal Plain sediments. Emmons (1852) on the basis of fossil and litho-logic evidence, concluded that the sediments of the Deep River basin were Triassic age. However, in 1856 he proposed that the lower sandstones and coal beds were of Permian age, because of the presence of Thecodant saurian teeth in some of the shales associated with the coal beds. Overlying sandstones were still considered Triassic age. Redfield (1856) found that the rocks in New Jer-sey, Eastern Pennsylvania and in the Connecticut Valley were Upper Triassic age and proposed that they be named the Newark group. He found that fossil vertebrates in Emmons collection were identi-cal to those occurring in the northern basins and cor-related sediments in the Deep River basin with the Newark group. Rocks of the Deep River basin consist of red, maroon, reddish-grey fanglomerates, conglomerates, sandstones and siltstones. In addition the basin contains coal beds and associated grey and black shales, mudstones, siltstones and sandstones. Emmons (1852) subdivided the stratigraphy of the Deep River Basin into three units. These are : 3. Sandstones, soft and hard with freestones, grindstone grits, and superior conglomerates ; crop-ping out along the eastern edge of the basin. 2. Coal beds and black slates with their subordi-nate beds and seams ; cropping out in- the center of the basin. 1. Inferior conglomerates and sandstones below the coal beds and black slates; cropping out along the western edge of the basin. This was a logical conclusion because the strata dip toward the eastern edge of the basin. Although he devised this classification, Emmons (1856) recog-nized marked resemblance between certain strata on the eastern and western part of the basin and suggested that they might be the same unit. In 1856 he repeated this classification in his text; however, on the map accompanying the report, in-serted an additional unit which he called "Salines" between the middle and upper units. Campbell and Kimball (1923) stated that the "Salines" are nothing more than drab shales, containing salt, above the coal beds, and belong with the middle division. Campbell and Kimball (1923) mapped and named Emmons' three units calling the lowest the Pekin formation, the middle the Cumnock formation and the upper the Sanford formation. Prouty (1931) discussed the formation of the Deep River basin. He proposed that it was caused by downwarping aided by development of an eastern border fault. Reinemund (1955) published a detailed study of the structure and stratigraphy of the Deep River basin with special emphasis on the economic geol-ogy. Stratigraphy Pekin Formation: Campbell and Kimball (1923) named the basal Triassic unit, the Pekin formation after a small town in southern Montgomery County. No type section or type locality was established, but they stated that it is best exposed on the road trend-ing due east from Mt. Gilead. The formation under-lies the western third of the Deep River basin in Moore County and is exposed along the western bor-der of the basin from Deep River southward to the Coastal Plain overlap. The formation is estimated to be from 1750 to 1800 feet thick. Its basal part is supposed to rest on the eroded- surface of the Caro-lina Slate Belt, (Reinemund 1955). To the south, along Drowning Creek, the western border of the basin is flanked by a lithic fanglomerate composed of angular to subrounded rock fragments, derived from the Carolina Slate Belt, ranging from one inch to over a foot in diameter. An elongate conglomerate bed, lenticular in out-line, resembling a shoestring sand lies along the western border of the northern part of the basin. This bed was extensively quarried before 1900 to make millstones, and is known locally as the Mill-stone Grit. The bed varies in thickness from 2 to 30 feet, and is composed of quartz pebbles, varying from one to three inches in diameter, in a matrix of coarse sand. The conglomerate is well cemented and the pebbles can be broken without being dislodged from the matrix. A paleosoil underlies the Millstone Grit in an out-crop on Highway N. C. 22 at the old Parkwood quar-ry. It is a grey, carbonaceous, partly-kaolinized clay containing numerous root impressions. East of the western border, the Pekin formation is composed of lenticular beds of red, brownish-red, and maroonish-purple clayey siltstones, sand-stones and occasional beds of brown or grey, medium to coarse grained, cross bedded, arkosic sandstones and conglomerates. Rare thin beds of claystone are also present. Many of the sandstones contain root impressions on weathered surfaces. Toward the center of the basin the sediments be-come finer grained, with siltstones predominating. To the southeast the sediments become progressively coarser, and frequently contain more arkosic beds as well as coarse-grained, grey-colored, cross-bedded sandstones. Cumnock Formation: Campbell and Kimball (1923) named the middle coal-bearing Triassic beds the Cumnock formation after the Cumnock mine. The type section was located in the main shaft of the mine. The Cumnock formation is exposed in northern Moore County from Deep River southward to the Coastal Plain overlap. On the road between Glendon and Carthage it-is repeated four times by faulting. In the north-central part of the basin the Cum-nock formation is 750 to 800 feet thick and consists of coal, black and grey shales, with thin sandstone beds in the middle and upper part (Reinemund 1955). The Pekin-Cumnock contact was placed by Emmons at the top of the last redbed below the coal beds, and the Cumnock-Sanford contact at the first redbed above the coal. The two workable coal beds occur about 200 feet above the base of the Cumnock formation. The lower coal bed, called the Gulf seam, has been found only at the Carolina and Black Diamond mines and lies from 25 to 45 feet below the second, or Cumnock bed (Reinemund 1955) . The Cumnock formation and associated coal beds is the thickest near the center of the basin, thinning rapidly toward the edges. The formation is best developed at Carbonton and Gulf and apparently thins rapidly to the southwest. This is indicated by the Cumnock coal bed which is reported to be 42 inches thick at Cumnock, but only 14 inches thick at an exposure at the Gardner mine. Campbell and Kimball (1923) noted the area, two miles wide, northwest of Carthage in which the Cumnock formation does not crop out. They postulated that this might be caused by either lateral gradation of the grey Cumnock strata into the red beds of the Pekin and Sanford formations, or down faulting, but seemed to favor faulting as the explanation. The Cumnock formation dips under the Coastal Plain sediments four miles southwest of Carthage, and has not been observed in outcrop south of the point. An exception to this might be the grey silt-stone and mudstone exposed in a stream valley one and one-half miles southwest of Eagle Springs, on the road to Samarcand Manor. Whether or not this is actually the Cumnock formation or a variation of the Pekin formation is open to question, because this exposure lies considerably north of a projection of the last Cumnock outcrop. It is thought that the reason the Cumnock formation does not crop out south of Carthage is because it is downfaulted along the continuation of the Governors Creek fault. The Cumnock formation reappears further to the south-west as indicated by a coal prospect located in Mont-gomery County near the Moore County line. Sanford Formation: The Sanford formation was named by Campbell and Kimbell (1923) after the town of Sanford and included all rocks above the Cumnock formation. The Sanford formation con-formably overlies the Cumnock formation, and in Moore County this contact might best be described as gradational. The Sanford formation is estimated to be from 3500 to 4000 feet thick (Reinemund 1955) and covers the eastern half of the Deep River basin. Reinemund (1955) stated that the Sanford formation contained few distinctive beds which can be traced over any appreciable distance. The beds are lenticular and laterally gradational. Measured sections would only apply to rocks in the immediate vicinity and correlation is not feasible over wide areas. The Sanford formation similar to the Pekin formation, is predominately a sequence of redbeds. It also is composed of sandstones, siltstones, con-glomerate and fanglomerate. To the southwest, the formation becomes progressively coarser and con-tains more frequently occurring beds of coarse arkosic sandstone. Fanglomerate crops out, in a belt varying in width from three-fourths to over a mile wide, along the southeastern edge of the basin. It is composed of unsorted rock fragments ranging from one-half an inch to more than a foot in diameter. These frag-ments were derived from rocks of the Carolina Slate Belt and usually are poorly indurated. Material filling the interstices between the fragments usually is composed of red and maroon sandstones and silt-stones. The fanglomerate shows very poor bedding ; however, the general dip of the rock can be ascer-tained by observing the orientation of tabular rock fragments. From the eastern border and toward the center of the basin, the fanglomerat grades lat-erally into conglomerate. In addition to the fan-glomerate, the Sanford formation contains well-defined lenticular beds of quartz conglomerate which are sometimes cross-bedded. These lenses usually grade into sandstones. Beyond the border of the basin the majority of the Sanford formation consists of interbedded red and maroon siltstones and sandstones. Claystones and shales are almost totally absent. The coarser sandstones are most prevalent along the eastern edge of the basin with siltstones becoming predominant toward the center of the basin. These sandstones are similar to the sandstones of the Pekin forma-tion, along the northwestern edge of the basin and contain numerous root impressions. Unnamed Upper Conglomerate: Northeast of Carthage a grey conglomerate lies on the eroded sur-face of the Sanford formation (see Plate 1). Prob-ably the best exposure is in a new road cut on a hill rising above the east bank of the east fork of Big Governor's Creek. The conglomerate consists of well rounded quartz pebbles, ranging in size from one-half to two inches in diameter, intermixed with a minor amount of coarse angular sand. In addi-tion it contains minor lenses of siltstone. The rock is poorly consolidated and usually is not stained with the red iron oxides as generally is the case with Triassic rocks. The Triassic age of the conglom-erate is well established because it has been intruded by a diabase dike. After observing this conglomerate, J. L. Stuckey informed the author that similar gravels occur near Apex, North Carolina. The Apex locality was visit-ed by Reinemund and Stuckey in 1948, at which time they reached the conclusion that the gravels were of Triassic age and appeared to be younger than the Sanford formation. It might be argued that these gravels are part of the Sanford formation because unconformable beds within the formation are relatively common. This possibility certainly cannot be ruled out. However, a better explanation is that these gravels probably are post Sanford floodplain deposits as indicated by the preservation of old stream channels. Triassic Diabase : Diabase dikes generally regard-ed to have been emplaced in late Triassic time, have intruded both the Deep River Triassic basin and the Carolina Slate Belt. In the Deep River basin a num-ber of dikes have intruded the Sanford formation northwest of White Hill. Dikes and large sills have intruded the Cumnock formation northeast and southeast of Glendon. Dikes occasionally occur in the Pekin formation west of Carthage. Diabase dikes have been mapped in the Carolina Slate Belt and are most numerous in the area between High Falls and Parkwood. 10 The diabase dikes in general trend northwest, with a few exceptions trending either north or northeast. These dikes dip either vertically or slightly to the northeast. They range in thickness from one to several tens of feet. Diabase dikes oc-curring in the Carolina Slate Belt are usually smaller than those in Triassic sediments. This leads to the conclusion that the magma could more easily intrude and incorporate the less resistant Triassic sedi-ments. The existence of low refractory shales and coal in the Cumnock formation might explain why large sills occur in this unit. Even where they in-trude Triassic sediments, the baked zones on either side of the diabases are rarely over twice the thick-ness of the dikes, and- in the Carolina Slate Belt these zones do not exceed a few inches. The baked zones usually are dark grey at the contact with dia-base, becoming reddish grey away from the contact. The diabases are exceedingly susceptible to spher-oidal weathering producing rusty boulders scattered through the surficial soil. Soil, developed on weath-ered diabase is a conspicuous dark-yellow brown, but occasionally is a dark-chocolate brown. During the field investigation for this report little attention was given to the petrography of the dia-base dikes. Reinemund (1955) studied the diabases in detail. He found that they contain the primary minerals olivine, plagioclase feldspars, varying from andesine to bytownite, augite, orthoclase and quartz ; the accessory minerals magnetite, ilmenite, pyrite, chromite, titanite, apatite, and basaltic hornblend; and secondary minerals antigorite, limonite, horn-blende, calcite, and magnetite. Olivine is usually present in varying amounts. The rock usually con-tains as much as two-thirds plagioclase and as much as one-third augite. In addition to normal diabase, gabbroic varieties composed of one-half olivine and one-third plagioclase and dioritic diabase composed of one-half plagioclase and one-third augite are present. Envioronment of Deposition Kryniene (1950) expressed the opinion that red color of the Triassic sediments was due to erosion of red soils in the source area. Reinemund (1955) essentially agreed with this, and added that the dark brown and red colors of the Pekin and Sanford formations indicated that the sediments were de-posited in a non-reducing environment. During the time of deposition of both the Pekin and Sanford formations fluvial conditions existed in the Deep River basin. At this time both the border faults had well defined scraps. Talus material ac-cumulated at the base of these scarps producing the fanglomerates found in the Pekin formation along the western edge of the basin and the Sanford formation along its eastern edge. From the edges toward the center of the basin, sediments of both formations become progressively finer grained. Reinemund (1955) stated that sedi-ments of the Pekin and Sanford formations were deposited by streams, as indicated by the cross bed-ding and the channel like form of some of the coarse grained sediments. Root impressions, commonly found in the sandstones of these formations, sug-gest that much of the area between the major stress channels was marshland. General coarsening of the grain size of the sediments to the southwest indicate that drainage within the basin was in that direction. Gradual sinking of the basin probably occurred during sedimentation by slight movements along the border faults, causing rejuvination from time to time of streams flowing into the basin. During the latter part of Pekin sedimentation the scarp of the Western border fault in the northern part of the county did not stand at elevations great enough to produce talus deposits. At this time, a stream, in-cised along the fault scarp, deposited the Millstone Grit. The occurrence of the Cumnock formation, with its black shale and coal beds in the center of the basin, represents a change from stream and shallow marshes, with rapid sedimentation along the mar-gins of the basin ; to a shallow lake, with slow sedi-mentation in the center of the basin. A shallow body of standing water could support a lush growth of vegetation. After death the organic remains would fall to the bottom of the lake and be protected from oxidization. Extremely slow sedimentation would allow accumulation of organic material of thickness and purity to form workable coal beds. After the basin had filled with sediments, streams meandered over its surface depositing the unnamed, upper gravels which overly the Sanford formation. It is suggested that deposition of parts of the Pekin, Cumnock and Sanford formations, as map-ped, might have occurred simultaneously. Only in areas of outcropping Cumnock formation can the names Pekin and Sanford formations be used as time-stratigraphic units. In these areas redbeds underlying and in direct contact with the Cumnock formation can definitely be called the Pekin forma-tion, and inversely, the redbeds overlying the Cum-nock formation belong to the Sanford formation. Because grey shales and coal beds of the Cumnock formation are limited to the center of the basin, redbeds deposited along the eastern and western margins of the basin during Cumnock time are most 11 likely mapped as Sanford and Pekin formations re-spectively. As no key horizons exist along the mar-gins of the basin, it would be best to regard what has been mapped in these areas as Pekin and San-ford formations as sedimentary facies rather than time-stratigraphic units. Structure Folds: The Deep River basin has been described by Campbell and Kimball (1923) and by Reinemund (1955) as a synclinal basin. In this paper the basin is considered a graben structure in which the beds dip monoclinally to the south-east. The syncline which Reinemund (1955) regarded as the axis of the basin occurs northeast of White Hill. Another small syncline lies along the west bank of McLen-don's Creek, where Highway N. C. 27 crosses the creek. Approximately eight tenths of a mile north of this area is located the axis of a small anticline. Folds of large magnitude have not been observed within the Deep River basin in Moore County. Faults: Reinemund (1955) found three ages of faults in the Deep River basin. The oldest is the Jonesboro fault or eastern border fault, which re-mained active during sedimentation ; the cross faults are next in age, developing after sedimentation had ceased ; and the longitudinal faults are the youngest. This is indicated by the fact that the cross faults have displaced the Jonesboro fault, but not the longi-tudinal faults. In turn, the longitudinal faults have offset the cross faults, but are not offset by the cross faults. Border Faults Jonesboro Fault : The Jonesboro fault was named by Campbell and Kimball (1925) after the town of Jonesboro. It forms the eastern contact of the basin placing Triassic sediments against the Carolina Slate Belt. Reinemund (1955) estimated that the maximum vertical displacement along this fault is on the order of 6000 to 8000 feet. The fault strikes north 35 degrees east in the northeastern part of the county, but changes to a more easterly direction south of Eastwood, where it assumes a strike of about north 60 degrees east. The fault plane dips to the northwest at an angle of about 65 degrees. Reinemund (1955) observed that the Jonesboro fault is displaced by cross faults, although no displace-ment along the fault was noted in Moore County. Western Border Fault : The Western Border fault forms the western contact of the basin and also places Triassic sediments against the Carolina Slate Belt. Campbell and Kimball (1923) did not recog-nize the Western Border fault, and Reinemund (1955, Plate 1) has only mapped a few discontinu-ous faults along the western border of the basin. Authors of both these papers suggested the sedi-ments wedge out to the northwest. They proposed the sediments were once more extensive in that direction, but have been eroded away. This concept might be true of other areas of the Deep River Basin but could not be applied in Moore County. If the Triassic sediments wedged out to the west, it would be expected that streams would have eroded through the Triassic mantle exposing rocks underly-ing the basin, producing a scalloped contact. The contact is not scalloped, it is an essentially straight line, suggesting a fault contact. In addition, the fanglomerate, exposed along the western border of the basin in the southern part of the county, indi-cates that the fault scarp in this area was once a significant topographic feature. Campbell and Kimball (1923) and Reinemund (1955) considered the Millstone Grit a basal con-glomerate. The buried soil under the Millstone Grit indicates that it is not a basal conglomerate and that Triassic sediments had been deposited and weathered before the conglomerate was laid down. The presence of this fault is further indicated by a gravity survey of the Deep River-Wadesboro Basin conducted by Mann and Zablocki (1961). They stated that in places the basin has graben like fea-tures, but suggest that throw of the Western Border fault in the Deep River basin is less than that of the Jonesboro fault. The Western Border fault is best exposed at the bridge across Deep River, north of Glendon, on the Glendon-Carthage road. It strikes north 30 degrees east and dips to the southeast at 60 degrees. North of Eagle Springs the fault is bent to a more westerly direction and strikes north 55 degrees east. The vertical displacement is unknown but it is thought to be in the same order of magnitude as that of the Jonesboro fault during time of sedimentation. How-ever, post depositional movement along the Jones-boro fault exceeded that of the Western border fault which remained stable, causing the strata to dip to the southeast. The Western Border fault has been displaced in numerous places by cross faults through-out its exposed area. Cross Faults : Northwest trending cross faults are found throughout the Deep River basin. As pre-viously mentioned, along the Western border some of these faults begin in the Carolina Slate Belt and end in Triassic sediments. The major displacement has been parallel to the strike. Vertical displace-ment is usually minor being on the order of a few 12 tens of feet and occasionally ranging over one-hun-dred feet. Reinemund (1955) noted the faults ex-tend to great depth because many of them have been intruded by diabase dikes. In Moore County the cross faults trend about north forty degrees west; however, in rare instances, they trend from north twenty degrees west to almost due north. The fault planes are usually at high angles approaching verti-cal and generally dip to the northeast. Longitudinal Faults : A series of northeast trend-ing step faults, including the Deep River, Governors Creek, and Crawleys Creek faults, lie in a northeast direction across the center of the Deep River basin. These faults have repeatedly exposed the Cumnock formation in the northeastern part of the county. The fault planes dip to the northwest at angles varying from 20 degrees to thirty degrees. The ver-tical displacement varies from five-hundred to over two-thousand feet. Displacement gradually becomes less to the southeast and all of the faults except the Governors Creek fault die out before they have an opportunity to dip under Coastal Plain sediments. It is thought that the Governors Creek fault con- - tinues across the southern part of the basin, and is a rotational fault with its hinge line near Carthage. The Western block moved down northeast of the hinge line, but up southwest of the hinge line. This explains why, along this fault line, the Pekin forma-tion is in direct contact with the Sanford formation in the southern part of the county and the Cumnock formation in the northern part of the county. The Formation of the Deep River Basin Campbell and Kimball (1923) concluded that the Deep River basin was caused by downwarping of the earth's crust. Sediments were deposited in this trough causing it to continue to sink. After down-warping and sedimentation ceased, the basin was faulted. Prouty (1931) agreed that the basin was caused by downwarping, but believed the Jonesboro fault developed soon after sedimentation began. He pos-tulated that movement along this fault continued sporadically until sedimentation ceased. This pro-duced a wedge shaped trough, with the thickest sedi-ments next to the fault, becoming progressively thinner away from the fault. The last movement along the Jonesboro fault, as well as the development of faults in the basin occurred after deposition. The present investigation indicates the Deep River basin in Moore County is a rift valley caused by downfaulting along the Jonesboro and Western Border faults. These faults are thought to have existed in Pre-Triassic time and were reactivated in Triassic time producing the basin. The sequence of event which produced the Deep River basin in Moore County are as follows : 1. Removement along the Pre-Triassic Jonesboro and Western Border faults, during Newark time, creating a graben trough. 2. Disruption of drainage and beginning of sedi-mentation. 3. Continued movement along the border faults and possible fractional movement along the cross faults with continued sedimentation. 4. Stabilization of the faults with cessation of sedimentation. 5. Removement along the Jonesboro fault, drop-ping down the eastern side of the basin and tilting the strata to the southeast, accompanied by active movement along cross faults. 6. Development of longitudinal tension faults in the center of the basin. 7. Intrusion of the diabase dikes, predominately along northwest trending cross faults in both the Carolina Slate Belt and Deep River Triassic basin. THE COASTAL PLAIN Stratigraphy Upper Cretaceous Tuscaloosa Formation: The Tuscaloosa formation is the basal Coastal Plain unit in Moore County. In this report it is divided into a lower and an upper member. The Tuscaloosa forma-tion was named by Smith and Johnson in 1887 after the city of Tuscaloosa, Alabama. L. W. Stephenson (1907) subdivided the Cretaceous of North Caro-lina into three formations. He called the basal unit the Cape Fear formation. He considered it Lower Cretaceous in age and correlated it with the Patux-ent formation of Virginia. He named the overlying unit the Bladen formation, (Black Creek formation in present terminology) and correlated it with the Tuscaloosa formation of Alabama. In 1912 he re-named the Cape Fear formation the Patuxent forma-tion and correlated it, on lithology, with the Patux-ent of Virginia and Maryland. Sloan (1904) named the sands and clays of sup-posedly Lower-Cretaceous age in South Carolina, the Middendorf Formation. However, Berry (1914) studied plant fossils from this formation and found that they were actually of Upper Cretaceous age. Cooke (1936) correlated the Middendorf formations 13 of South Carolina with the Tuscaloosa formation of Alabama and extended the Tuscaloosa into North Carolina. Horace G. Richards (1950) described the Tuscaloosa formation in North Carolina and stated that it occurred in southern Moore County. W. B. Spangler (1950) from a study of cuttings obtained from oil-test wells drilled on the North Carolina Coast, found that the subsurface contained both lower and upper Cretaceous beds. He applied the name Tuscaloosa formation only to beds of Eagle Ford-Woodbine age. P. M. Brown (1958) also found rocks of Woodbine and Eagle Ford age in the subsurface stratigraphy of the North Carolina Coastal Plain. These he assigned to the Tuscaloosa (?) formation. S. D. Heron (1958) mapped the basal Cretaceous outcrops between the Cape Fear River in North Carolina and the Lynches River in South Carolina. He returned to the Classifications of Stephenson and Sloan, dividing the Tuscaloosa formation into the Lower Cretaceous ( ?) Cape Fear formation and the Upper Cretaceous Middendorf Formation. He nam-ed the lower part of the Black Creek formation, be-low the Snow Hill member, the Bladen member. Heron (1960) stated, "The Middendorf is considered the updip facies of the Bladen member of the Black Creek formation and both of these formations have overlapped the Cape Fear formation." Groot, Penny and Groot (1961) collected samples containing plant microfossils from the Tuscaloosa formation of the Atlantic Coastal Plain, including one sample from the basal part of the lower member of the Tuscaloosa formation in Moore County. They found that the Tuscaloosa formation of the Atlantic Coastal Plain is Upper Cretaceous age, but slightly older than Senonian, although some Senon-ian species are present. Lower Member: The lower member of the Tus-caloosa formation is the basal unit of the Coastal Plain sediments in Moore County. It rests uncon-formably on both the Carolina Slate Belt and the Triassic Deep River basin. This member is best exposed in the southeastern part of the county, where overlying younger sediments have been strip-ped away by erosion. It is rarely exposed in the south-central and southwestern parts of the county, where it usually is covered by overlying sediments. The base of the lower member is exposed in a road cut on the west side of Highway U.S. 15-501 on the south side of Little River. At this locality it is underlain by the Triassic Sanford formation. The basal part of the member is a grey carbonaceous clay containing lignitized wood. The section at this exposure is as follows : Section near juunction of Highway 15-501 and Little Rixer Top of section covered Cretaceous (Tuscaloosa formation member) Thickness 6. Weathered reddish brown clay.— 3' 5. Dark grey plastic carbonaceous clay 3' 4. Fine greyish green sand : 1' 3. Dark grey plastic carbonaceous clay, containing liginitized wood 4' 2. Basal gravel _ '. 6' Unconformity Triassic (Sanford formation) 1. Fanglomerate 3' Base of exposure The gray carbonaceous clay of the basal part of the lower member is again exposed in the west bank of a paved road on the south side of Nicks Creek, approximately one mile north of Murdocksville. This locality contains both wood fragments and amber. The type locality of the lower member of the Tus-caloosa formation is an exposure along the Seaboard Air Line Railroad in the center of the town of Vass. The section at this locality is as follows : Section at Vass Recent Thickness 7. Soil zone, weathered and leached, being colored sand with occasional gravel beds 6' Cretaceous (Tuscaloosa formation lower member) 6. Oxidized, mottled light olive and red clay 4' 5. Oxidized, iron cemented, greyish-olive sandstone 1' 4. Oxidized, light olive silty clay 8' 3. Oxidized, feldspathic, micaceous clayey course olive sand, with occasional gravel beds stained by hematite 6' 2. Oxidized, micaceous olive clay, containing some silt and sand 3' 1. Unoxidized, micaceous, light grass green sandy clay.. 6' Base of exposure A water well, located approximately one-fourth of a mile northwest of the type locality, drilled for the town of Vass by C. C. Hildebrand and Company, record the following section : Log of Water Well at Vass Thickness 8. White and yellow sand 4' 7. Yellow sand clay 16' 6. Light yellow and light grey sand clay.. 5' 5. Light grey sandy clay - 10' 4. Light brown sandy clay 10' 3. Water bearing sand - 35' 2. Light brown sand clay 15' 1. Basement rocks of the Carolina Slate Belt 364' An exposure southeast of Lobelia on the south bank of Little River at Morrison, Bridge, Hoke County, is as follows : 14 Section along Little River at Morrison Bridge Cretaceous (Tuscaloosa formation, lower member) 2. Festooned cross-bedded micaceous, feldspathic, grey-ish white and light grey, poorly consolidated sand, containing lignitized logs, grey clay balls, and heavy mineral streaks. (These streaks are composed of as much as 50 percent pyrope garnet. The lignitized logs are partly replaced by plastic grey clay in which growth rings are preserved) 5' 1. Unoxidized light grass green, micaceous, sandy clay 1' River level Two exposures of well cemented coarse sandstone occur in the county. One is located northwest of Taylor Town on the north bank of Joes Fork Creek, and the other on the north shore of a private lake, just above Hog Island intersection. Judging from the elevation of the exposure, neither of these out-crops could be far above the base of the unit. The two sandstones are identical in appearance and, if they could be correlated, might be of stratigraphic significance. These sections are as follows : Section along Joes Fork Oreek northwest of Taylor Town Cretacious (Tuscaloosa formation, lower member) Thickness 3. Oxidized reddish brown clay 3' 2. Coarse grained, well cemented greyish brown sandstone 2' 1. Oxidized light grey clay. 2' Base of exposure Section: at Hog Island Cretaceous (Tuscaloosa formation, upper member) Thickness 5. Basal quartz gravel 2' Unconformity (Tuscaloosa formation, lower member) 4. Dark grey clay mottled with secondary hematite____ 1.5' 3. Dark grey clay 3.5' 2. Coarse to medium grained, well cemented greyish brown sandstone 2' 1. Dark grey silty clay ...„ 3' Base of section A complete stratigraphic section of the lower mem-ber of the Tuscaloosa formation in Moore County is not available, but from what is known, it can be stated that the basal part consists of grey carbonace-ous clays containing lignitized plant remains and amber, with interbedded thin, grey and olive sand beds. Above the base, the clays become less carbon-aceous and lighter grey in color ; finally giving way to light olive clayey sand beds containing thin clay beds. Some of the sands exhibit faint graded bed-ding and cross bedding. Although a few of the clay beds are lenticular in outline, most persist over the exposed outcrop area. In the subsurface some beds can be correlated on electric logs traced over wide areas (P. M. Brown, personal communication). Upper- Member: The upper member of the Tusca-loosa formation unconformably overlaps the lower member as well as segments of the Carolina Slate Belt and Deep River basin. The outer limits of the upper member is an irregular contact which can be traced in a northeast-southwest direction across the county. Typical exposures are found in the area around Harris Crossroads; however, measure sec-tions in this unit are of questionable value because of the extreme variable nature of the sediments. For this reason, a type section of the upper member of the Tuscaloosa formation has not been established. The base of the upper member is exposed at a number of localities along the margin of the Coastal Plain. It is an unconsolidated gravel composed of rounded quartz, varying from one to six inches in diameter. These gravels were probably derived from quartz veins in the Carolina Slate Belt. This basal gravel is thin, usually not over six feet thick, and in some places is totally absent. The basal gravels become finer grained and diminish in thick-ness to the southeast and might completely disappear down dip. The gravels have a bleached appearance, and might have been subjected to intensive weather-ing, which removed iron staining, before transporta-tion. Though some of the cobbles show faint pink staining, the absence of iron contrasts with both vein quartz in the Carolina Slate Belt and Recent terrace deposits. The matrix of the basal gravel is composed of kaolinitic clay and clayey sand. Small quantities of heavy minerals are interspersed through the matrix. Above the basal gravel, the upper member of the Tuscaloosa formation consists of alternating uncon-solidated beds of white clay and clayey sand. The clay beds pinch and swell and sometimes die out. These beds are composed of white plastic kaolinite, which, if weathered, is often stained pink by iron oxide. Quartz grains up to one millimeter in diam-eter are randomly scattered throughout the clays, and sometimes make up as much as five percent of the deposit. These quartz grains are usually very angular, almost glass clear, and show little or no rounding and frosting. In addition to the quartz, the clays also contain mica shards. The sand beds usually are more persistent than the clay beds, although they also tend to thicken, thin and occasionally pinch out. Most of the sand beds are relatively massive and are only faintly bedded. Some are crossbedded and others exhibit graded bed-ding. A few of these deposits contain occasional fine gravel interbeds. Kaolinitic clay galls, varying from one-half to one and one-half inches in diameter, occur sparingly in the gravel beds and along promi- 15 nent bedding planes. The sands are composed of medium to coarse, sub-rounded quartz grains with mica shards, feldspar grains, and rare heavy min-eral streaks along bedding planes. The sands are bonded together by kaolinitic clay. This clay, which is always present, at times makes up as much as twenty-five percent of the sediment. Thin beds of hematite up to one inch thick occur as a precipitate from groundwater on the upper sur-faces of many of the clay beds and along prominent bedding planes in the sand beds. Hematite and occasionally limonite precipitates, have oftentimes cemented the base of the upper mem-ber of the Tuscaloosa formation. These deposits are as much as six inches thick. Environment of Deposition : The lower member of the Tuscaloosa formation was probably deposited in a marine environment. Although marine fossils are lacking in Moore County, they have been recover-ed from well cuttings down dip (P. M. Brown, per-sonal communication). The persistence of the beds and general rarity of cross bedding suggest these sediments were laid down under marine conditions. The gradual change from grey carbonaceous clays at the base to green and olive clayey sands and thin grass green clay beds above the base, probably rep-resents a change from lagoonal, with stagnant con-ditions, to marine environment, brought about by transgression of the Lower Tuscaloosa sea. Other evidence for the marine origin of the lower member of the Tuscaloosa formation is suggested by Heron's (1960) study of exposed basal Cretaceous clays of North and South Carolina. He found that known marine sediments contain abundant montmo-rillinite, whereas sediments regarded as non-marine contain kaolinite. He found that the Cape Fear formation (lower member, Tuscaloosa formation) contained predominately montmorillinite with some kaolinite, suggesting that it is a marine sediment. The samples collected from the lower member of the Tuscaloosa formation of Moore County were X-ray analyzed by Heron at the request of the author. These were found to contain a majority of montmorillinite over kaolinite (S. D. Heron, writ-ten communications). Although montmorillinite as an indicator of marine origin is still open to question by some authors ; the present investigation suggests that it is applicable in this case. The environment of deposition for the upper mem-ber of the Tuscaloosa formation has been discussed in the literature. L. W. Stephenson (1923) believed the Patuxent formation to be of alluvial origin, deposited by overloaded streams crossing the Coastal Plain of that period, which existed between the coast line to the east and the highlands to the west. Veatch (1908) stated that the almost pure kaolin-ite beds in the Tuscaloosa formation were clearly of sedimentary origin. He postulated that these sedi-ments were derived from deeply-weathered crystal-line rocks of the Piedmont in which the feldspar and other aluminus minerals had altered to kaolinite. During Cretaceous time, these weathered rocks were rapidly eroded and deposited along the sea as alluvial fans and at the mouths of streams as deltas. On these deltas fresh water lakes were formed and filled with reworked kaolinite clay. As these lakes were filled, others formed. Newman (1927) agreed that the clays were de-rived from weathered rocks of the Piedmont, but postulated that they were leached to essentially pure kaolin in situ in pre-Cambrian time, under the in-fluence of mild climate with heavy rainfall, aided by acid conditions created by decaying vegetation. This weathered material was then eroded, transported by streams, and deposited in a marine environment. Kesler (1957) agreed with Veatch's deltaic origin, but added that the sediments were derived from a youthful erosion surface. He postulated that the kaolins were formed by weathering of feldspars after deposition of the sediments, and were concen-trated by later reworking. Heron (1960) stated "The sediments of the Mid-dendorf formation (upper member Tuscaloosa formation) probably represent an environment that was dominately fluvial". He suggested that the rela-tively pure clay bodies, having the shape of small basins, may represent deposition in a floodplain, such as the filling of an abandoned meander. The upper member of the Tuscaloosa formation in Moore County is considered unfossiliferous although is contains marine fossils down dip (P. M. Brown, personal communication) . This fact has led to the development of various theories about its environ-ment of deposition of which too little attention has been paid the source of the sedimentary kaolin beds in the updip facies of the upper member. In regard to this fact, a residual clay is developed on Carolina Slate belt rocks directly underlying the upper member. It is felt that this residual clay is indicative of the source of the sedimentary clay in the upper member of the Tuscaloosa formation. If the crystalline rocks of the southeast were blanketed prior to Upper Tuscaloosa time, by residual kaolins, which were eroded and deposited during Upper Tus-caloosa time, this would explain the widespread oc-currence of sedimentary kaolins in the upper mem-ber of the Tuscaloosa formation. 16 Norlh Carolina State Library Raleigh The McKennis pit (see Plate 1, for location) is a typical residual kaolin deposit. The stratigraphic section exposed in this pit is as follows : Section of McKennis Clay Pit Recent Thickness 5. Present day soil zone which extends down from the surface into unweathered gravel 4' Tertiary (Pinehurst formation) 4. Gravel ._: 1' Unconformity Cretaceous (Tuscaloosa formation, upper member) 3. Pink and white mottled clayey sand 3' 2. Basal gravel _._ 1' 1. Kaolinitic clay containing quartz veins, still pre-serving the fine alternating graded bedding of the slates. (The relic bedding strikes north 45 degrees east and dips southeast at 30 degrees) 2' Base of section This locality was visited by Mr. E. F. Goldston, North Carolina State College, Department of Soils, at the request of the author. At the time of exami-nation, Mr. Goldston stated the following about the deposit : 1. The Coastal Plain is too thick for the kaolin to have been formed in place by weathering after depo-sition of the Upper Tuscaloosa member and overly-ing sediments. 2. A climate capable of producing this degree of weathering and leaching would, of necessity, have been warmer and had more rainfall than present. A section exposed on the north bank of Little River, where the Murdocksville road crosses the river, is as follows : Section of Little River Thickness Cretaceous (Tuscaloosa formation, upper member) 4. Sandy clay 8' 3. Basal gravel composed of quartz pebbles, ranging in diameter from 1 to 6 inches, in a mtarix of kaolinitic sand 2' 6" Triassic (Sanford formation) . 2. Sandy kaolinitic clay, developed on the Sanford formation grading downward into unweathered red sandstone 3' 6" 1. Red sandstone 2' Base of section This section indicates that Triassic rocks as well as the Carolina Slate Belt were highly weathered and leached prior to deposition of the upper member of the Tuscaloosa formation. Occurrences of residual kaolin underlying the Tus-caloosa formation in Georgia suggest that the pre- Upper Tuscaloosa mantle was an extensive deposit because Munyan (1938) states, "Recently the writer, while mapping Cretaceous rocks (in Georgia) saw a number of contacts between the Tuscaloosa and the underlying crystalline rocks. The crystalline rocks were weathered to primary kaolin in many instances and could be identified as crystallines only by the presence of thin, but continuous quartz veins. The overlying rock could easily be identified as unaltered sediment. In no case observed did it appear that the weathering of the underlying crystalline rocks was due to leaching after the deposition of the sediment". From this evidence it is postulated that in pre- Upper Tuscaloosa time the Carolina Slate Belt and the Deep River Triassic basin were peneplained and subjected to intensive weathering and leaching un-der tropical conditions, producing a thick residual kaolinitic mantel. In order to prevent the mantel from being eroded away as fast as formed, the area was, of necessity, relatively flat. If a transgressing sea slowly inundated this peneplaned surface, it would be expected that the upper member of the Tuscaloosa formation would have been laid down in a shallow environmental basin under near shore con-ditions. Streams emptying into this basin during flood stage, would bring in sediments ranging in sizes from clay to gravel. As the flood subsided the sediments would become finer grained, explaining why some of the sediments contained graded bed-ding. Cross bedding would be expected in such an environment. During times when the streams were not in flood stage, they would be carrying colloidal clay, which on entering the basin would slowly settle out as a thick viscous mass. The surface of the basin floor was probably irregular with more clay accumulating in the depressions than elsewhere. This explains why the clay beds pinch and swell. The next flood would bring in another slurry of coarse sediments which would be deposited on top of the clay beds. The colloidal clays would then act as highly viscous media allowing some of the sand grains from the overlying sediments to settle into the clay, while supporting the remainder. This ex-plains the presence of sand grains in otherwise pure kaolinitic clay. The coarse basal gravel of the upper member of the Tuscaloosa formation was probably derived from quartz veins which intruded the Carolina Slate Belt. The quartz could have been brought in by streams, however, it has been noted, in many places in Moore County, underlain by rocks of the Carolina Slate Belt, that the surface of the ground is covered by a lag pavement of vein quartz. If areas covered by these lag gravels were exposed to wave action of an advancing sea, this action could rapidly produce 17 a deposit similar to the basal conglomerate of the Upper Tuscaloosa member. As previously noted, the basal gravel is thin, variable in thickness, and in places totally absent. Pettijohn (1957, p. 244) states "blanket conglomerates . . . were deposits of gravel spread out by an advancing or transgressive beach. These deposits are notably thin and patchey; low areas may collect several tens of feet of gravel whereas the intervening high areas may be devoid of any gravel accumulation". the upper member of the Tuscaloosa formation. This contact is an undulating line, indicating a rough erosional surface developed on the upper member of the Tuscaloosa formation before deposition of the Pinehurst formation. This contact can be recog-nized at numerous localities in the county ; one of the better of these is exposed in the west bank of high-way U.S. 15-501 at the Vass road overpass, approxi-mately one and one-half miles southeast of Carthage. This section is as follows : TERTIARY PINEHURST FORMATION m Gravel beds overly the upper member of the Tus-caloosa formation in Moore County. The gravel deposits near Lakeview were described by Stephen-son (1912) and correlated with the Lafayette forma-tion of Pliocene age. Bryson (1930) described a number of gravel pits in Moore County and stated that the exposures are of one group and probably belong to the Lafayette formation. In the Halifax area, Mundorf (1946) recognized graven deposits which he called unclassified high level gravel. He postulated they were probably of differing ages ranging from Cretaceous to Tertiary. Richards (1950) recognized high level gravels in Moore County, but did not attempt to define the distribu-tion or suggest the age. Reinemund (1955) mapped high level gravels in Moore County and stated that they covered almost a fifth of the area shown in his geologic map. He considered all of the Coastal Plain deposits high level gravel, not recognizing the upper member of the Tuscaloosa formation which directly underlies the gravel throughout the county. The gravels are unfossiliferous and the exact age is not known. In the northeastern part of the State, similar deposits unconformably overlie the late Mio-cene Yorktown formation (P. M. Brown, personal communication). Although regarded as Pliocene age by Stephens et. al. it is conceivable that these surficial gravels could be Late Miocene, Pliocene, or Early Pleistocene age. Stratigraphy: During this investigation it was found that the so-called high-level gravels could be recognized and mapped as a stratigraphic unit in areas covered by Coastal Plain sediments. It is therefore proposed that this unit be called the Pine-hurst formation after the town of Pinehurst which is underlain by these sediments. The type section for the formation is located in the D. H. Wilson sand pit on the north side of Highway 211, approximately one and one-half miles southeast of the center of the town of West End. The Pinehurst formation unconformably overlies Section along Highway 15-501 at Vass Overpass Tertiary (?) (Pinehurst formation) Thickness 2. Brown limonite stained, faintly bedded, coarse sand; containing lenses of well rounded quartz gravel, ranging in size from one-half to two inches with interspersed kaolinitic clay balls 10' Unconformity Cretaceous (Tuscaloosa formation, upper member) 1. White kaolinitic clay, pink mottled at the top 2' In Moore County the Pinehurst formation is a nonfossiliferous sand and gravel which caps all of the higher Coastal Plain hills in central and western Moore County. It has not been observed resting directly on sediments older than the Upper Tusca-loosa. The Pinehurst formation is exposed on top of the high hill at Carthage, at an elevation of over 500 feet. From this elevation it slopes to the southeast, at first steeply, becoming more gentle down dip until it reaches an elevation of about 350 feet in the southern part of the county. The gravels on the hill at Carthage range in thick-ness from 3 to 7 feet and consist of a coarse-brown, iron-stained sand containing lenses of quartz peb-bles, ranging in diameter from 2 to 5 inches. Down dip the formation gradually thickens until, in the southern part of the county, it is over 150 feet thick. Bedding and composition rapidly change from coarse sands, containing pebble beds and lenses, at Car-thage to festooned cross-bedded sands and fine grav-els down dip. The formation usually is brown or greyish brown in color. It is often iron stained, and sometimes cemented with either hematite or limonite, hematite being the more common. Hematite concretions occur within the formation. The outside of these struc-tures are coated with sand grains. Although they are usually oval or spherical in outline, some have a stair step appearance from preservation of relic bending planes. When broken they are oftentimes hollow and contain hematite powder which local folklore attributes as the source of red Indian war paint. Sometimes this hematite occurs in lumps 18 and when a concentration is shaken emits a sound, from the hematite hitting the walls of the structure ; thus giving rise to the common name "rattle rock". Hematite and occasionally limonite is precipitated at the base of the formation in deposits varying from a few inches to over a foot in thickness. Kaolinitic clay balls are commonly interspersed throughout the formation. They usually occur along prominent bedding planes and in gravel beds. Heavy minerals are much more common in this formation than in the underlying Tuscaloosa, which is relatively devoid of heavy minerals. They are concentrated along bedding planes and are rarely dispersed through the sediment. The upper surface of these deposits is covered by olive-brown silt and fine sand ranging in thickness from one to five feet. These deposits are attributed to wind action in the form of winnowing. The process was probably aided in the recent past by denudation of the area by forest fires, but is still going on today as can be attested to by observing sparsely vegetated areas on a windy day. The Pleasant sand pits, between Pinehurst and Aberdeen, contain sediments dissimilar to the other parts of the Pinehurst formation. These deposits consist of water laid, well-sorted, thin-bedded, fine white sands; thin, fissle-bedded, grey silts and plastic clays ; and occasional micro-cross bedded fine sands. These deposits are covered by approximate-ly four feet of wind blown silt and fine sand. Because of the thinness of the Pinehurst forma-tion, the major streams have cut the deposit leaving it capping hills along stream divides and draping down the hillsides. These sand and gravel capped hills are commonly referred to as the "Sand Hills Region". Many times the tops of the hills are con-cordant, flat, and slope gradually to the southeast. These might represent preservation of original con-structional topography. Environment of Deposition: Lithology and ab-sence of fossils suggest the Pinehurst formation is nonmarine. However, it could have, in part, been deposited in a transition zone. In such a zone con-ditions for preservation of fossils are poor; and, if preserved, they could have been subsequently leach-ed away. The sediments were derived from a nearby source and carried by vigorous streams in a youthful stage of development, as indicated by the beds and lenses of coarse gravels in the coarse sands around Car-thage. A change of environment from stream to deltaic is indicated by comparing these deposits with the cross bedded, finer grained sands and gravels down dip. This change is further suggested by the gradient of the formation which is steepest at Car-thage, becoming rapidly less steep, almost flat, down dip. The beds of coarse gravel at Carthage and change in gradient down dip also indicates that one of the major streams emptying into the basin of deposition was located in the general vicinity of Carthage. As sedimentation progressed, deltas grew outward from the mouths of streams emptying into the basin, explaining why the formation thickens down dip. An interesting feature of the Pinehurst formation is the presence of kaolinitic clay galls. Although clay galls were occasionally observed in Upper Tus-caloosa outcrops, they are universally present in the Pinehurst formation. Whether the kaolinite was derived from erosional outliers of the underlying Tuscaloosa formation or from weathered Carolina Slate Belt rocks is open to debate. PettiJohn (1949) attributes the formation of clay galls to the dessica-tion and breaking up of mud cracks. Mud cracks could have easily formed on mud flats along deltaic distributaries and been incorporated in the sedi-ments when these mud flats were inundated during flooding. The final product of sedimentation was a series of coalescing deltas, creating a blanket deposit of cross bedded unconsolidated sand and gravel. The fine sands and clays exposed in the Pleasant sand pits were probably deposited in a small fresh water lake, created by blocking of one of the distributaries. Post depositional wind action in the form of win-nowing produced the fine sands and silts which cover the Pinehurst formation in many places. Structure: The Coastal Plain sediments dip to the southeast at six to eight feet per mile. This angle of dip is somewhat steeper than the average for the Coastal Plain, but these are deposits along the ancient coastal margines and should dip more steeply. No faulting has been observed in Coastal Plain sediments even though slicken-sides were ob-served in Upper Tuscaloosa clays in a borrow pit on the west side of Highway U.S. 1, at the southern city limits of Aberdeen. Erosional unconformities occur at the base of the lower member of the Tuscaloosa formation and at the base of the Pinehurst formation. The existence of an unconformity at the base of the upper member of the Tuscaloosa formation is suggested by the pres-ence of what appears to be a weathered zone develop-ed on top of the underlying lower member. A basal conglomerate in the upper member also suggests a break in the sedimentation cycle. 19 I Other Deposits Terrace Gravels: Although Reinemund (1955) mapped four levels of terrace gravels, this author only recognized and mapped three levels in Moore County. The lowest of the terraces (Terrace No. 1, Plate I) is found as scattered remnants along Aber-deen Creek, Little River, and Crane Creek. Sedi-ments underlying this terrace level consists of iso-lated patches of sand and gravel at elevations from ten to fifteen feet higher than present floodplains. It is light tan-colored coarse sand and well rounded gravel. The gravel fraction is composed predomi-nately of quartz with some Carolina Slate Belt frag-ments. The gravel is somewhat variable in size, ranging in diameter from 1 to 3 inches. The most extensive of the terrace deposits (Ter-race No. 2, Plate I) occurs from 20 to 30 feet above present floodplains. It is the only terrace level which has developed to any extent on the crystalline rocks of the Carolina Slate Belt. This level occurs along Cabin Creek, north of Robbins, and along the length of Deep River. The terrace deposits consist of yellow-brown fine sands and clayey sand with occasional interbedded silts and fine gravel. The gravels are one-quarter to one-half of an inch in diameter with some ranging upward to over one inch. These deposits are usually covered by 12 to 18 inches of coarse silt and fine sand. The highest of the stream terraces (Terrace No. 3, Plate I) , occurs at elevations of 65 to 70 feet above present floodplains. It is only found along Deep River east of Glendon and Little River north of Mt. Pleasant. Terrace deposits underlying this level are composed almost entirely of gravel with sand and clay filling the interstices. Rare thin interbeds of silty clay are present in the deposit. The subangular to rounded gravels are composed of approximately 70 per cent quartz and 30 percent Carolina Slate Belt rocks. The sand fraction is composed mainly of coarse, angular, quartz grains with occasional feldspar grains. Soils developed on these deposits have a distinc-tive red color. The "B" soil horizon is a maroonish-red sand loam, whereas, the "A" horizon is a red-dish- brown silty loam. The three levels of river terraces indicate three periods of downcutting and stream aggradation, followed by deposition of alluvial sediments in the valleys. Therefore, the highest of these deposits is the oldest ; the lowest is the youngest with each suc-cessive period of cutting lowering the stream and bringing it closer to the present base level. The periods of aggradation were probably caused by a drop in a sealevel ; the subsequent deposition by ris-ing sealevel. The river terrace deposits in North Carolina have been regarded in the literature as Pleistocene age. Successive sets of terraces were supposedly formed due to alternating glaciation and melting producing a rise and fall in sealevel. The terraces in Moore County do not contain fossils and have not been traced into known Pleistocene deposits; therefore, their age determination is left to conjecture. Alluvium: The alluvium filling present stream valleys consists predominately of chocolate-brown and greyish-brown silt with some light and lark grey organic clays. It is conspicuously absent in those parts of the county underlain by the Carolina Slate Belt. However, it is usually present along streams flowing over much of the Triassic basin and Coastal Plain. The presence or absence of alluvium is determined by the relative resistance to erosion or the rocks underlying the streams. ECONOMIC GEOLOGY Pyrophyllite Pyrophyllite is a hydrous alminum silicate classi-fied as a high alumina mineral. Its formula is Al2 3 .4 Si0o.Ho and consists of 66.7 percent Si02 , 28.3 percent A12 3 and 5.6 percent H20. It is used in the manufacture of ceramics, paint, rubber, insecticides, roofing, and paper. Its major produc-tion goes into ceramic products and mineral filler. Moore County contains the largest pyrophyllite ore reserves in the United States. This mineral has been mined near Glendon for over a hundred years. The pyrophyllite at Glendon was originally thought to be talc, until Emmons (1856) reported that it contained aluminum. He called it agalman-tolite, a soft material consisting chiefly of pyro-phyllite used in the Orient for making carvings. In addition he described the quarry at Hancock's Mill (Glendon) at some length. Brush (1862) analyz-ed material from Hancock's Mill and concluded that it was pyrophyllite. Pratt (1900) discussed the occurrence of pyrophyllite at Glendon and described Phillips, Womble, Rogers Creek, and other deposits. He noted that the pyrophyllite was often silicified and occurred in iron breccia which merges into pyro-phyllite schist. Stuckey (1928) investigated the pyrophyllite deposits of Moore County and discussed their location, size, mode of occurrence, origin, and economic possibilities. Pyrophyllite Mines and Prospects Pyrophyllite deposits occur in four areas in Moore County ; namely, north of Glendon, southeast of Hal- 20 lison, southwest of Robbins, and on Cabin Creek near the Montgomery-Moore county line. Eight pyrophyllite mines and prospects are located on the Glendon fault from McConnell northeast to the county line. This area contains the largest number of deposits in the county. Two pyrophyllite mines are located on the Robbins fault, south of Robbins. Both of these deposits are at present being mined. McConnell Prospect : The McConnell prospect lies approximately 0.5 of a mile northeast of the village of McConnell. The pits are now grown over, but the dumps contain sericite schist and foliated pyrophyl-lite. Highly sheared sericitized felsic tuff, in part silicified, is exposed along an access road, west of the prospect. Exposures available at the time of investigation indicate the shear zone of the Glendon fault in this area is only about forty feet wide and the mineralized zone approximately ten feet wide. Jackson Prospect: The Jackson prospect lies on the south side of Deep River approximately three miles northeast of the McConnell prospect. The shear zone of the Glendon fault in this area is about 200 feet wide. The deposit is located on the fault contact between andesitic tuff to the northwest and slates to the southeast. Two prospect pits have been put down to a depth of about 8 feet. They expose white foliated sericite ; however, no pyrophyllite was observed. Bates Mine: The Bates mine is located on the northeast bank of Deep River approximately two miles northeast of the Jackson prospect. Stuckey (1928) stated that this mine was prospected in 1903 and a mill constructed in 1904. The mine was op-erated until 1919 at which time it closed due to lack of quality ore. The rock is sheared and mineralized in a zone 150 feet wide, along the Glendon fault. The hanging wall to the northwest is composed of andesite tuff; the footwall to the southeast is composed of slate. The pyrophyllite is developed in a band, about three feet wide in the area of major displacement of the fault zone and grades into sericite schist on either side. The ore zone strikes north 70 degrees east and dips northwest at 80 degrees. Phillips and Womble Mines: The Phillips and Womble mines are separated from each other by the Siler City-Glendon road, and lie approximately two miles northwest of Glendon. These mines were map-ped by plane table and alidade at a scale of one inch equals 50 feet (see Plate 2) during the field investi-gation for this report. The Glendon fault is exposed for approximately 1800 feet along strike in active and abandoned mine workings. The ore body lies in the shear zone of the fault and dips to the northwest at an average angle of 65 degrees. The ore body is lenticular in outline and pinches and swells, but is considerably less in the pinches. Pyrophyllite has also been developed along minor displacements parallel to the main fault. White Mine : The White Mine is located on Rogers Creek approximately 0.8 of a mile northeast of the Womble mine. The ore body is contained between the Glendon fault on the southeast and a secondary reverse fault on the northwest. The ore body is lenticular in outline and dips to the northwest at an angle of 60 degrees. It is exposed along strike in the pit for 375 feet. Recent investigation indicates that the ore body continues to the southwest for a considerable distance. To the northeast it is not traceable beyond the mine. An exposure along the southwest wall of the pit reveals relatively unaltered rock overthrusting the ore body. The direction of movement along this fault was toward the southeast, indicating that the ore body might be overthrust to the northeast. The country rock surrounding the deposit is interbedded slate and andesitic lithic tuff and is stratigraphically in the gradational contact zone between the andesitic tuff and slate units. The contact between mineralized rock and unaltered rock is unusually sharp being gradational for only a few inches or at the most a few feet. Jones Prospect : The Jones prospect lies approxi-mately one and four tenths miles northeast of the White mine. Surface exposures indicate that the rock in this area is highly sheared. Prospect pits reveal foliated pyrophyllite and masses of sericite schist containing chloritoid. The general size of the deposit could not be discerned. As Stuckey (1928) pointed out, the pyrophyllite is considerably iron stained. This staining is probably caused by weathering of chloritoid and might not persist with depth. Currie Prospect: The Currie prospect is located almost on the northern county line, one mile east of the Jones prospect. This prospect lies east of the Glendon fault. The rock in this area is slate, in places, sheared to a sericite schist. Although Stuckey (1928) reported pyrophyllite occurred at this deposit, none could be found during this investi-gation. The old prospect pits are covered with over-growth and reveal little about the deposit. Standard Mineral Company Mine : The Standard Mineral Company mine is situated two and one-fourth miles southwest of Robbins. This deposit was 21 discovered in 1918, by Mr. Paul Gerhart, and min-ing commenced soon thereafter. This operation is the only pyrophyllite mine in the state worked under-ground. Ore is at present being removed from the eighth level, about 400 feet below the surface. The pyrophyllite zone is exposed in the mine pit for over 1300 feet continuing beyond the area map-ped (see Plate 3). The ore body dips northwest at 50 degrees to 70 degrees and lies in a zone of compli-cated reverse faulting. In places this faulting has repeated the pyrophyllite zone, making the mine-able ore body as much as 150 feet wide. The north-eastern half of the deposit is offset to the northwest by cross faulting. The ore body is surrounded by slate which has been sericitized for as much as 300 to 400 feet on either side of the deposit. Dry Creek Mine : The Dry Creek mine is located along the strike of the Robbins fault and lies two miles southwest of the Standard Mineral Company mine. The ore is exposed in two pits located 500 feet apart. It has developed along two thin parallel shear zones (see Plate 5). Ore bodies exposed in the southern pit lie to the northwest of the strike of the northern pit, indicating that the mineralized zone is offset by cross faults. The ore bodies pinch and swell along the strike of the faults, and rarely exceed 20 feet in width. The county rock is highly sericitized slate. Ruff Mine : The Ruff mine is located one and one-half miles southwest of Hallison. The ore body can be traced for over 180 feet. It occurs in a fault zone which strikes north 20 degrees east and dips north-west at 80 degrees. The southeastern limb of the ore body is displaced to the northwest by a cross fault which strikes north 45 degrees west and dips to the northeast at 75 degrees. The mineralized zone averages from 6 to 15 feet wide in the center, but narrows to the northwest and southeast, finally dying out along strike in these directions. The coun-try rock is an andesitic lithic tuff. Hallison Prospect : Pyrophyllite was discovered six tenths of a mile west of Hallison during the re-opening of an old gold mine (Stuckey 1928). At this locality several shallow pits have been dug along a quartz vein. The rock in contact with the quartz is a sericite schist containing a minor amount of pyrophyllite. The prospect is located in the shear zone of a north 70 degrees east trending fault, dip-ping northwest at 55 degrees. This fault forms the contact between felsic tuffs and slates. If any de-gree of mineralization took place in the slates along this fault there is a possibility of the existence of a workable deposit in the area. Sanders Prospect : The Sanders prospect is locat-ed on a hill northwest of the intersection of Cotton Creek and Cabin Creek. The top of this hill has recently been bulldozed along strike of the deposit for approximately 250 feet. This cut exposes seri-citized slate which becomes sericite schist near the zone of maximum shear of a north 35 degrees east trending fault, dipping 70 degrees northwest. Seri-cite developed along this fault can be traced from Cotton Creek northeastward for about 1000 feet. Quartz veins have been emplaced in the center of this fault zone. Pyrophyllite is developed adjacent to the quartz veins, and where it occurs in direct contact with the veins, forms radiating rosettes. The pyrophyllite zone rarely exceeds three feet in width. Weathered pyrophyllite outcrops are highly iron stained; unweathered pyrophyllite is relatively free from staining but contains excessive chloritoid. Origin of Pyrophyllite The pyrophyllite deposits of Newfoundland (Bud-dington, 1919), North Carolina (Stuckey, 1928) and California (Jahns and Lance, 1950) all occur in rocks of volcanic origin. Buddington (1919), Stuck-ey (1928), Vhay (1937), Jahns and Lance (1950), and Broadhurst and Council (1953) have all regard-ed the origin of pyrophyllite as hydrothermal re-placement. Hurst (1959) from a study of the mineralogy of Graves Mountain, Georgia believed that kyanite in the deposit formed under water deficient conditions at high temperature and pressure. The pyrophyllite is thought to have formed by the ingress of water along fractures partially converting kyanite to pyro-phyllite. Zen (1961) from a study of samples collected from various pyrophyllite deposits of North Carolina tended to disregard the effect of hydrothermal re-placement solutions on the formation of the pyro-phyllite bodies. The presence of three phase min-eral assemblage of the ternary system A12 3-H2 0- SiO.„ in his estimation, indicated water acted as a fixed component. However, he further noted that to say water acted as a fixed component did not com-pletely imply the absence of a free solution phase (hydrothermal solutions), such a phase could have existed, but certainly did not circulate freely through the system destroying the buffering mineral assem-blages. From a study of the occurrence of pyrophyllite in Moore County, certain similarities among the dif-ferent deposits became readily apparent. These de-posits are selective to rock type, occur in shear zones 22 of major longitudinal faults, are lenticular in out-line, have similar mineralogies, and are zoned. Rock Types: The major pyrophyllite deposits in the county occur in the slate unit. The wall rock in the White mine consists of alternating beds of slate and andesitic tuff, whereas the wall rock of the Ruff mine is composed entirely of andesitic tuff. It is interesting to note that both these rocks are com-posed of easily sheared water laid, volcanic sedi-ments. No pyrophyllite deposits have been observed in either felsic tuffs or mafic tuffs. This is not meant to imply that pyrophyllite does not occur in these rocks, because it is reported in altered rhyolites in Newfoundland (Vhay, 1937), and in felsic tuffs in North Carolina (Stuckey, 1928) ; and Broadhurst and Council, (1953). On the other hand, the ability of the slates and andesitic tuffs to readily shear and develop schistosity must have been a factor in the formation of pyrophyllite. Faults : Stuckey (1928) recognized that the pyro-phyllite deposits of Moore County occurred in shear zones. During this investigation it was found that the pyrophyllite deposits north of Glendon and southwest of Robbins occur in the shear zones of the Glendon and Robbins faults. Although not studied in as much detail, the Sanders and Ruff deposits also occur in fault zones. Some of the pyrophyllite pits contain as many as four parallel northeast trending faults. The ore bodies in the White, Standard Mineral Company, and Dry Creek mines have all been offset by cross faults. Pyrophyllite has not developed along these cross faults indicating that they developed after pyrophyl-litization. Low angle thrust faults were observed in the hanging wall of the Womble and White pits. Cross faults in the White pit do not offset the thrust sheet, indicating that thrusting occurred after cross fault-ing. Outline of Pyrophyllite Bodies : In 1928 Stuckey noted that the pyrophillite bodies were lenticular in outline. This investigation revealed that the ore bodies pinch and swell along their whole length eventually dying out along strike. It also revealed that the bodies all trend northeast and pitch north-west, their development being controlled by major northeast trending, northwest dipping longitudinal faults. Subsurface information made available dur-ing this investigation indicates that the ore bodies not only pinch and swell along strike, but down dip as well. Mineralogy : The pyrophyllite deposits all contain the mineral pyrophyllite, sericite, kaolinite, quartz, hematite, and chloritoid. In addition, the fault zone at the Phillips, Womble and Snow properties contain small augen masses composed of pyrophyllite, topaz and diaspore. A sample of this material was col-lected at the Phillips property. Eldon P. Allen, a staff member of the Division of Mineral Resources, calculated percentages of each mineral present, using microscopic techniques, as follows : 27 percent pyro-phyllite, 36 percent diaspore, 37 percent topaz, and 1 percent fluorite. Diaspore has also been reported at the Sanders property (Stuckey, personal com-munication). The only crystalline radiating phyrophyllite ob-served was in contact with vein quartz at the Sanders Property. Fluorite crystals occur in the vein quartz intruding the fault zone at the Phillips Property. Pyrite cubes and chlorite masses are found in the sericitized wall rock at this site. The pyrite cubes are invariably coated by a tissue thin film of quartz, even though the host rock is not silicified. The pyrite cubes on the hanging wall side of this deposit have a rhombic dodechedral face which is absent in the cubic crystals of the footwall. Silicification is prevalent at the Phillips, Wom-ble, Snow, Dry Creek, and Standard Mineral Com-pany mines. Solutions which brought in this silica in places also introduced copper and gold. Silicified rock in the hanging wall of the Womble pit is stained with azurite and malachite. Silicified rock in the hanging wall of the Standard Mineral Com-pany's pit contains gold which was mined before pyrophyllite was discovered. Zoning : Each of the pyrophyllite deposits observ-ed in Moore County is zoned. Zoning was first noted by Broadhurst and Council (1953) , p. 9) who stated : "A large deposit can be divided into three arbitrary units : a very siliceous footwall, a highly mineralized zone, and a sericitic hanging wall". The outer zone, surrounding the deposits, is a highly sheared country rock, enriched with hematite, chlorite, and chloritoid, which rapidly grades into unaltered rock away from the deposit. The contact between the outer and middle zones is sometimes exceptionally sharp, and occasionally cuts across the regional schistosity. The second or middle zone is a sericite schist still exhibiting faint relic beddings and containing minor chloritoid. This middle zone contains silicified bodies and, in the Phillips pit, chlorite bodies as well as abundant zones of pyrite cubes. The contact between the middle and inner zones is exceedingly gradational and poorly defined. The inner zone is always composed primarily of pyro-phyllite with some sericite and minor chloritoid. 23 The highest grade pyrophyllite always occurs in the center of this zone in the area of maximum shearing. Schistosity increases toward the center of the inner zone, which is eventually displaced by faulting. These fault planes are almost invariably intruded by quartz veins. Several generalizations can be made about zoning in the pyrophyllite bodies. These are: Shearing increases inwardly until a zone of rupture is reached, the amount of pyrophyllite decreases outwardly, the amount of chloritoid increases outwardly, and seri-cite is best developed in the middle zone and de-creases both inwardly and outwardly. Therefore, the zoning in these deposits may be classified as: 1. An outer magnesian and iron enriched zone; 2. A potassium or alkali zone; and 3. A high alumina zone. Discussion and Conclusions : The bulk chemical composition of the pyrophyllite deposits is essentially the same as that of the country rock. All of the chemical elements present in the pyrophyllite de-posits are present in the country rock, with the ex-ception of fluorine, copper and gold. These elements are associated with quartz veins and silicified zones and were obviously brought in from an outside source. The pyrophyllite deposits could have formed in place, with either addition or subtraction of chem-ical elements, if the elements were properly segre-gated and recrystallized into new minerals. A pos-sible sequence of events in the formation of pyro-phyllite deposits might be as follows : 1. Intensive folding and low grade regional meta-morphism accompanied by faulting. 2. Establishment of a temperature water pres-sure gradient across the shear zone, with high tem-perature and pressure in the center diminishing toward the sides. This would cause growth of the lower temperature and pressure minerals chlorite, chloritoid and hematite in the outer zones; the higher temperature and pressure mineral sericite in the middle zone ; and the highest temperature and pressure minerals pyrophyllite, diaspore and topaz in the central zone. Water vapor within the system would give the individual iron mobility to move in or out, as the case may be, causing previously exist-ing minerals to be replaced selectively. 3. Invasions of quartz veins, accompanied by silicification and introduction of fluorite, copper car-bonates, gold and pyrite as a separate event. In addition, at the Sanders prospect, the quartz veins caused recrystallization of the pyrophyllite in con-tact with the veins. 4. Removement along many of the faults, accom-panied by shearing of the quartz veins. 5. Cross faulting. 6. Minor overthrusting in the areas around the Womble and White pits. Gold Mode of Occurrence : Many of the gold mines in Moore County were originally worked as placers. Later, as mining deleted the original stream concen-tration, mines were opened in the primary ore veins. The largest number of these deposits occur in highly sheared felsic tuffs on the northwest side of the Robbins fault along Cabin Creek. Some of the ore occurs in rich quartz veinlets. However, the majority is disseminated throughout the country rock on either side of the veins. The ore bodies usually strike northeast and dip northwest parallel to regional schistosity. Orthoclase feldspars have been observed in some quartz veins suggesting that they were emplaeed at high temperature. Pardee and Park (1948) con-sidered the gold lodes of the southeast as high tem-perature deposits formed at considerable depth. They suggested that they were emplaeed during the orogony which occurred at the close of the Carbon-iferous period. Gold Mines Clegg Mine: The Clegg mine is located one and one-half miles west of Robbins. It was originally operated as an open cut mine, but sometime after 1900, two shafts were sunk on the ore vein. The main or Gerhardt shaft reached a depth of 128 feet and the second shaft reached an estimated depth of over 110 feet. The ore was ground on Chilean mills and the gold recovered by passing it over riffle boxes. These boxes were eventually replaced by copper plates. The deposit strikes north 25 degrees east and dips northwest at 75 degrees. The gold is disseminated throughout an ore zone 12 feet wide. The country rock is a felsic tuff sheared to sericite schist. The ore body contains a network of small quartz veinlets and is cross cut by reportedly barren quartz veins. Wright Mine : The Wright mine lies approxi-mately 150 feet northeast of the Clegg Mine. Prior to 1862, a shaft of unknown depth was sunk on this property. A second shaft was completed by J. W. Wright to a depth of 60 feet before the mine was closed in 1912. After grinding the ore on Chilean mills, the gold was recovered in riffle boxes. 24 The ore vein at this mine is a continuation of the vein found at the Clegg mine, and was reported to vary in width from 11 to 20 inches. The ore is disseminated through, what appears to be, highly manganese stained fault gouge. Cagle Mine : The Cagle mine is located 1500 feet southeast of the Clegg mine. The date this mine was first opened is not known, but it is thought to have been' operated in 1865 by Charley Overton. The mine operated sporadically until about the turn of the century, when it was closed. An attempt to de,water the old workings was made in 1906, but since that time the mine has laid dormant. The first shaft, an inclined shaft, reached a depth in excess of 171 feet ; a second shaft, approximately 50 feet southwest of the first reached a depth of 265 feet ; and a third shaft, further southwest, reach-ed a depth of 180
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Title | Geology and mineral resources of Moore County, North Carolina |
Creator |
Conley, James F. |
Contributor | North Carolina. Division of Mineral Resources. |
Date | 1962 |
Subjects |
Geology--North Carolina--Moore County Mines and mineral resources--North Carolina--Moore County |
Place |
Moore County, North Carolina, United States |
Time Period |
(1954-1971) Civil Rights era (1945-1989) Post War/Cold War period |
Description | Five folded maps in pocket; Includes bibliographical references (p. 38-40) |
Publisher | N.C. Dept. of Conservation and Development, Division of Mineral Resources |
Agency-Current |
North Carolina Department of Environmental Quality |
Rights | State Document see http://digital.ncdcr.gov/u?/p249901coll22,63754 |
Physical Characteristics | viii, 40 p. : ill. ; 28 cm. |
Collection | North Carolina State Documents Collection. State Library of North Carolina |
Type | text |
Language | English |
Format | Bulletins |
Digital Characteristics-A | 8627 KB; 69 p. |
Series | Bulletin (North Carolina. Division of Mineral Resources) ; 76. |
Serial Title | North Carolina Geological Survey bulletin |
Digital Collection | North Carolina Digital State Documents Collection |
Digital Format | application/pdf |
Audience | All |
Pres File Name-M | pubs_geology_geologybasementrocks1993.pdf |
Pres Local File Path-M | \Preservation_content\StatePubs\pubs_geology\images_master\ |
Full Text | C / North , state Library ^ North Carolina Department op Conservation and Development Hargrove Bowles, Jr., Director Division of Mineral Resources Jasper L. Stuckey, State Geologist Bulletin 76 Geology and Mineral Resources of Moore County, North Carolina By James F. Conley Raleigh 1962 North Carolina Department of Conservation and Development Hargrove Bowles, Jr., Director Division of Mineral Resources Jasper L. Stuckey, State Geologist Bulletin 76 Geology and Mineral Resources of Moore County, North Carolina By James F. Conley Raleigh 1962 . Members of the Board of Conservation and Development Governor Terry Sanford, Chairman Raleigh R. Walker Martin, Vice Chairman Raleigh John M. Akers Gastonia Dr. Mott P. Blair Siler City Robert E. Bryan : Goldsboro Mrs. B. F. Bullard . Raleigh Daniel D. Cameron : . Wilmington Mrs. Fred Y. Campbell r Waynesville Dr. John Dees I Burgaw William P. Elliott, Sr Marion E. Hervey Evans, Jr Laurinburg E. R. Evans Ahoskie E. D. Gaskins Monroe Andrew Gennett Asheville Luther W. Gurkin, Jr Plymouth Woody R. Hampton , Sylva Charles E. Hayworth , High Point Gordon C. Hunter ___.__Roxboro Roger P. Kavenagh, Jr ... Greensboro Carl G. McGraw Charlotte Lorimer W. Midgett Elizabeth City Ernest E. Parker, Jr Southport R. A. Pool .' Clinton Eric W. Rodgers : Scotland Neck Robert W. Scott Haw River W. Eugene Simmons Tarboro James A. Singleton Red Springs J. Bernard Stein Fayetteville Charles B. Wade, Jr Winston-Salem 11 Letter of Transmittal Raleigh, North Carolina May 2, 1962 To His Excellency, Honorable Terry Sanford Governor of North Carolina Sir: I have the honor to submit herewith manuscript for publica-tion as Bulletin 76, "Geology and Mineral Resources of Moore County, North Carolina", by James F. Conley. This report contains the results of detailed investigations of the geology and mineral resources of Moore County and should be of value to those interested in the geology and mineral re-sources of Moore County and adjacent areas. Respectfully submitted, Hargrove Bowles, Jr. Director in Contents Page Introduction 1 Location and area 1 Purpose and scope 1 Geography ^ 1 Culture 1 Climate 1 Physiography 2 Topography 2 Drainage 2 9> Geology - 2 The Carolina Slate Belt 2 Stratigraphy 3 Lower volcanic sequence 4 Felsic tuffs and flows - 4 Mafic tuffs 4 Andesite tuffs 5 Volcanic-sedimentary sequence 6 Slates 6 Environment of deposition 6 Structure 7 Folds 7 Troy anticlinorium 7 Minor folds 7 Faults 7 Longitudinal faults 7 Glendon fault 7 Robbins fault 8 Other longitudinal faults 8 Cross faults 8 iv Page The Deep River Triassic Basin 8 Stratigraphy 9 Pekin formation 9 Cumnock formation 9 Sanford formation 10 Unnamed upper conglomerate 10 Triassic diabase 10 Environment of deposition 11 Structure 12 Folds 12 Faults 12 Border faults 12 Jonesboro fault 12 Western border fault 12 Cross faults 12 Longitudinal faults 13 The formation of the Deep River basin 13 The Coastal Plain 13 Stratigraphy :. .13 Upper Cretaceous Tuscaloosa formation 13 Lower member 14 Upper member : 15 Environment of deposition 16 Tertiary Pinehurst formation 18 Stratigraphy 18 Environment of deposition 19 Structure 19 Other Deposits . 20 Terrace gravel 20 Alluvium 20 Economic Geology 20 Pyrophyllite 20 Pyrophyllite mines and prospects 20 McConnell prospect 21 Jackson prospect 21 v Page Bates mine 21 Phillips and Womble mine 21 White mine : 21 Jones prospect 21 Currie prospect 21 Standard Mineral Company mine 21 Dry Creek mine 22 Ruff mine ' 22 Hallison prospect 22 Sanders prospect 22 Origin of pyrophyllite — : 22 Rock types 23 Faults . . 23 Outline of pyrophyllite bodies 23 Mineralogy 23 Zoning 23 Discussions and conclusions 24 Gold -24 Mode of occurrence 24 Gold mines 24 Clegg mine 24 Wright mine 24 Cagle mine 25 Red Hill mine : 25 Allen mine 25 Burns mine 25 Brown mine : 25 Shields mine 25 California mine _ 25 Dry Hollow placer mine 26 Jenkins mine : 26 Richardson mine 26 Monroe mine 26 Bell mine . 26 Ritter mine 26 Donaldson mine , 26 vi Page Copper 27 Coal i 27 Quality and reserves .1 27 Coal mines 27 Murchison mine _- 27 Garner mine 27 Black shale and black band 28 Stone 28 Sand and gravel 28 Pinehurst formation 28 Terrace gravel 28 Upper member of Tuscaloosa formation 28 Triassic gravel 28 High silica quartz : 29 Vein quartz : -29 Unconsolidated quartz sands and gravels 29 Clay . 29 Residual kaolin in the Carolina Slate Belt 29 McEnnis pit 29 William pit 30 McDuffy pit 30 Other clay in the Carolina Slate Belt 30 Pottery clay 30 Hancock pit 30 Cagle mine clay 30 Sedimentary clay in the Deep River basin 30 Sedimentary kaolin in upper member of the Tuscaloosa formation 31 Acknowledgements 31 References cited 38 vn Illustrations Plates Plate 1. Geologic Map of Moore County in pocket Plate 2. Geologic Map of Pyrophyllite Deposits, Glendon in pocket Plate 3. Geologic Map, Standard Mineral Company Pyrophyllite mine, Robbins in pocket Plate 4. White Pyrophyllite Mine, Glendon in pocket Plate 5. Geologic Map of Dry Creek Pyrophyllite mine in pocket Plate 6. Photomicrographs of Typical Volcanic Rocks page 32 Plate 7. Photographs of Typical Rock outcrops page 34 Plate 8. Photographs of Typical Rock outcrops page 36 vin GEOLOGY AND MINERAL RESOURCES OF MOORE COUNTY, NORTH CAROLINA By James F. Conley INTRODUCTION Location and Area Moore County is located in the south central part of North Carolina, between 35 degrees 04 minutes and 35 degrees 31 minutes north latitude and 79 degrees 12 minutes and 79 degrees 46 minutes west longitude. The county is irregular in outline with much of its boundary following streams and other natural features. It is bounded on the north by Randolph and Chatham counties ; on the east by Lee, Harnett, and Cumberland counties ; and on the west by Richmond and Montgomery counties. Scotland County lies immediately to the south, but has a common boundary at only one point. Moore County contains about 862 square miles and ranks 18th in size among the 100 counties of the State. Purpose and Scope A geologic mapping program was initiated in Moore County, North Carolina in the fall of 1959 by the North Carolina Division of Mineral Resources. The purpose of this research program was : (1) map the geology in as much detail as time permitted; (2) locate both the active and abandoned mines, study their economic possibilities, mode of origin and relationship to the regional structure; and (3) attempt to locate new mineral deposits which might be of economic value. Only the southern half of ,the county is covered by topographic maps. Therefore, a base map for the northern half was prepared from aerial photo-graphs at a scale of one inch equals one mile. The geology was plotted directly on contact prints and transferred to the base map. In the area underlain by rocks of the Carolina Slate Belt, outcrops vary from poor to non-existant and in several instances saprolite and soils had to be relied on to deduce the underlying rock type. Outcrops in the Coastal Plain are better exposed, except in a few instances where drainage is poorly developed. The northern part of the Triassic Deep River basin was mapped by John A. Rinemund (1955) during the period 1946-1949. Portions of his map are reproduced as part of the geologic map accompanying this report, with only minor changes. GEOGRAPHY Culture Moore County was established on July 4, 1784, from land which originally comprised part of west-ern Cumberland County. An additional tract bound-ed by James Creek, Little River, Hector Creek, and the Harnett County line was transferred from Hoke County in 1959. The county was named in honor of Alfred Moore, a military colonel in the American Revolution. Carthage, located near the center of the county, was established as county seat in 1803 and has served in that capacity since. Other principal towns include Aberdeen, Pinehurst, Robbins and Southern Pines. The county is served by three railroads. The Sea-board Air Line Railroad passes through the towns of Cameron, Vass, Southern Pines, Aberdeen and Pinebluff and is the main north-south route. The Norfolk Southern Railway has two east-west lines which serve the area. One crosses the northern part of the county passing through Glendon and Robbins, and the other, located in the southern part, passes through Aberdeen, Pinehurst and West End. From Aberdeen, southward, the area is served by the Rockfish and Aberdeen Railroad. A network of federal, state and county roads provide easy access to all parts of the county. In addition, regularly scheduled airlines operate out of Knollwood Airport, located a few miles north of Southern Pines. Moore County has a well balanced economy and a great variety of income-producing resources. Among the major of these are agriculture, mining, recrea-tion, and retail and wholesale trades. Climate Moore County is noted for its hot summers and mild winters, which make it a "mecca" for winter golfing and equestrian sports. The mean annual temperature is 61.1° F. The summer temperature averages 73.2° F; the winter temperature raverages L 50.2° F. The average precipitation is 44.61 inches, most of which occurs in the spring and early sum-mer (U. S. Weather Bureau, 1961). Physiography Moore County contains parts of two of the major physiographic provinces of the United States. The northern two-fifths of the county lies within the Piedmont Plateau province, locally referred to as the "clay country", whereas the southern three-fifths of the area is in the Sandhills subdivision of the Atlantic Coastal Plain province. In the area where the softer unconsolidated ma-terials of the Coastal Plain come in contact with the more resistant rocks of the Piedmont, there is a relatively narrow transition zone which in other places is marked by an abrupt change in relief. This contact is referred to as the Fall Line or Fall Zone. The Fall Zone occurs in Moore County as an uneven contact from near White Hill at the northeastern boundary westward through Carthage to a point on the western boundary about two miles north of Highway N. C. 211. In contrast to other areas, the Fall Zone in Moore County is a conspicuous topo-graphic ridge which forms a drainage divide be-tween northeast and southeast flowing streams. A third physiographic subdivision is the Triassic basin which lies in a northeast-southwest direction across the county. This depression or trough is about 10 miles wide and is tarecable from the north-east corner of the county southeastward to Harris, where it is covered by the sediments of the Coastal Plain. Even where covered by the Coastal Plain, the area underlain by Triassic sediments is lower than the surrounding countryside. The Triassic basin contains relatively soft sedimentary rocks which are much less resistant to erosion and have been removed at a more rapid rate than the crystal-line rocks of the uplands to the west. Topography Moore County is an area of contrasting topography. The uplands, underlain by crystalline rocks range in elevation from 600 feet above sea level in the north-western part of the county to only 300 feet in the northeastern part. Topography is typical of the Piedmont with rounded hills and V-shaped valleys. The hilltops rise from 75 to 100 feet above the valley floors, with a few rising as high as 150 feet. The Triassic basin ranges in elevation from 250 to 500 feet. The eastern and western rims of the Triassic basin lie as much as 250 feet above its floor and form prominent escarpments. From the escarpments the land slopes rapidly to the basin floor. Northeast trending ridges of low relief occur in the basin. These usually do not rise more than 75 feet above the valleys. Valleys in the Triassic basin are wider than in the uplands and some con-tain floodplain deposits. The average elevation of the Coastal Plain is about 400 feet; however, it ranges from 500 feet along its northern limits to less than 190 feet in river valleys at the extreme eastern tip of the county. The Coastal Plain is sculptured into alternating flat-topped ridges with convex sides that rise as much as 150 feet above broad, flat valleys filled with floodplain deposits. This topography is typical of the Sandhills region. Relief is considerably greater than found in the Coastal Plain outside of the Sand-hills. Drainage Moore County is drained by three major streams; Deep River, Little River, and Drowning Creek. Deep River enters the county along its north-central border and flows in a semicircle leaving the county at its northeastern corner. It drains almost all of the northern half of the area and has several major tributaries, including Bear Creek, Buffalo Creek, Falls Creek, McLendons Creek and Governors Creek. Little River heads up in central Moore County and flows eastward draining the central and east-central part of the area. Its main tributaries are Crane Creek, James Creek and Nicks Creek. The southwestern and southern boundary of the county is formed by Drowning Creek, which also drains this area. Its major tributaries are Jackson Creek, Horse Creek, and Aberdeen Creek. GEOLOGY The Carolina Slate Belt The northwestern part of Moore County is under-lain by low-grade metamorphic rocks of volcanic and sedimentary origin. The area in which these rocks crop out is known as the Carolina Slate Belt. The name Carolina Slate Belt was first applied by Nitze and Hanna in 1896. This name is a misnomer and should be replaced because the predominant rocks are not slates, and they do not form a belt. West of Moore County they are dominantly argil-lites, but in the county they are mostly phyllites with some slates. Although the outcrop area ap-pears as a belt, it is now known that these rocks extend under the Coastal Plain for a considerable distance. This is indicated by oil-test wells drilled in Bladen and Pender Counties, which bottomed in these rocks. In 1822 Olmstead described novaculite, slate, hornstone, and talc from areas now known to be underlain by the Carolina Slate Belt. In 1825 he referred to the "Great Slate Formation", which "passes quite across the state from northeast to southwest, covering more or less the counties of Person, Orange, Chatham, Randolph, Montgomery, Cabarrus, Anson and Mecklenburg". He described the rocks of this "formation" as consisting of clay slate or argillite porphyry, soapstone, serpentine, greenstone and whetstone. Eaton (1820) in a re-port on gold in North Carolina, added "talcose slates" to the list of rocks occurring in the belt. He stated that they occur in association with novacu-lite. Ebenezer Emmons (1856) probably one of the most competent geologists of his time, placed these rocks in his Taconic system which he divided into an upper and a lower member. He considered these rocks amongst the oldest in this county. The upper member consisted of clay slates, chloritic sandstones, cherty beds, flagstones, and brecciated conglom-erates. The lower member consisted of talcose slates, white and brown quartzites and (on his cross section, Plate 14, he added) conglomerate. Emmons, not recognizing volcanic rocks in his series, considered them water-laid sediments. The divisions of his system into an upper and a lower member is used, with modifications, in this report. Kerr (1875) described the rocks of the Carolina Slate Belt and proposed that they were of Huronian age. Williams (1894) first recognized volcanic rocks in the Carolina Slate Belt. Becker (1895) publish-ed a paper recognizing the presence of volcanic rocks in the sequence and proposed that they were Algoncian age. Nitze and Hanna (1896) recognized volcanic - rocks interbedded with the slates that they proposed were laid down during times of volcanic outbursts, followed by inactivity during which time slates were deposited. They noted that some of the rocks had true slaty cleavage, whereas others were truly schis-tose. They believed these rocks were altered by dynamo-and-hydro-metamorphism. Weed and Watson (1906) studied the Virgilina copper deposits and proposed that the country rocks were metamorphosed andesites. The age was thought to be Precambrian. Laney (1910) described the Gold Hill Mining District of North Carolina. In this report he divid-ed the rocks into slates with interbedded felsic and mafic flows and tuffs. He stated that the slates differ from the fine, dense tuffs only in the amount of land waste they contain, indicating that the slates, in part, were derived from volcanic material. He did not define "land waste", nor did he explain how it might be recognized. He stated that the rocks all show much silicification and are only locally sheared. He proposed that a major fault, the Gold Hill fault, separated the igneous rocks to the west from the slates. Pogue (1910) described the Cid Mining District, and Laney (1917) described the Virgilina Mining District. Interpretations in these reports are, in general, repetitions of ideas as expressed in Laney's report of 1910. Stuckey (1928) presented a report which included a geologic map of the Deep River Region of Moore County. He divided these rocks into slates, acid tuffs, rhyolites, volcanic breccias, and andesite flows and tuffs. He noted that the schistosity dipped to the northwest and interpreted the structure as close-ly compressed synclinorium with the axes of the folds parallel to the strike of the formations. He stated (p. 23) "The minor folds dip steeply to the northwest side of the troughs and flatten out to the east. The synclinal troughs pitch and flatten out in places as is indicated by the way the slate bands, which are all synclinal in structure, occur in long narrow lenses often pinching out. This pinching and flattening indicates some cross folding". He noted the slates seem to have consolidated readily and to have folded as normal sediments; whereas, the tuffs and breccias remained in a state of -open texture and tended to mash and shear instead of folding. He stated that there is little evidence for faulting, although minor displacements amounting to a few inches were noted. Stuckey, from a com-parison of his investigation with work by Laney and Pogue, concluded that the rocks of the whole slate belt are of the same general types. He noted that metamorphism is not uniform throughout the area. Theismeyer and Storm (1938) studied slates near Chapel Hill that showed fine-graded bedding, and proposed that they represented seasonal banding. Theismeyer (1939) proposed that similar sediments found in Faquier County, Virginia, were deposited in pro-glacial lakes during late Precambrian and early Cambrian times. The bedding is thought to be seasonal "varves". In addition he proposed that "the Hiwassee slates of Tennessee and the slates in North Carolina, near Chapel Hill, belong to the same category; even may have been deposited more or less contemporaneously". Stratigraphy The rocks of the Carolina Slate Belt have been divided, by Conley (1959) and Stromquist and Con-ley (1959) in the areas covered by the Albemarle and Denton 15-minute quadrangles, into a lower unit composed of volcanic rocks, a middle unit com-posed of volcanic and sedimentary rocks, and an upper unit of volcanic rocks which unconformably overlies the two lower units. In Moore County only the lower and middle units appear to be present; however, some rhyolites in the area might belong to the upper unit. The exact stratigraphic relation-ships of some of the rocks in the county are in doubt because of the gradational nature of the contacts, a condition further complicated by intense folding and faulting and lack of outcrops. Lower Volcanic Sequence Felsic Tuffs and Flows : Rocks of the Lower Vol-canic sequence are the oldest rocks exposed in the county. This unit on the order of 3500 feet thick, is composed predominately of fine, usually sheared, felsic crystal tuffs. The tuffs vary in color from white or light cream to light grey. They weather white and sometimes white weathering rinds are ob-served on fresh rock. Topsoil developed on these rocks is a cream-colored silty loam; the subsoil is a white clay loam. The rocks are usually massive. However, in a small area on Mill Creek west of West Philadelphia, they contain obscure bedding planes. In thin section the tuffs are composed of quartz, orthoclase, and plagioclase, probably albite in com-position, in a fine groundmass of what appears to be cryptocrystalline quartz accompanied by sericite and kaolinite. Feldspars appear as clouded, angular lath-shaped fragments partly replaced by sericite. The sheared appearance is much more apparent in thin section than in hand specimen. The quartz grains are crushed and drawn out in the direction of shearing. The groundmass has a banded appear-ance resulting from segregation of kaolinite and sericite along planes of shear. Interbedded with the felsic crystal tuffs are felsic lithic-crystal tuffs, rhyolites, and mafic crystal tuffs. The contact between the felsic crystal tuffs and the felsic lithic-crystal tuffs usually is gradational with well defined contacts being the exception. The lithic-crystal tuffs have the same matrix composition as the crystal tuffs, but in addition contain grey por-phyritic, rhyolite fragments which range from one eighth of an inch to more than six inches in diameter. These fragments range from well rounded to highly angular masses ; others appear to be flattened. The groundmass is now composed of cryptocrystalline quartz, sericite and kaolinite. The phenocrysts con-sist of quartz and lath-shaped orthoclase and pla-gioclase feldspars, the latter varying in composition from albite to oligoclase. Some of the tuffs are welded and exhibit flow lines. They could easily be mistaken for rhyolites if it were not for the pres-ence of lithic fragments. The flow lines usually are well defined in thin section due to the development of sericite along the flow structures. The rhyolites occur in small outcrops in the ex-treme northwestern corner of the county near West Philadelphia and on the hill above the Dry Creek pyrophyllite mine. Rhyolites are difficuilt to differ-entiate from flow tuffs, even in unmetamorphosed rocks, and these may be flow tuffs. They are classi-fied as rhyolites on the basis of swirl flow banding, euhedral feldspar phenocrysts, and the absence of either broken crystal of lithic fragments. The rhyolites are porphyritic, containing visible feldspars up to one-sixteenth of an inch in length. They are light grey in color, weathering to chalky white on the surface. They are exceedingly dense, emitting a metallic ring when struck with a hammer. This rock usually is not sheared even when tuffs on either side of some outcrops have suffered consid-erable shearing. They contain prominent swirl-banded flow lines which are accentuated by weather-ing. Because of their resistance to weathering the rhyolites form elongate hills. Soils developed on the rhyolite are extremely shallow, ranging from 12 to 15 inches in thickness. In thin section, the rhyolites are composed of ag-gregates of unoriented, interlocking, angular, quartz grains; untwinned orthoclase; and albite and carls-bad twinned oligoclase. The groundmass is exceed-ingly fine and can not be resolved to individual crys-tals, but appears to be an interlocking network of cryptocrystalline quartz, sericite and kaolinite. Mafic Tuffs: The mafic tuffs shown on the geo-logic map (Plate 1) are not limited to any one rock sequence, but are found interbedded with the felsic tuffs, and andesitic tuffs of the Lower Volcanic sequence as well as slates of the overlying Volcanic- Sedimentary sequence. However, mafic tuffs are more frequently associated with the andesitic tuffs. Evidently, outburst of mafic ejecta occurred over a considerable span of geologic time. Because of the lithologic similarity of the mafic tuffs they are all shown, for convenience, as the same color on the map. These rocks in general are andesitic in composi-tion, but contain some material that might be classi-fied as basalt. They are composed of lithic frag-ments ranging from one-sixteenth of an inch up to eighteen inches in diameter, and crystal fragments, ranging from microscopic up to one fourth of an inch in diameter. From place to place, the ratio of crystals to lithic fragments is exceedingly variable, as is the size of the elastics making up the rock. The tuffs usually are sheared. They have a grey-ish- green or olive-green color when fresh, becoming dun-brown on weathering from the oxidation of their iron. Topsoils developed on these rocks are tan-colored silty loams; the subsoils are usually dark-brown to chocolate-brown colored heavy clay loams. In thin section the matrix of the rock appears to be made up almost entirely of chlorite bands strung out parallel to shearing. Feldspars have been alter-ed to sericite and kaolinite. In highly sheared rocks, phenocrysts have, been rolled parallel to schis-tosity and have an augen-like appearance. One thin section contained quartz masses that appear to be crushed, unoriented, and strung out parallel to schistosity. These quartz masses might be second-ary fillings of vessicles. The lithic fragments appear to be of different composition than the matrix of the rock. Some specimens are composed of a mesh of lath-shaped feldspar crystals about 0.02 of a millimeter in length with chlorite filling the interstices. Augite, not al-tered to chlorite, is present in rare isolated frag-ments. The groundmass of some of the fragments is composed of sericite and kaolinite rather than chlorite. In general, the rock is not bedded. However, in the area north of High Falls the mafic tuffs contain numerous interbeds of graywacke. These interbeds range from a few tens of feet to more than over a hundred feet in thickness. The graywacke is green-ish- grey when fresh, becoming light-brown on weathering. It is composed of quartz, feldspar, rock fragments, and a small quantity of argillaceous ma-terial. The rock exhibits graded bedding consisting of coarse sand, rock fragments up to two centimeters across, and intermixed fine sand at the base, which grades upward into fine sand at the top of the bed. The rock fragments, so prominent in hand specimen, are reduced in thin section to aggregate of kaolinite, chlorite and sericite. This suggests that the frag-ments are completely altered and are only recogniz-able in hand specimen by the preservation of relic structures. Andesite Tuffs : The andesite tuffs are about 2500 feet thick and are composed of interbedded crystal tuffs, lithic-crystal tuffs, argillaceous lithic conglom-erates, argillaceous beds and questionable flows. These tuffs are highly susceptible to shearing and usually exhibit axial plane cleavage. Many of them are sheared and pass into phyllites in which primary fragments are flattened and elongated in the direc-tion of movement. The andesite tuffs have a dis-tinctive greyish-purple color when fresh, and on weathering become a lighter purple. This coloring is due to primary hematite in the rock. Topsoil de-veloped on the andesite tuffs is a dark, red-clay loam and the subsoil is a dark-maroon to maroonish-pur-ple colored heavy plastic clay. , Crystal fragments in the more tuffaceous phases rarely exceed 40 percent of the composition of the rock. They consist almost entirely of lath-shaped feldspar fragments and rare euhedral crystals, rang-ing in length from microscopic to three millimeters. The feldspars are highly sericitized and are both carlsbad and albite twinned. Gross composition is ap-proximately that of andesine. In addition to feld-spar, lath-shaped masses of chlorite are also present. This chlorite probably represents altered amphibole and pyroxene. Quartz is rare in the crystal tuffs; however, one questionable flow tuff consisted of 30 percent of almost spherical quartz grains ranging up to two millimeters across. This is probably sec-ondary quartz filling vessicles. The interstices are filled with hematite which obliterates the ground-mass. Lithic-crystal tuffs are readily differentiated from argillaceous lithic conglomerate. The fragments are angular and the matrix contains crystal frag-ments in the lithic tuffs ; whereas, the fragments are rounded and the matrix is argillaceous in the lithic conglomerates. The rock fragments in both the tuffs and conglomerates are similar in composition. They rarely exceed two inches in diameter in the conglom-erates, but range up to ten inches across in the tuffs. Megoscopically these fragments are of two types. One is a massive aphanite, and the other is a crystal flow rock. Microscopically the aphanite fragments consist almost entirely of sericite and hematite; the flow-rock fragments appear as an aggregate of unoriented feldspar laths averaging about 0.02 of a millimeter in length in a matrix of hematite. Aside from flow lines and crystals, the original composi-tion and texture of the flow rock fragments are masked by hematite. The groundmass of the tuffs is so fine grained that it can not be resolved under the microscope. It appears to be composed predominately of elongate masses of opaque hematite, sericite, chlorite, and kaolinite. Epidote occurs sparingly in some thin sections. The matrix of the argillaceous rocks is even finer grained and also is obscured by hematite. Near the top of the stratigraphic section the ande-site tuffs become more argillaceous and bedding is observed more frequently. As the contact with the overlying slates is approached, graded bedding, so common in the slates, begins to predominate. Volcanic-Sedimentary Sequence Slates : The slates are about 6,000 feet thick and form the basal unit of the Volcanic-Sedimentary se-quence? They attain the greatest elevation of any stratigraphic unit found in Moore County? There is no sharp contact between this rock and the under-lying andesitic tuffs, but there is a gradational strati-graphic change from tuff to slate. Fine graded bed-ding, resembling varved bedding, is a characteristic of the slates. The bedding planes vary from one-sixteenth to one-fourth of an inch in thickness. Axial plane cleavage usually is more pronounced than bed-ding. The fresh slate is dark grey in color and weathers to ocherous reds and yellows. Topsoils are usually light brown-colored silts; whereas, subsoils are light red silty loams. In thin section graded bedding is easily observed. It consists of a silt layer at the bottom which grades upward into clay layer. The silt sized particles pre-dominately consist of quartz grains as well as some feldspar and what were probably ferromagnesian minerals, now chloritized. The clay layers are now predominately sericite. The slates outcropping in the eastern part of the county, along the western contact with the Triassic basin, contain interbeds of graywacke sandstone, which in places make up as much as fifty percent of the rock. These graywackes have a different composition and texture than those interbedded with the mafic tuffs. They are greyish-green when fresh and weather light maroon. They usually appear to be massively bedded; however, closer inspection reveals thin bedding planes and graded bedding ranging in size from sand at the bot-tom to silt at the top. The rock is composed of equal parts of chloritized rock fragments and quartz with occasional grains of albite-twinned sericitized feld-spar which ranges in composition from oligoclase to andesine. The rock varies in composition from the base to the top of the graded beds. The matrix fill-ing the interstices between the sandgrains in the lower parts of the beds consist of about equal parts sericite and kaolinite with a trace of chlorite. As the beds become finer grained toward the top, chlo-rite increases until the upper silt fraction of the bedding is composed of approximately sixty percent chlorite, fifteen percent sericite, fifteen percent kao-linite and ten percent quartz. Environment of Deposition The Lower Volcanic sequence is thought to be vol-canic ejecta deposited on land. This is indicated by 6 the general angularity of lithic and crystal frag-ments and the general lack of sorting in the sedi-ments. Pillow structures, which only form in subaqueous flows, are not present in the interbedded rhyolites, even though flow lines are well preserved. If pillow structures had developed, they should be as well pre-served as the flow lines. The presence of welded flow tuffs also suggest subaerial deposition because it is unlikely these rocks could have retained enough heat to flow and weld if they were deposited in water. The tuffs on Mill Creek contain bedding and might be water laid. However, air laid tuffs often contain bedding and are deposited in water. The presence of graywacke interbeds in the mafic tuffs suggest an aqueous en-vironment and turbidity currents. These gray-wackes were probably, for the most part, derived from reworking of the mafic tuffs. The coarse mafic-lithic breccias and mafic crystal tuffs, so commonly interbedded with the andesitic tuffs, were evidently blown out of volcanoes and deposited directly in water without reworking. The numerous rounded lithic fragments, bedding planes, and fissle graded bedding suggest that the andesite tuffs were water laid. The presence of inter-bedded lithic-crystal tuffs and argillaceous lithic conglomerates of essentially the same chemical composition suggests that these rocks were derived from the same source. One probably represents vol-canic ejecta deposited directly in water without re-working, and the other a reworked sediment. The gradual increase in graded bedding toward the contact with the overlying slates suggest a change in environment from shallow to deep water. The andesite tuffs are thought to represent a transi-tion unit and a transition environment between the terrestial tuffs and flows of the Lower Volcanic sequence and the deep-water sediments of the over-lying Volcanic-Sedimentary sequence. The slates were deposited in quiet water, below wave base. This is indicated by the fine graded bedding which could only develop in quiet waters. The mechanism which produces fine graded bed-ding is not thoroughly understood. Theismeyer (1939) proposed that the slates were varved sedi-ments deposited in pro-glacial lakes during late Pre-cambrian or early Cambrian times. No glacial de-posits have been identified in the rocks of the Caro-lina Slate Belt and this theory is not acceptable. It has been suggested that varve-like graded bed-ding can only occur in water of low salinity because of flocculation. This is indicated by Fraser's (1929) experimental studies which showed the maximum salinity permitting the formation of varves of coarse clay to be about one fiftieth that of sea water. Petti-john (1949) stated that graded bedding occurs in sediments from Precambrian to the present and sug-gested that flocculation by sea water is a doubtful concept. Kuenen and Menard (1952) believed that graded bedding in graywackes is caused by turbidity currents and can occur in normal sea water. Two methods are proposed which might produce graded bedding in the slates. One postulates that the sediments were derived from silt and clay sized ash blown out of volcanoes. The larger sized par-ticles would immediately settle out of the air allow-ing them to be deposited in the water first. The smaller sized particles Would be thrown higher in the air and, buffeted by air current and take longer to settle out. This would produce a graded sediment due to air sorting before the material reached the water. The second method postulates that the grad-ed bedding was produced by turbidity currents. During rainstorms, streams would become charged with sediments. Upon reaching the basin of depo-sition, the water charged with sediments would be more dense than water in the basin; and would move slowly down the sub-aqueous slope as a weak turbidity current. As this current moved outward it would deposit a silt layer. As it lost its turbidity and velocity, the clay sized particles would gradually settle out on top of the silt layer. The presence of graywacke sandstones containing graded bedding adds strength to the turbidity current theory, be-cause graywackes are now usually regarded as' tur-bidity current deposits (Pettijohn 1957). Structure Folds Troy Anticlinorium : The major structure in Moore County is the Troy Anticlinorium, which trends in a northeast-southwest direction and plunges toward the southwest. This structure has been traced from southern Montgomery County to northern Randolph County. The anticlinorium is over 30 miles wide, lying between the Pee Dee River on the west and western Moore County in the east. The axis of the fold is located near Troy, Montgom-ery County, and the southeastern limb occupies northwestern Moore County. The felsic tuffs of the Lower Volcanic sequence crop out in the center of the structure, whereas the overlying andesite tuffs and slates dip off its southeastern flank. Minor Folds : A series of usually double-plunging anticlines and synclines, varying in wavelengths from one to three miles are developed on the south-east flank of the Troy anticlinorium. These folds are overturned to the southeast and cleavage developed parellel to the axes of the folds dips monotonously to the northwest at angles varying from fifty-five to seventy degrees. Schistosity and shearing increased from northwest to southeast across the county. In the northwestern part of the county the Lower Vol-canic sequence dips under the overlying rocks but reappears in the center of anticlinal folds across the central and southwestern part of the county. The slates, the youngest Carolina Slate Belt stratigraphic unit found in Moore County, occupy the center of a number of overturned synclines in the central and eastern part of the area. The slates are contorted into a series of undulating open folds varying in wavelength from ten to thirty feet across. These folds probably developed due to plastic flowage within the slates during regional folding. Faults Faults can be divided into two groups; namely, northeast trending longitudinal faults developed parallel to the axes of folds, and northwest trending cross faults. Because of slippage parallel to the axes of overturned folds, many of the longitudinal faults are reverse in nature. The zones of displace-ment along the major northeast trending faults usually have been intruded by quartz veins and are occasionally silicified and mineralized. The quartz veins and silicified zones are invariably sheared, indicating movement occurred along these faults after intrusion of the quartz veins and silicifica-tion. The cross faults have displaced the longitudinal faults in a number of places, clearly indicating that they developed after the longitudinal faults. Major movement along the cross faults was strike slip-page. Along the Deep River in the northern part of the county these cross faults can be traced into the Triassic basin. The cross faults have displaced the Carolina Slate Belt units as much as a mile along the strike, but have displaced Triassic rocks only a few hundred feet. This indicates the major movement took place in pre-Triassic time with a later movement of much smaller scale taking place after deposition of the Triassic sediments. Longitudinal Faults Glendon Fault: One of the major longitudinal faults in the area is the Glendon fault. It lies ap-proximately three miles northwest of Glendon and can be traced from the northern county line south-eastward to just north of Robbins. It strikes north 60 degrees and dips 60 to 70 degrees northwest. Drag folds indicate that it is a reverse fault, with movement from northwest to southeast. It is offset by several cross faults along its length. A wide mineralized shear zone containing workable pyro-phyllite deposits accompanies the fault. Movement along the fault has placed the andesite tuffs in con-tact with the slates, except north of McConnell, where it has placed felsic tuffs underlying the ande-site tuffs in contact with the slates. This suggests that the throw in this area must be in the order of several thousand feet. Robbins fault: The Robbins fault passes through the western city limits of Robbins and is traceable from approximately one mile north of Robbins, southeastward to approximately one mile northeast of West Philadelphia. It trends north 60 degrees east and dips northwest at approximately fifty de-grees. Drag folds indicate that it too is reverse in nature and the hanging wall to the northwest moved upward over the footwall to the southeast. The shear zone accompanying this fault is as much as a mile wide and contains pyrophyllite and gold de-posits. The reverse nature of this fault and pres-ence of pyrophyllite deposits along its trace sug-gests that it is the same type as the Glendon fault. In fact, if the strike of the Glendon fault were ex-tended to the southwest (see Plate 1), it would in-tersect the Robbins fault south of Robbins. Other Longitudinal faults : A horst structure, ly-ing between two north sixty-five degrees east trend-ing vertical faults, occurs in the area between Put-nam and Hallison. This structure places felsic tuffs of the Lower Volcanic sequence in contact with slates of the Volcanic-Sedimentary sequence. The andesite tuffs lying stratigraphically between the felsic tuffs and the slates are omitted, indicating a throw in the order of several thousand feet. This horst is adjoined on the northwest by a graben which lies between the fault north of Putnam and the Glendon fault. Cross faults : Vertically dipping northwest trend-ing normal cross faults, which strike from thirty to seventy degrees northwest, occur throughout the central and eastern part of the county. Some of these appear to be hinge faults; whereas others show strike slippage. A number of strike-slip faults along Deep River have a horizontal displacement varying from half a mile to over a mile. The Deep River has entrenched along these faults producing a series of parallel meanders. Southeast of Spies a pair of northwest-trending faults have produced a graben structure, downfault-ing andesite tuffs against felsic tuffs. A number of transverse faults have been intruded by diabase dikes. The dikes evidently were emplaced along zones of weakness; however, it is not under-stood why they preferred northwest trending faults and generally ignored those trending northeast. DEEP RIVER TRIASSIC BASIN The Deep River Triassic basin lies in a northeast-southwest direction across Moore County. In the northern part of the county it is bounded on either side by the Carolina Slate Belt. In the southern part of the county it. is overlapped by Coastal Plain sediments. Emmons (1852) on the basis of fossil and litho-logic evidence, concluded that the sediments of the Deep River basin were Triassic age. However, in 1856 he proposed that the lower sandstones and coal beds were of Permian age, because of the presence of Thecodant saurian teeth in some of the shales associated with the coal beds. Overlying sandstones were still considered Triassic age. Redfield (1856) found that the rocks in New Jer-sey, Eastern Pennsylvania and in the Connecticut Valley were Upper Triassic age and proposed that they be named the Newark group. He found that fossil vertebrates in Emmons collection were identi-cal to those occurring in the northern basins and cor-related sediments in the Deep River basin with the Newark group. Rocks of the Deep River basin consist of red, maroon, reddish-grey fanglomerates, conglomerates, sandstones and siltstones. In addition the basin contains coal beds and associated grey and black shales, mudstones, siltstones and sandstones. Emmons (1852) subdivided the stratigraphy of the Deep River Basin into three units. These are : 3. Sandstones, soft and hard with freestones, grindstone grits, and superior conglomerates ; crop-ping out along the eastern edge of the basin. 2. Coal beds and black slates with their subordi-nate beds and seams ; cropping out in- the center of the basin. 1. Inferior conglomerates and sandstones below the coal beds and black slates; cropping out along the western edge of the basin. This was a logical conclusion because the strata dip toward the eastern edge of the basin. Although he devised this classification, Emmons (1856) recog-nized marked resemblance between certain strata on the eastern and western part of the basin and suggested that they might be the same unit. In 1856 he repeated this classification in his text; however, on the map accompanying the report, in-serted an additional unit which he called "Salines" between the middle and upper units. Campbell and Kimball (1923) stated that the "Salines" are nothing more than drab shales, containing salt, above the coal beds, and belong with the middle division. Campbell and Kimball (1923) mapped and named Emmons' three units calling the lowest the Pekin formation, the middle the Cumnock formation and the upper the Sanford formation. Prouty (1931) discussed the formation of the Deep River basin. He proposed that it was caused by downwarping aided by development of an eastern border fault. Reinemund (1955) published a detailed study of the structure and stratigraphy of the Deep River basin with special emphasis on the economic geol-ogy. Stratigraphy Pekin Formation: Campbell and Kimball (1923) named the basal Triassic unit, the Pekin formation after a small town in southern Montgomery County. No type section or type locality was established, but they stated that it is best exposed on the road trend-ing due east from Mt. Gilead. The formation under-lies the western third of the Deep River basin in Moore County and is exposed along the western bor-der of the basin from Deep River southward to the Coastal Plain overlap. The formation is estimated to be from 1750 to 1800 feet thick. Its basal part is supposed to rest on the eroded- surface of the Caro-lina Slate Belt, (Reinemund 1955). To the south, along Drowning Creek, the western border of the basin is flanked by a lithic fanglomerate composed of angular to subrounded rock fragments, derived from the Carolina Slate Belt, ranging from one inch to over a foot in diameter. An elongate conglomerate bed, lenticular in out-line, resembling a shoestring sand lies along the western border of the northern part of the basin. This bed was extensively quarried before 1900 to make millstones, and is known locally as the Mill-stone Grit. The bed varies in thickness from 2 to 30 feet, and is composed of quartz pebbles, varying from one to three inches in diameter, in a matrix of coarse sand. The conglomerate is well cemented and the pebbles can be broken without being dislodged from the matrix. A paleosoil underlies the Millstone Grit in an out-crop on Highway N. C. 22 at the old Parkwood quar-ry. It is a grey, carbonaceous, partly-kaolinized clay containing numerous root impressions. East of the western border, the Pekin formation is composed of lenticular beds of red, brownish-red, and maroonish-purple clayey siltstones, sand-stones and occasional beds of brown or grey, medium to coarse grained, cross bedded, arkosic sandstones and conglomerates. Rare thin beds of claystone are also present. Many of the sandstones contain root impressions on weathered surfaces. Toward the center of the basin the sediments be-come finer grained, with siltstones predominating. To the southeast the sediments become progressively coarser, and frequently contain more arkosic beds as well as coarse-grained, grey-colored, cross-bedded sandstones. Cumnock Formation: Campbell and Kimball (1923) named the middle coal-bearing Triassic beds the Cumnock formation after the Cumnock mine. The type section was located in the main shaft of the mine. The Cumnock formation is exposed in northern Moore County from Deep River southward to the Coastal Plain overlap. On the road between Glendon and Carthage it-is repeated four times by faulting. In the north-central part of the basin the Cum-nock formation is 750 to 800 feet thick and consists of coal, black and grey shales, with thin sandstone beds in the middle and upper part (Reinemund 1955). The Pekin-Cumnock contact was placed by Emmons at the top of the last redbed below the coal beds, and the Cumnock-Sanford contact at the first redbed above the coal. The two workable coal beds occur about 200 feet above the base of the Cumnock formation. The lower coal bed, called the Gulf seam, has been found only at the Carolina and Black Diamond mines and lies from 25 to 45 feet below the second, or Cumnock bed (Reinemund 1955) . The Cumnock formation and associated coal beds is the thickest near the center of the basin, thinning rapidly toward the edges. The formation is best developed at Carbonton and Gulf and apparently thins rapidly to the southwest. This is indicated by the Cumnock coal bed which is reported to be 42 inches thick at Cumnock, but only 14 inches thick at an exposure at the Gardner mine. Campbell and Kimball (1923) noted the area, two miles wide, northwest of Carthage in which the Cumnock formation does not crop out. They postulated that this might be caused by either lateral gradation of the grey Cumnock strata into the red beds of the Pekin and Sanford formations, or down faulting, but seemed to favor faulting as the explanation. The Cumnock formation dips under the Coastal Plain sediments four miles southwest of Carthage, and has not been observed in outcrop south of the point. An exception to this might be the grey silt-stone and mudstone exposed in a stream valley one and one-half miles southwest of Eagle Springs, on the road to Samarcand Manor. Whether or not this is actually the Cumnock formation or a variation of the Pekin formation is open to question, because this exposure lies considerably north of a projection of the last Cumnock outcrop. It is thought that the reason the Cumnock formation does not crop out south of Carthage is because it is downfaulted along the continuation of the Governors Creek fault. The Cumnock formation reappears further to the south-west as indicated by a coal prospect located in Mont-gomery County near the Moore County line. Sanford Formation: The Sanford formation was named by Campbell and Kimbell (1923) after the town of Sanford and included all rocks above the Cumnock formation. The Sanford formation con-formably overlies the Cumnock formation, and in Moore County this contact might best be described as gradational. The Sanford formation is estimated to be from 3500 to 4000 feet thick (Reinemund 1955) and covers the eastern half of the Deep River basin. Reinemund (1955) stated that the Sanford formation contained few distinctive beds which can be traced over any appreciable distance. The beds are lenticular and laterally gradational. Measured sections would only apply to rocks in the immediate vicinity and correlation is not feasible over wide areas. The Sanford formation similar to the Pekin formation, is predominately a sequence of redbeds. It also is composed of sandstones, siltstones, con-glomerate and fanglomerate. To the southwest, the formation becomes progressively coarser and con-tains more frequently occurring beds of coarse arkosic sandstone. Fanglomerate crops out, in a belt varying in width from three-fourths to over a mile wide, along the southeastern edge of the basin. It is composed of unsorted rock fragments ranging from one-half an inch to more than a foot in diameter. These frag-ments were derived from rocks of the Carolina Slate Belt and usually are poorly indurated. Material filling the interstices between the fragments usually is composed of red and maroon sandstones and silt-stones. The fanglomerate shows very poor bedding ; however, the general dip of the rock can be ascer-tained by observing the orientation of tabular rock fragments. From the eastern border and toward the center of the basin, the fanglomerat grades lat-erally into conglomerate. In addition to the fan-glomerate, the Sanford formation contains well-defined lenticular beds of quartz conglomerate which are sometimes cross-bedded. These lenses usually grade into sandstones. Beyond the border of the basin the majority of the Sanford formation consists of interbedded red and maroon siltstones and sandstones. Claystones and shales are almost totally absent. The coarser sandstones are most prevalent along the eastern edge of the basin with siltstones becoming predominant toward the center of the basin. These sandstones are similar to the sandstones of the Pekin forma-tion, along the northwestern edge of the basin and contain numerous root impressions. Unnamed Upper Conglomerate: Northeast of Carthage a grey conglomerate lies on the eroded sur-face of the Sanford formation (see Plate 1). Prob-ably the best exposure is in a new road cut on a hill rising above the east bank of the east fork of Big Governor's Creek. The conglomerate consists of well rounded quartz pebbles, ranging in size from one-half to two inches in diameter, intermixed with a minor amount of coarse angular sand. In addi-tion it contains minor lenses of siltstone. The rock is poorly consolidated and usually is not stained with the red iron oxides as generally is the case with Triassic rocks. The Triassic age of the conglom-erate is well established because it has been intruded by a diabase dike. After observing this conglomerate, J. L. Stuckey informed the author that similar gravels occur near Apex, North Carolina. The Apex locality was visit-ed by Reinemund and Stuckey in 1948, at which time they reached the conclusion that the gravels were of Triassic age and appeared to be younger than the Sanford formation. It might be argued that these gravels are part of the Sanford formation because unconformable beds within the formation are relatively common. This possibility certainly cannot be ruled out. However, a better explanation is that these gravels probably are post Sanford floodplain deposits as indicated by the preservation of old stream channels. Triassic Diabase : Diabase dikes generally regard-ed to have been emplaced in late Triassic time, have intruded both the Deep River Triassic basin and the Carolina Slate Belt. In the Deep River basin a num-ber of dikes have intruded the Sanford formation northwest of White Hill. Dikes and large sills have intruded the Cumnock formation northeast and southeast of Glendon. Dikes occasionally occur in the Pekin formation west of Carthage. Diabase dikes have been mapped in the Carolina Slate Belt and are most numerous in the area between High Falls and Parkwood. 10 The diabase dikes in general trend northwest, with a few exceptions trending either north or northeast. These dikes dip either vertically or slightly to the northeast. They range in thickness from one to several tens of feet. Diabase dikes oc-curring in the Carolina Slate Belt are usually smaller than those in Triassic sediments. This leads to the conclusion that the magma could more easily intrude and incorporate the less resistant Triassic sedi-ments. The existence of low refractory shales and coal in the Cumnock formation might explain why large sills occur in this unit. Even where they in-trude Triassic sediments, the baked zones on either side of the diabases are rarely over twice the thick-ness of the dikes, and- in the Carolina Slate Belt these zones do not exceed a few inches. The baked zones usually are dark grey at the contact with dia-base, becoming reddish grey away from the contact. The diabases are exceedingly susceptible to spher-oidal weathering producing rusty boulders scattered through the surficial soil. Soil, developed on weath-ered diabase is a conspicuous dark-yellow brown, but occasionally is a dark-chocolate brown. During the field investigation for this report little attention was given to the petrography of the dia-base dikes. Reinemund (1955) studied the diabases in detail. He found that they contain the primary minerals olivine, plagioclase feldspars, varying from andesine to bytownite, augite, orthoclase and quartz ; the accessory minerals magnetite, ilmenite, pyrite, chromite, titanite, apatite, and basaltic hornblend; and secondary minerals antigorite, limonite, horn-blende, calcite, and magnetite. Olivine is usually present in varying amounts. The rock usually con-tains as much as two-thirds plagioclase and as much as one-third augite. In addition to normal diabase, gabbroic varieties composed of one-half olivine and one-third plagioclase and dioritic diabase composed of one-half plagioclase and one-third augite are present. Envioronment of Deposition Kryniene (1950) expressed the opinion that red color of the Triassic sediments was due to erosion of red soils in the source area. Reinemund (1955) essentially agreed with this, and added that the dark brown and red colors of the Pekin and Sanford formations indicated that the sediments were de-posited in a non-reducing environment. During the time of deposition of both the Pekin and Sanford formations fluvial conditions existed in the Deep River basin. At this time both the border faults had well defined scraps. Talus material ac-cumulated at the base of these scarps producing the fanglomerates found in the Pekin formation along the western edge of the basin and the Sanford formation along its eastern edge. From the edges toward the center of the basin, sediments of both formations become progressively finer grained. Reinemund (1955) stated that sedi-ments of the Pekin and Sanford formations were deposited by streams, as indicated by the cross bed-ding and the channel like form of some of the coarse grained sediments. Root impressions, commonly found in the sandstones of these formations, sug-gest that much of the area between the major stress channels was marshland. General coarsening of the grain size of the sediments to the southwest indicate that drainage within the basin was in that direction. Gradual sinking of the basin probably occurred during sedimentation by slight movements along the border faults, causing rejuvination from time to time of streams flowing into the basin. During the latter part of Pekin sedimentation the scarp of the Western border fault in the northern part of the county did not stand at elevations great enough to produce talus deposits. At this time, a stream, in-cised along the fault scarp, deposited the Millstone Grit. The occurrence of the Cumnock formation, with its black shale and coal beds in the center of the basin, represents a change from stream and shallow marshes, with rapid sedimentation along the mar-gins of the basin ; to a shallow lake, with slow sedi-mentation in the center of the basin. A shallow body of standing water could support a lush growth of vegetation. After death the organic remains would fall to the bottom of the lake and be protected from oxidization. Extremely slow sedimentation would allow accumulation of organic material of thickness and purity to form workable coal beds. After the basin had filled with sediments, streams meandered over its surface depositing the unnamed, upper gravels which overly the Sanford formation. It is suggested that deposition of parts of the Pekin, Cumnock and Sanford formations, as map-ped, might have occurred simultaneously. Only in areas of outcropping Cumnock formation can the names Pekin and Sanford formations be used as time-stratigraphic units. In these areas redbeds underlying and in direct contact with the Cumnock formation can definitely be called the Pekin forma-tion, and inversely, the redbeds overlying the Cum-nock formation belong to the Sanford formation. Because grey shales and coal beds of the Cumnock formation are limited to the center of the basin, redbeds deposited along the eastern and western margins of the basin during Cumnock time are most 11 likely mapped as Sanford and Pekin formations re-spectively. As no key horizons exist along the mar-gins of the basin, it would be best to regard what has been mapped in these areas as Pekin and San-ford formations as sedimentary facies rather than time-stratigraphic units. Structure Folds: The Deep River basin has been described by Campbell and Kimball (1923) and by Reinemund (1955) as a synclinal basin. In this paper the basin is considered a graben structure in which the beds dip monoclinally to the south-east. The syncline which Reinemund (1955) regarded as the axis of the basin occurs northeast of White Hill. Another small syncline lies along the west bank of McLen-don's Creek, where Highway N. C. 27 crosses the creek. Approximately eight tenths of a mile north of this area is located the axis of a small anticline. Folds of large magnitude have not been observed within the Deep River basin in Moore County. Faults: Reinemund (1955) found three ages of faults in the Deep River basin. The oldest is the Jonesboro fault or eastern border fault, which re-mained active during sedimentation ; the cross faults are next in age, developing after sedimentation had ceased ; and the longitudinal faults are the youngest. This is indicated by the fact that the cross faults have displaced the Jonesboro fault, but not the longi-tudinal faults. In turn, the longitudinal faults have offset the cross faults, but are not offset by the cross faults. Border Faults Jonesboro Fault : The Jonesboro fault was named by Campbell and Kimball (1925) after the town of Jonesboro. It forms the eastern contact of the basin placing Triassic sediments against the Carolina Slate Belt. Reinemund (1955) estimated that the maximum vertical displacement along this fault is on the order of 6000 to 8000 feet. The fault strikes north 35 degrees east in the northeastern part of the county, but changes to a more easterly direction south of Eastwood, where it assumes a strike of about north 60 degrees east. The fault plane dips to the northwest at an angle of about 65 degrees. Reinemund (1955) observed that the Jonesboro fault is displaced by cross faults, although no displace-ment along the fault was noted in Moore County. Western Border Fault : The Western Border fault forms the western contact of the basin and also places Triassic sediments against the Carolina Slate Belt. Campbell and Kimball (1923) did not recog-nize the Western Border fault, and Reinemund (1955, Plate 1) has only mapped a few discontinu-ous faults along the western border of the basin. Authors of both these papers suggested the sedi-ments wedge out to the northwest. They proposed the sediments were once more extensive in that direction, but have been eroded away. This concept might be true of other areas of the Deep River Basin but could not be applied in Moore County. If the Triassic sediments wedged out to the west, it would be expected that streams would have eroded through the Triassic mantle exposing rocks underly-ing the basin, producing a scalloped contact. The contact is not scalloped, it is an essentially straight line, suggesting a fault contact. In addition, the fanglomerate, exposed along the western border of the basin in the southern part of the county, indi-cates that the fault scarp in this area was once a significant topographic feature. Campbell and Kimball (1923) and Reinemund (1955) considered the Millstone Grit a basal con-glomerate. The buried soil under the Millstone Grit indicates that it is not a basal conglomerate and that Triassic sediments had been deposited and weathered before the conglomerate was laid down. The presence of this fault is further indicated by a gravity survey of the Deep River-Wadesboro Basin conducted by Mann and Zablocki (1961). They stated that in places the basin has graben like fea-tures, but suggest that throw of the Western Border fault in the Deep River basin is less than that of the Jonesboro fault. The Western Border fault is best exposed at the bridge across Deep River, north of Glendon, on the Glendon-Carthage road. It strikes north 30 degrees east and dips to the southeast at 60 degrees. North of Eagle Springs the fault is bent to a more westerly direction and strikes north 55 degrees east. The vertical displacement is unknown but it is thought to be in the same order of magnitude as that of the Jonesboro fault during time of sedimentation. How-ever, post depositional movement along the Jones-boro fault exceeded that of the Western border fault which remained stable, causing the strata to dip to the southeast. The Western Border fault has been displaced in numerous places by cross faults through-out its exposed area. Cross Faults : Northwest trending cross faults are found throughout the Deep River basin. As pre-viously mentioned, along the Western border some of these faults begin in the Carolina Slate Belt and end in Triassic sediments. The major displacement has been parallel to the strike. Vertical displace-ment is usually minor being on the order of a few 12 tens of feet and occasionally ranging over one-hun-dred feet. Reinemund (1955) noted the faults ex-tend to great depth because many of them have been intruded by diabase dikes. In Moore County the cross faults trend about north forty degrees west; however, in rare instances, they trend from north twenty degrees west to almost due north. The fault planes are usually at high angles approaching verti-cal and generally dip to the northeast. Longitudinal Faults : A series of northeast trend-ing step faults, including the Deep River, Governors Creek, and Crawleys Creek faults, lie in a northeast direction across the center of the Deep River basin. These faults have repeatedly exposed the Cumnock formation in the northeastern part of the county. The fault planes dip to the northwest at angles varying from 20 degrees to thirty degrees. The ver-tical displacement varies from five-hundred to over two-thousand feet. Displacement gradually becomes less to the southeast and all of the faults except the Governors Creek fault die out before they have an opportunity to dip under Coastal Plain sediments. It is thought that the Governors Creek fault con- - tinues across the southern part of the basin, and is a rotational fault with its hinge line near Carthage. The Western block moved down northeast of the hinge line, but up southwest of the hinge line. This explains why, along this fault line, the Pekin forma-tion is in direct contact with the Sanford formation in the southern part of the county and the Cumnock formation in the northern part of the county. The Formation of the Deep River Basin Campbell and Kimball (1923) concluded that the Deep River basin was caused by downwarping of the earth's crust. Sediments were deposited in this trough causing it to continue to sink. After down-warping and sedimentation ceased, the basin was faulted. Prouty (1931) agreed that the basin was caused by downwarping, but believed the Jonesboro fault developed soon after sedimentation began. He pos-tulated that movement along this fault continued sporadically until sedimentation ceased. This pro-duced a wedge shaped trough, with the thickest sedi-ments next to the fault, becoming progressively thinner away from the fault. The last movement along the Jonesboro fault, as well as the development of faults in the basin occurred after deposition. The present investigation indicates the Deep River basin in Moore County is a rift valley caused by downfaulting along the Jonesboro and Western Border faults. These faults are thought to have existed in Pre-Triassic time and were reactivated in Triassic time producing the basin. The sequence of event which produced the Deep River basin in Moore County are as follows : 1. Removement along the Pre-Triassic Jonesboro and Western Border faults, during Newark time, creating a graben trough. 2. Disruption of drainage and beginning of sedi-mentation. 3. Continued movement along the border faults and possible fractional movement along the cross faults with continued sedimentation. 4. Stabilization of the faults with cessation of sedimentation. 5. Removement along the Jonesboro fault, drop-ping down the eastern side of the basin and tilting the strata to the southeast, accompanied by active movement along cross faults. 6. Development of longitudinal tension faults in the center of the basin. 7. Intrusion of the diabase dikes, predominately along northwest trending cross faults in both the Carolina Slate Belt and Deep River Triassic basin. THE COASTAL PLAIN Stratigraphy Upper Cretaceous Tuscaloosa Formation: The Tuscaloosa formation is the basal Coastal Plain unit in Moore County. In this report it is divided into a lower and an upper member. The Tuscaloosa forma-tion was named by Smith and Johnson in 1887 after the city of Tuscaloosa, Alabama. L. W. Stephenson (1907) subdivided the Cretaceous of North Caro-lina into three formations. He called the basal unit the Cape Fear formation. He considered it Lower Cretaceous in age and correlated it with the Patux-ent formation of Virginia. He named the overlying unit the Bladen formation, (Black Creek formation in present terminology) and correlated it with the Tuscaloosa formation of Alabama. In 1912 he re-named the Cape Fear formation the Patuxent forma-tion and correlated it, on lithology, with the Patux-ent of Virginia and Maryland. Sloan (1904) named the sands and clays of sup-posedly Lower-Cretaceous age in South Carolina, the Middendorf Formation. However, Berry (1914) studied plant fossils from this formation and found that they were actually of Upper Cretaceous age. Cooke (1936) correlated the Middendorf formations 13 of South Carolina with the Tuscaloosa formation of Alabama and extended the Tuscaloosa into North Carolina. Horace G. Richards (1950) described the Tuscaloosa formation in North Carolina and stated that it occurred in southern Moore County. W. B. Spangler (1950) from a study of cuttings obtained from oil-test wells drilled on the North Carolina Coast, found that the subsurface contained both lower and upper Cretaceous beds. He applied the name Tuscaloosa formation only to beds of Eagle Ford-Woodbine age. P. M. Brown (1958) also found rocks of Woodbine and Eagle Ford age in the subsurface stratigraphy of the North Carolina Coastal Plain. These he assigned to the Tuscaloosa (?) formation. S. D. Heron (1958) mapped the basal Cretaceous outcrops between the Cape Fear River in North Carolina and the Lynches River in South Carolina. He returned to the Classifications of Stephenson and Sloan, dividing the Tuscaloosa formation into the Lower Cretaceous ( ?) Cape Fear formation and the Upper Cretaceous Middendorf Formation. He nam-ed the lower part of the Black Creek formation, be-low the Snow Hill member, the Bladen member. Heron (1960) stated, "The Middendorf is considered the updip facies of the Bladen member of the Black Creek formation and both of these formations have overlapped the Cape Fear formation." Groot, Penny and Groot (1961) collected samples containing plant microfossils from the Tuscaloosa formation of the Atlantic Coastal Plain, including one sample from the basal part of the lower member of the Tuscaloosa formation in Moore County. They found that the Tuscaloosa formation of the Atlantic Coastal Plain is Upper Cretaceous age, but slightly older than Senonian, although some Senon-ian species are present. Lower Member: The lower member of the Tus-caloosa formation is the basal unit of the Coastal Plain sediments in Moore County. It rests uncon-formably on both the Carolina Slate Belt and the Triassic Deep River basin. This member is best exposed in the southeastern part of the county, where overlying younger sediments have been strip-ped away by erosion. It is rarely exposed in the south-central and southwestern parts of the county, where it usually is covered by overlying sediments. The base of the lower member is exposed in a road cut on the west side of Highway U.S. 15-501 on the south side of Little River. At this locality it is underlain by the Triassic Sanford formation. The basal part of the member is a grey carbonaceous clay containing lignitized wood. The section at this exposure is as follows : Section near juunction of Highway 15-501 and Little Rixer Top of section covered Cretaceous (Tuscaloosa formation member) Thickness 6. Weathered reddish brown clay.— 3' 5. Dark grey plastic carbonaceous clay 3' 4. Fine greyish green sand : 1' 3. Dark grey plastic carbonaceous clay, containing liginitized wood 4' 2. Basal gravel _ '. 6' Unconformity Triassic (Sanford formation) 1. Fanglomerate 3' Base of exposure The gray carbonaceous clay of the basal part of the lower member is again exposed in the west bank of a paved road on the south side of Nicks Creek, approximately one mile north of Murdocksville. This locality contains both wood fragments and amber. The type locality of the lower member of the Tus-caloosa formation is an exposure along the Seaboard Air Line Railroad in the center of the town of Vass. The section at this locality is as follows : Section at Vass Recent Thickness 7. Soil zone, weathered and leached, being colored sand with occasional gravel beds 6' Cretaceous (Tuscaloosa formation lower member) 6. Oxidized, mottled light olive and red clay 4' 5. Oxidized, iron cemented, greyish-olive sandstone 1' 4. Oxidized, light olive silty clay 8' 3. Oxidized, feldspathic, micaceous clayey course olive sand, with occasional gravel beds stained by hematite 6' 2. Oxidized, micaceous olive clay, containing some silt and sand 3' 1. Unoxidized, micaceous, light grass green sandy clay.. 6' Base of exposure A water well, located approximately one-fourth of a mile northwest of the type locality, drilled for the town of Vass by C. C. Hildebrand and Company, record the following section : Log of Water Well at Vass Thickness 8. White and yellow sand 4' 7. Yellow sand clay 16' 6. Light yellow and light grey sand clay.. 5' 5. Light grey sandy clay - 10' 4. Light brown sandy clay 10' 3. Water bearing sand - 35' 2. Light brown sand clay 15' 1. Basement rocks of the Carolina Slate Belt 364' An exposure southeast of Lobelia on the south bank of Little River at Morrison, Bridge, Hoke County, is as follows : 14 Section along Little River at Morrison Bridge Cretaceous (Tuscaloosa formation, lower member) 2. Festooned cross-bedded micaceous, feldspathic, grey-ish white and light grey, poorly consolidated sand, containing lignitized logs, grey clay balls, and heavy mineral streaks. (These streaks are composed of as much as 50 percent pyrope garnet. The lignitized logs are partly replaced by plastic grey clay in which growth rings are preserved) 5' 1. Unoxidized light grass green, micaceous, sandy clay 1' River level Two exposures of well cemented coarse sandstone occur in the county. One is located northwest of Taylor Town on the north bank of Joes Fork Creek, and the other on the north shore of a private lake, just above Hog Island intersection. Judging from the elevation of the exposure, neither of these out-crops could be far above the base of the unit. The two sandstones are identical in appearance and, if they could be correlated, might be of stratigraphic significance. These sections are as follows : Section along Joes Fork Oreek northwest of Taylor Town Cretacious (Tuscaloosa formation, lower member) Thickness 3. Oxidized reddish brown clay 3' 2. Coarse grained, well cemented greyish brown sandstone 2' 1. Oxidized light grey clay. 2' Base of exposure Section: at Hog Island Cretaceous (Tuscaloosa formation, upper member) Thickness 5. Basal quartz gravel 2' Unconformity (Tuscaloosa formation, lower member) 4. Dark grey clay mottled with secondary hematite____ 1.5' 3. Dark grey clay 3.5' 2. Coarse to medium grained, well cemented greyish brown sandstone 2' 1. Dark grey silty clay ...„ 3' Base of section A complete stratigraphic section of the lower mem-ber of the Tuscaloosa formation in Moore County is not available, but from what is known, it can be stated that the basal part consists of grey carbonace-ous clays containing lignitized plant remains and amber, with interbedded thin, grey and olive sand beds. Above the base, the clays become less carbon-aceous and lighter grey in color ; finally giving way to light olive clayey sand beds containing thin clay beds. Some of the sands exhibit faint graded bed-ding and cross bedding. Although a few of the clay beds are lenticular in outline, most persist over the exposed outcrop area. In the subsurface some beds can be correlated on electric logs traced over wide areas (P. M. Brown, personal communication). Upper- Member: The upper member of the Tusca-loosa formation unconformably overlaps the lower member as well as segments of the Carolina Slate Belt and Deep River basin. The outer limits of the upper member is an irregular contact which can be traced in a northeast-southwest direction across the county. Typical exposures are found in the area around Harris Crossroads; however, measure sec-tions in this unit are of questionable value because of the extreme variable nature of the sediments. For this reason, a type section of the upper member of the Tuscaloosa formation has not been established. The base of the upper member is exposed at a number of localities along the margin of the Coastal Plain. It is an unconsolidated gravel composed of rounded quartz, varying from one to six inches in diameter. These gravels were probably derived from quartz veins in the Carolina Slate Belt. This basal gravel is thin, usually not over six feet thick, and in some places is totally absent. The basal gravels become finer grained and diminish in thick-ness to the southeast and might completely disappear down dip. The gravels have a bleached appearance, and might have been subjected to intensive weather-ing, which removed iron staining, before transporta-tion. Though some of the cobbles show faint pink staining, the absence of iron contrasts with both vein quartz in the Carolina Slate Belt and Recent terrace deposits. The matrix of the basal gravel is composed of kaolinitic clay and clayey sand. Small quantities of heavy minerals are interspersed through the matrix. Above the basal gravel, the upper member of the Tuscaloosa formation consists of alternating uncon-solidated beds of white clay and clayey sand. The clay beds pinch and swell and sometimes die out. These beds are composed of white plastic kaolinite, which, if weathered, is often stained pink by iron oxide. Quartz grains up to one millimeter in diam-eter are randomly scattered throughout the clays, and sometimes make up as much as five percent of the deposit. These quartz grains are usually very angular, almost glass clear, and show little or no rounding and frosting. In addition to the quartz, the clays also contain mica shards. The sand beds usually are more persistent than the clay beds, although they also tend to thicken, thin and occasionally pinch out. Most of the sand beds are relatively massive and are only faintly bedded. Some are crossbedded and others exhibit graded bed-ding. A few of these deposits contain occasional fine gravel interbeds. Kaolinitic clay galls, varying from one-half to one and one-half inches in diameter, occur sparingly in the gravel beds and along promi- 15 nent bedding planes. The sands are composed of medium to coarse, sub-rounded quartz grains with mica shards, feldspar grains, and rare heavy min-eral streaks along bedding planes. The sands are bonded together by kaolinitic clay. This clay, which is always present, at times makes up as much as twenty-five percent of the sediment. Thin beds of hematite up to one inch thick occur as a precipitate from groundwater on the upper sur-faces of many of the clay beds and along prominent bedding planes in the sand beds. Hematite and occasionally limonite precipitates, have oftentimes cemented the base of the upper mem-ber of the Tuscaloosa formation. These deposits are as much as six inches thick. Environment of Deposition : The lower member of the Tuscaloosa formation was probably deposited in a marine environment. Although marine fossils are lacking in Moore County, they have been recover-ed from well cuttings down dip (P. M. Brown, per-sonal communication). The persistence of the beds and general rarity of cross bedding suggest these sediments were laid down under marine conditions. The gradual change from grey carbonaceous clays at the base to green and olive clayey sands and thin grass green clay beds above the base, probably rep-resents a change from lagoonal, with stagnant con-ditions, to marine environment, brought about by transgression of the Lower Tuscaloosa sea. Other evidence for the marine origin of the lower member of the Tuscaloosa formation is suggested by Heron's (1960) study of exposed basal Cretaceous clays of North and South Carolina. He found that known marine sediments contain abundant montmo-rillinite, whereas sediments regarded as non-marine contain kaolinite. He found that the Cape Fear formation (lower member, Tuscaloosa formation) contained predominately montmorillinite with some kaolinite, suggesting that it is a marine sediment. The samples collected from the lower member of the Tuscaloosa formation of Moore County were X-ray analyzed by Heron at the request of the author. These were found to contain a majority of montmorillinite over kaolinite (S. D. Heron, writ-ten communications). Although montmorillinite as an indicator of marine origin is still open to question by some authors ; the present investigation suggests that it is applicable in this case. The environment of deposition for the upper mem-ber of the Tuscaloosa formation has been discussed in the literature. L. W. Stephenson (1923) believed the Patuxent formation to be of alluvial origin, deposited by overloaded streams crossing the Coastal Plain of that period, which existed between the coast line to the east and the highlands to the west. Veatch (1908) stated that the almost pure kaolin-ite beds in the Tuscaloosa formation were clearly of sedimentary origin. He postulated that these sedi-ments were derived from deeply-weathered crystal-line rocks of the Piedmont in which the feldspar and other aluminus minerals had altered to kaolinite. During Cretaceous time, these weathered rocks were rapidly eroded and deposited along the sea as alluvial fans and at the mouths of streams as deltas. On these deltas fresh water lakes were formed and filled with reworked kaolinite clay. As these lakes were filled, others formed. Newman (1927) agreed that the clays were de-rived from weathered rocks of the Piedmont, but postulated that they were leached to essentially pure kaolin in situ in pre-Cambrian time, under the in-fluence of mild climate with heavy rainfall, aided by acid conditions created by decaying vegetation. This weathered material was then eroded, transported by streams, and deposited in a marine environment. Kesler (1957) agreed with Veatch's deltaic origin, but added that the sediments were derived from a youthful erosion surface. He postulated that the kaolins were formed by weathering of feldspars after deposition of the sediments, and were concen-trated by later reworking. Heron (1960) stated "The sediments of the Mid-dendorf formation (upper member Tuscaloosa formation) probably represent an environment that was dominately fluvial". He suggested that the rela-tively pure clay bodies, having the shape of small basins, may represent deposition in a floodplain, such as the filling of an abandoned meander. The upper member of the Tuscaloosa formation in Moore County is considered unfossiliferous although is contains marine fossils down dip (P. M. Brown, personal communication) . This fact has led to the development of various theories about its environ-ment of deposition of which too little attention has been paid the source of the sedimentary kaolin beds in the updip facies of the upper member. In regard to this fact, a residual clay is developed on Carolina Slate belt rocks directly underlying the upper member. It is felt that this residual clay is indicative of the source of the sedimentary clay in the upper member of the Tuscaloosa formation. If the crystalline rocks of the southeast were blanketed prior to Upper Tuscaloosa time, by residual kaolins, which were eroded and deposited during Upper Tus-caloosa time, this would explain the widespread oc-currence of sedimentary kaolins in the upper mem-ber of the Tuscaloosa formation. 16 Norlh Carolina State Library Raleigh The McKennis pit (see Plate 1, for location) is a typical residual kaolin deposit. The stratigraphic section exposed in this pit is as follows : Section of McKennis Clay Pit Recent Thickness 5. Present day soil zone which extends down from the surface into unweathered gravel 4' Tertiary (Pinehurst formation) 4. Gravel ._: 1' Unconformity Cretaceous (Tuscaloosa formation, upper member) 3. Pink and white mottled clayey sand 3' 2. Basal gravel _._ 1' 1. Kaolinitic clay containing quartz veins, still pre-serving the fine alternating graded bedding of the slates. (The relic bedding strikes north 45 degrees east and dips southeast at 30 degrees) 2' Base of section This locality was visited by Mr. E. F. Goldston, North Carolina State College, Department of Soils, at the request of the author. At the time of exami-nation, Mr. Goldston stated the following about the deposit : 1. The Coastal Plain is too thick for the kaolin to have been formed in place by weathering after depo-sition of the Upper Tuscaloosa member and overly-ing sediments. 2. A climate capable of producing this degree of weathering and leaching would, of necessity, have been warmer and had more rainfall than present. A section exposed on the north bank of Little River, where the Murdocksville road crosses the river, is as follows : Section of Little River Thickness Cretaceous (Tuscaloosa formation, upper member) 4. Sandy clay 8' 3. Basal gravel composed of quartz pebbles, ranging in diameter from 1 to 6 inches, in a mtarix of kaolinitic sand 2' 6" Triassic (Sanford formation) . 2. Sandy kaolinitic clay, developed on the Sanford formation grading downward into unweathered red sandstone 3' 6" 1. Red sandstone 2' Base of section This section indicates that Triassic rocks as well as the Carolina Slate Belt were highly weathered and leached prior to deposition of the upper member of the Tuscaloosa formation. Occurrences of residual kaolin underlying the Tus-caloosa formation in Georgia suggest that the pre- Upper Tuscaloosa mantle was an extensive deposit because Munyan (1938) states, "Recently the writer, while mapping Cretaceous rocks (in Georgia) saw a number of contacts between the Tuscaloosa and the underlying crystalline rocks. The crystalline rocks were weathered to primary kaolin in many instances and could be identified as crystallines only by the presence of thin, but continuous quartz veins. The overlying rock could easily be identified as unaltered sediment. In no case observed did it appear that the weathering of the underlying crystalline rocks was due to leaching after the deposition of the sediment". From this evidence it is postulated that in pre- Upper Tuscaloosa time the Carolina Slate Belt and the Deep River Triassic basin were peneplained and subjected to intensive weathering and leaching un-der tropical conditions, producing a thick residual kaolinitic mantel. In order to prevent the mantel from being eroded away as fast as formed, the area was, of necessity, relatively flat. If a transgressing sea slowly inundated this peneplaned surface, it would be expected that the upper member of the Tuscaloosa formation would have been laid down in a shallow environmental basin under near shore con-ditions. Streams emptying into this basin during flood stage, would bring in sediments ranging in sizes from clay to gravel. As the flood subsided the sediments would become finer grained, explaining why some of the sediments contained graded bed-ding. Cross bedding would be expected in such an environment. During times when the streams were not in flood stage, they would be carrying colloidal clay, which on entering the basin would slowly settle out as a thick viscous mass. The surface of the basin floor was probably irregular with more clay accumulating in the depressions than elsewhere. This explains why the clay beds pinch and swell. The next flood would bring in another slurry of coarse sediments which would be deposited on top of the clay beds. The colloidal clays would then act as highly viscous media allowing some of the sand grains from the overlying sediments to settle into the clay, while supporting the remainder. This ex-plains the presence of sand grains in otherwise pure kaolinitic clay. The coarse basal gravel of the upper member of the Tuscaloosa formation was probably derived from quartz veins which intruded the Carolina Slate Belt. The quartz could have been brought in by streams, however, it has been noted, in many places in Moore County, underlain by rocks of the Carolina Slate Belt, that the surface of the ground is covered by a lag pavement of vein quartz. If areas covered by these lag gravels were exposed to wave action of an advancing sea, this action could rapidly produce 17 a deposit similar to the basal conglomerate of the Upper Tuscaloosa member. As previously noted, the basal gravel is thin, variable in thickness, and in places totally absent. Pettijohn (1957, p. 244) states "blanket conglomerates . . . were deposits of gravel spread out by an advancing or transgressive beach. These deposits are notably thin and patchey; low areas may collect several tens of feet of gravel whereas the intervening high areas may be devoid of any gravel accumulation". the upper member of the Tuscaloosa formation. This contact is an undulating line, indicating a rough erosional surface developed on the upper member of the Tuscaloosa formation before deposition of the Pinehurst formation. This contact can be recog-nized at numerous localities in the county ; one of the better of these is exposed in the west bank of high-way U.S. 15-501 at the Vass road overpass, approxi-mately one and one-half miles southeast of Carthage. This section is as follows : TERTIARY PINEHURST FORMATION m Gravel beds overly the upper member of the Tus-caloosa formation in Moore County. The gravel deposits near Lakeview were described by Stephen-son (1912) and correlated with the Lafayette forma-tion of Pliocene age. Bryson (1930) described a number of gravel pits in Moore County and stated that the exposures are of one group and probably belong to the Lafayette formation. In the Halifax area, Mundorf (1946) recognized graven deposits which he called unclassified high level gravel. He postulated they were probably of differing ages ranging from Cretaceous to Tertiary. Richards (1950) recognized high level gravels in Moore County, but did not attempt to define the distribu-tion or suggest the age. Reinemund (1955) mapped high level gravels in Moore County and stated that they covered almost a fifth of the area shown in his geologic map. He considered all of the Coastal Plain deposits high level gravel, not recognizing the upper member of the Tuscaloosa formation which directly underlies the gravel throughout the county. The gravels are unfossiliferous and the exact age is not known. In the northeastern part of the State, similar deposits unconformably overlie the late Mio-cene Yorktown formation (P. M. Brown, personal communication). Although regarded as Pliocene age by Stephens et. al. it is conceivable that these surficial gravels could be Late Miocene, Pliocene, or Early Pleistocene age. Stratigraphy: During this investigation it was found that the so-called high-level gravels could be recognized and mapped as a stratigraphic unit in areas covered by Coastal Plain sediments. It is therefore proposed that this unit be called the Pine-hurst formation after the town of Pinehurst which is underlain by these sediments. The type section for the formation is located in the D. H. Wilson sand pit on the north side of Highway 211, approximately one and one-half miles southeast of the center of the town of West End. The Pinehurst formation unconformably overlies Section along Highway 15-501 at Vass Overpass Tertiary (?) (Pinehurst formation) Thickness 2. Brown limonite stained, faintly bedded, coarse sand; containing lenses of well rounded quartz gravel, ranging in size from one-half to two inches with interspersed kaolinitic clay balls 10' Unconformity Cretaceous (Tuscaloosa formation, upper member) 1. White kaolinitic clay, pink mottled at the top 2' In Moore County the Pinehurst formation is a nonfossiliferous sand and gravel which caps all of the higher Coastal Plain hills in central and western Moore County. It has not been observed resting directly on sediments older than the Upper Tusca-loosa. The Pinehurst formation is exposed on top of the high hill at Carthage, at an elevation of over 500 feet. From this elevation it slopes to the southeast, at first steeply, becoming more gentle down dip until it reaches an elevation of about 350 feet in the southern part of the county. The gravels on the hill at Carthage range in thick-ness from 3 to 7 feet and consist of a coarse-brown, iron-stained sand containing lenses of quartz peb-bles, ranging in diameter from 2 to 5 inches. Down dip the formation gradually thickens until, in the southern part of the county, it is over 150 feet thick. Bedding and composition rapidly change from coarse sands, containing pebble beds and lenses, at Car-thage to festooned cross-bedded sands and fine grav-els down dip. The formation usually is brown or greyish brown in color. It is often iron stained, and sometimes cemented with either hematite or limonite, hematite being the more common. Hematite concretions occur within the formation. The outside of these struc-tures are coated with sand grains. Although they are usually oval or spherical in outline, some have a stair step appearance from preservation of relic bending planes. When broken they are oftentimes hollow and contain hematite powder which local folklore attributes as the source of red Indian war paint. Sometimes this hematite occurs in lumps 18 and when a concentration is shaken emits a sound, from the hematite hitting the walls of the structure ; thus giving rise to the common name "rattle rock". Hematite and occasionally limonite is precipitated at the base of the formation in deposits varying from a few inches to over a foot in thickness. Kaolinitic clay balls are commonly interspersed throughout the formation. They usually occur along prominent bedding planes and in gravel beds. Heavy minerals are much more common in this formation than in the underlying Tuscaloosa, which is relatively devoid of heavy minerals. They are concentrated along bedding planes and are rarely dispersed through the sediment. The upper surface of these deposits is covered by olive-brown silt and fine sand ranging in thickness from one to five feet. These deposits are attributed to wind action in the form of winnowing. The process was probably aided in the recent past by denudation of the area by forest fires, but is still going on today as can be attested to by observing sparsely vegetated areas on a windy day. The Pleasant sand pits, between Pinehurst and Aberdeen, contain sediments dissimilar to the other parts of the Pinehurst formation. These deposits consist of water laid, well-sorted, thin-bedded, fine white sands; thin, fissle-bedded, grey silts and plastic clays ; and occasional micro-cross bedded fine sands. These deposits are covered by approximate-ly four feet of wind blown silt and fine sand. Because of the thinness of the Pinehurst forma-tion, the major streams have cut the deposit leaving it capping hills along stream divides and draping down the hillsides. These sand and gravel capped hills are commonly referred to as the "Sand Hills Region". Many times the tops of the hills are con-cordant, flat, and slope gradually to the southeast. These might represent preservation of original con-structional topography. Environment of Deposition: Lithology and ab-sence of fossils suggest the Pinehurst formation is nonmarine. However, it could have, in part, been deposited in a transition zone. In such a zone con-ditions for preservation of fossils are poor; and, if preserved, they could have been subsequently leach-ed away. The sediments were derived from a nearby source and carried by vigorous streams in a youthful stage of development, as indicated by the beds and lenses of coarse gravels in the coarse sands around Car-thage. A change of environment from stream to deltaic is indicated by comparing these deposits with the cross bedded, finer grained sands and gravels down dip. This change is further suggested by the gradient of the formation which is steepest at Car-thage, becoming rapidly less steep, almost flat, down dip. The beds of coarse gravel at Carthage and change in gradient down dip also indicates that one of the major streams emptying into the basin of deposition was located in the general vicinity of Carthage. As sedimentation progressed, deltas grew outward from the mouths of streams emptying into the basin, explaining why the formation thickens down dip. An interesting feature of the Pinehurst formation is the presence of kaolinitic clay galls. Although clay galls were occasionally observed in Upper Tus-caloosa outcrops, they are universally present in the Pinehurst formation. Whether the kaolinite was derived from erosional outliers of the underlying Tuscaloosa formation or from weathered Carolina Slate Belt rocks is open to debate. PettiJohn (1949) attributes the formation of clay galls to the dessica-tion and breaking up of mud cracks. Mud cracks could have easily formed on mud flats along deltaic distributaries and been incorporated in the sedi-ments when these mud flats were inundated during flooding. The final product of sedimentation was a series of coalescing deltas, creating a blanket deposit of cross bedded unconsolidated sand and gravel. The fine sands and clays exposed in the Pleasant sand pits were probably deposited in a small fresh water lake, created by blocking of one of the distributaries. Post depositional wind action in the form of win-nowing produced the fine sands and silts which cover the Pinehurst formation in many places. Structure: The Coastal Plain sediments dip to the southeast at six to eight feet per mile. This angle of dip is somewhat steeper than the average for the Coastal Plain, but these are deposits along the ancient coastal margines and should dip more steeply. No faulting has been observed in Coastal Plain sediments even though slicken-sides were ob-served in Upper Tuscaloosa clays in a borrow pit on the west side of Highway U.S. 1, at the southern city limits of Aberdeen. Erosional unconformities occur at the base of the lower member of the Tuscaloosa formation and at the base of the Pinehurst formation. The existence of an unconformity at the base of the upper member of the Tuscaloosa formation is suggested by the pres-ence of what appears to be a weathered zone develop-ed on top of the underlying lower member. A basal conglomerate in the upper member also suggests a break in the sedimentation cycle. 19 I Other Deposits Terrace Gravels: Although Reinemund (1955) mapped four levels of terrace gravels, this author only recognized and mapped three levels in Moore County. The lowest of the terraces (Terrace No. 1, Plate I) is found as scattered remnants along Aber-deen Creek, Little River, and Crane Creek. Sedi-ments underlying this terrace level consists of iso-lated patches of sand and gravel at elevations from ten to fifteen feet higher than present floodplains. It is light tan-colored coarse sand and well rounded gravel. The gravel fraction is composed predomi-nately of quartz with some Carolina Slate Belt frag-ments. The gravel is somewhat variable in size, ranging in diameter from 1 to 3 inches. The most extensive of the terrace deposits (Ter-race No. 2, Plate I) occurs from 20 to 30 feet above present floodplains. It is the only terrace level which has developed to any extent on the crystalline rocks of the Carolina Slate Belt. This level occurs along Cabin Creek, north of Robbins, and along the length of Deep River. The terrace deposits consist of yellow-brown fine sands and clayey sand with occasional interbedded silts and fine gravel. The gravels are one-quarter to one-half of an inch in diameter with some ranging upward to over one inch. These deposits are usually covered by 12 to 18 inches of coarse silt and fine sand. The highest of the stream terraces (Terrace No. 3, Plate I) , occurs at elevations of 65 to 70 feet above present floodplains. It is only found along Deep River east of Glendon and Little River north of Mt. Pleasant. Terrace deposits underlying this level are composed almost entirely of gravel with sand and clay filling the interstices. Rare thin interbeds of silty clay are present in the deposit. The subangular to rounded gravels are composed of approximately 70 per cent quartz and 30 percent Carolina Slate Belt rocks. The sand fraction is composed mainly of coarse, angular, quartz grains with occasional feldspar grains. Soils developed on these deposits have a distinc-tive red color. The "B" soil horizon is a maroonish-red sand loam, whereas, the "A" horizon is a red-dish- brown silty loam. The three levels of river terraces indicate three periods of downcutting and stream aggradation, followed by deposition of alluvial sediments in the valleys. Therefore, the highest of these deposits is the oldest ; the lowest is the youngest with each suc-cessive period of cutting lowering the stream and bringing it closer to the present base level. The periods of aggradation were probably caused by a drop in a sealevel ; the subsequent deposition by ris-ing sealevel. The river terrace deposits in North Carolina have been regarded in the literature as Pleistocene age. Successive sets of terraces were supposedly formed due to alternating glaciation and melting producing a rise and fall in sealevel. The terraces in Moore County do not contain fossils and have not been traced into known Pleistocene deposits; therefore, their age determination is left to conjecture. Alluvium: The alluvium filling present stream valleys consists predominately of chocolate-brown and greyish-brown silt with some light and lark grey organic clays. It is conspicuously absent in those parts of the county underlain by the Carolina Slate Belt. However, it is usually present along streams flowing over much of the Triassic basin and Coastal Plain. The presence or absence of alluvium is determined by the relative resistance to erosion or the rocks underlying the streams. ECONOMIC GEOLOGY Pyrophyllite Pyrophyllite is a hydrous alminum silicate classi-fied as a high alumina mineral. Its formula is Al2 3 .4 Si0o.Ho and consists of 66.7 percent Si02 , 28.3 percent A12 3 and 5.6 percent H20. It is used in the manufacture of ceramics, paint, rubber, insecticides, roofing, and paper. Its major produc-tion goes into ceramic products and mineral filler. Moore County contains the largest pyrophyllite ore reserves in the United States. This mineral has been mined near Glendon for over a hundred years. The pyrophyllite at Glendon was originally thought to be talc, until Emmons (1856) reported that it contained aluminum. He called it agalman-tolite, a soft material consisting chiefly of pyro-phyllite used in the Orient for making carvings. In addition he described the quarry at Hancock's Mill (Glendon) at some length. Brush (1862) analyz-ed material from Hancock's Mill and concluded that it was pyrophyllite. Pratt (1900) discussed the occurrence of pyrophyllite at Glendon and described Phillips, Womble, Rogers Creek, and other deposits. He noted that the pyrophyllite was often silicified and occurred in iron breccia which merges into pyro-phyllite schist. Stuckey (1928) investigated the pyrophyllite deposits of Moore County and discussed their location, size, mode of occurrence, origin, and economic possibilities. Pyrophyllite Mines and Prospects Pyrophyllite deposits occur in four areas in Moore County ; namely, north of Glendon, southeast of Hal- 20 lison, southwest of Robbins, and on Cabin Creek near the Montgomery-Moore county line. Eight pyrophyllite mines and prospects are located on the Glendon fault from McConnell northeast to the county line. This area contains the largest number of deposits in the county. Two pyrophyllite mines are located on the Robbins fault, south of Robbins. Both of these deposits are at present being mined. McConnell Prospect : The McConnell prospect lies approximately 0.5 of a mile northeast of the village of McConnell. The pits are now grown over, but the dumps contain sericite schist and foliated pyrophyl-lite. Highly sheared sericitized felsic tuff, in part silicified, is exposed along an access road, west of the prospect. Exposures available at the time of investigation indicate the shear zone of the Glendon fault in this area is only about forty feet wide and the mineralized zone approximately ten feet wide. Jackson Prospect: The Jackson prospect lies on the south side of Deep River approximately three miles northeast of the McConnell prospect. The shear zone of the Glendon fault in this area is about 200 feet wide. The deposit is located on the fault contact between andesitic tuff to the northwest and slates to the southeast. Two prospect pits have been put down to a depth of about 8 feet. They expose white foliated sericite ; however, no pyrophyllite was observed. Bates Mine: The Bates mine is located on the northeast bank of Deep River approximately two miles northeast of the Jackson prospect. Stuckey (1928) stated that this mine was prospected in 1903 and a mill constructed in 1904. The mine was op-erated until 1919 at which time it closed due to lack of quality ore. The rock is sheared and mineralized in a zone 150 feet wide, along the Glendon fault. The hanging wall to the northwest is composed of andesite tuff; the footwall to the southeast is composed of slate. The pyrophyllite is developed in a band, about three feet wide in the area of major displacement of the fault zone and grades into sericite schist on either side. The ore zone strikes north 70 degrees east and dips northwest at 80 degrees. Phillips and Womble Mines: The Phillips and Womble mines are separated from each other by the Siler City-Glendon road, and lie approximately two miles northwest of Glendon. These mines were map-ped by plane table and alidade at a scale of one inch equals 50 feet (see Plate 2) during the field investi-gation for this report. The Glendon fault is exposed for approximately 1800 feet along strike in active and abandoned mine workings. The ore body lies in the shear zone of the fault and dips to the northwest at an average angle of 65 degrees. The ore body is lenticular in outline and pinches and swells, but is considerably less in the pinches. Pyrophyllite has also been developed along minor displacements parallel to the main fault. White Mine : The White Mine is located on Rogers Creek approximately 0.8 of a mile northeast of the Womble mine. The ore body is contained between the Glendon fault on the southeast and a secondary reverse fault on the northwest. The ore body is lenticular in outline and dips to the northwest at an angle of 60 degrees. It is exposed along strike in the pit for 375 feet. Recent investigation indicates that the ore body continues to the southwest for a considerable distance. To the northeast it is not traceable beyond the mine. An exposure along the southwest wall of the pit reveals relatively unaltered rock overthrusting the ore body. The direction of movement along this fault was toward the southeast, indicating that the ore body might be overthrust to the northeast. The country rock surrounding the deposit is interbedded slate and andesitic lithic tuff and is stratigraphically in the gradational contact zone between the andesitic tuff and slate units. The contact between mineralized rock and unaltered rock is unusually sharp being gradational for only a few inches or at the most a few feet. Jones Prospect : The Jones prospect lies approxi-mately one and four tenths miles northeast of the White mine. Surface exposures indicate that the rock in this area is highly sheared. Prospect pits reveal foliated pyrophyllite and masses of sericite schist containing chloritoid. The general size of the deposit could not be discerned. As Stuckey (1928) pointed out, the pyrophyllite is considerably iron stained. This staining is probably caused by weathering of chloritoid and might not persist with depth. Currie Prospect: The Currie prospect is located almost on the northern county line, one mile east of the Jones prospect. This prospect lies east of the Glendon fault. The rock in this area is slate, in places, sheared to a sericite schist. Although Stuckey (1928) reported pyrophyllite occurred at this deposit, none could be found during this investi-gation. The old prospect pits are covered with over-growth and reveal little about the deposit. Standard Mineral Company Mine : The Standard Mineral Company mine is situated two and one-fourth miles southwest of Robbins. This deposit was 21 discovered in 1918, by Mr. Paul Gerhart, and min-ing commenced soon thereafter. This operation is the only pyrophyllite mine in the state worked under-ground. Ore is at present being removed from the eighth level, about 400 feet below the surface. The pyrophyllite zone is exposed in the mine pit for over 1300 feet continuing beyond the area map-ped (see Plate 3). The ore body dips northwest at 50 degrees to 70 degrees and lies in a zone of compli-cated reverse faulting. In places this faulting has repeated the pyrophyllite zone, making the mine-able ore body as much as 150 feet wide. The north-eastern half of the deposit is offset to the northwest by cross faulting. The ore body is surrounded by slate which has been sericitized for as much as 300 to 400 feet on either side of the deposit. Dry Creek Mine : The Dry Creek mine is located along the strike of the Robbins fault and lies two miles southwest of the Standard Mineral Company mine. The ore is exposed in two pits located 500 feet apart. It has developed along two thin parallel shear zones (see Plate 5). Ore bodies exposed in the southern pit lie to the northwest of the strike of the northern pit, indicating that the mineralized zone is offset by cross faults. The ore bodies pinch and swell along the strike of the faults, and rarely exceed 20 feet in width. The county rock is highly sericitized slate. Ruff Mine : The Ruff mine is located one and one-half miles southwest of Hallison. The ore body can be traced for over 180 feet. It occurs in a fault zone which strikes north 20 degrees east and dips north-west at 80 degrees. The southeastern limb of the ore body is displaced to the northwest by a cross fault which strikes north 45 degrees west and dips to the northeast at 75 degrees. The mineralized zone averages from 6 to 15 feet wide in the center, but narrows to the northwest and southeast, finally dying out along strike in these directions. The coun-try rock is an andesitic lithic tuff. Hallison Prospect : Pyrophyllite was discovered six tenths of a mile west of Hallison during the re-opening of an old gold mine (Stuckey 1928). At this locality several shallow pits have been dug along a quartz vein. The rock in contact with the quartz is a sericite schist containing a minor amount of pyrophyllite. The prospect is located in the shear zone of a north 70 degrees east trending fault, dip-ping northwest at 55 degrees. This fault forms the contact between felsic tuffs and slates. If any de-gree of mineralization took place in the slates along this fault there is a possibility of the existence of a workable deposit in the area. Sanders Prospect : The Sanders prospect is locat-ed on a hill northwest of the intersection of Cotton Creek and Cabin Creek. The top of this hill has recently been bulldozed along strike of the deposit for approximately 250 feet. This cut exposes seri-citized slate which becomes sericite schist near the zone of maximum shear of a north 35 degrees east trending fault, dipping 70 degrees northwest. Seri-cite developed along this fault can be traced from Cotton Creek northeastward for about 1000 feet. Quartz veins have been emplaced in the center of this fault zone. Pyrophyllite is developed adjacent to the quartz veins, and where it occurs in direct contact with the veins, forms radiating rosettes. The pyrophyllite zone rarely exceeds three feet in width. Weathered pyrophyllite outcrops are highly iron stained; unweathered pyrophyllite is relatively free from staining but contains excessive chloritoid. Origin of Pyrophyllite The pyrophyllite deposits of Newfoundland (Bud-dington, 1919), North Carolina (Stuckey, 1928) and California (Jahns and Lance, 1950) all occur in rocks of volcanic origin. Buddington (1919), Stuck-ey (1928), Vhay (1937), Jahns and Lance (1950), and Broadhurst and Council (1953) have all regard-ed the origin of pyrophyllite as hydrothermal re-placement. Hurst (1959) from a study of the mineralogy of Graves Mountain, Georgia believed that kyanite in the deposit formed under water deficient conditions at high temperature and pressure. The pyrophyllite is thought to have formed by the ingress of water along fractures partially converting kyanite to pyro-phyllite. Zen (1961) from a study of samples collected from various pyrophyllite deposits of North Carolina tended to disregard the effect of hydrothermal re-placement solutions on the formation of the pyro-phyllite bodies. The presence of three phase min-eral assemblage of the ternary system A12 3-H2 0- SiO.„ in his estimation, indicated water acted as a fixed component. However, he further noted that to say water acted as a fixed component did not com-pletely imply the absence of a free solution phase (hydrothermal solutions), such a phase could have existed, but certainly did not circulate freely through the system destroying the buffering mineral assem-blages. From a study of the occurrence of pyrophyllite in Moore County, certain similarities among the dif-ferent deposits became readily apparent. These de-posits are selective to rock type, occur in shear zones 22 of major longitudinal faults, are lenticular in out-line, have similar mineralogies, and are zoned. Rock Types: The major pyrophyllite deposits in the county occur in the slate unit. The wall rock in the White mine consists of alternating beds of slate and andesitic tuff, whereas the wall rock of the Ruff mine is composed entirely of andesitic tuff. It is interesting to note that both these rocks are com-posed of easily sheared water laid, volcanic sedi-ments. No pyrophyllite deposits have been observed in either felsic tuffs or mafic tuffs. This is not meant to imply that pyrophyllite does not occur in these rocks, because it is reported in altered rhyolites in Newfoundland (Vhay, 1937), and in felsic tuffs in North Carolina (Stuckey, 1928) ; and Broadhurst and Council, (1953). On the other hand, the ability of the slates and andesitic tuffs to readily shear and develop schistosity must have been a factor in the formation of pyrophyllite. Faults : Stuckey (1928) recognized that the pyro-phyllite deposits of Moore County occurred in shear zones. During this investigation it was found that the pyrophyllite deposits north of Glendon and southwest of Robbins occur in the shear zones of the Glendon and Robbins faults. Although not studied in as much detail, the Sanders and Ruff deposits also occur in fault zones. Some of the pyrophyllite pits contain as many as four parallel northeast trending faults. The ore bodies in the White, Standard Mineral Company, and Dry Creek mines have all been offset by cross faults. Pyrophyllite has not developed along these cross faults indicating that they developed after pyrophyl-litization. Low angle thrust faults were observed in the hanging wall of the Womble and White pits. Cross faults in the White pit do not offset the thrust sheet, indicating that thrusting occurred after cross fault-ing. Outline of Pyrophyllite Bodies : In 1928 Stuckey noted that the pyrophillite bodies were lenticular in outline. This investigation revealed that the ore bodies pinch and swell along their whole length eventually dying out along strike. It also revealed that the bodies all trend northeast and pitch north-west, their development being controlled by major northeast trending, northwest dipping longitudinal faults. Subsurface information made available dur-ing this investigation indicates that the ore bodies not only pinch and swell along strike, but down dip as well. Mineralogy : The pyrophyllite deposits all contain the mineral pyrophyllite, sericite, kaolinite, quartz, hematite, and chloritoid. In addition, the fault zone at the Phillips, Womble and Snow properties contain small augen masses composed of pyrophyllite, topaz and diaspore. A sample of this material was col-lected at the Phillips property. Eldon P. Allen, a staff member of the Division of Mineral Resources, calculated percentages of each mineral present, using microscopic techniques, as follows : 27 percent pyro-phyllite, 36 percent diaspore, 37 percent topaz, and 1 percent fluorite. Diaspore has also been reported at the Sanders property (Stuckey, personal com-munication). The only crystalline radiating phyrophyllite ob-served was in contact with vein quartz at the Sanders Property. Fluorite crystals occur in the vein quartz intruding the fault zone at the Phillips Property. Pyrite cubes and chlorite masses are found in the sericitized wall rock at this site. The pyrite cubes are invariably coated by a tissue thin film of quartz, even though the host rock is not silicified. The pyrite cubes on the hanging wall side of this deposit have a rhombic dodechedral face which is absent in the cubic crystals of the footwall. Silicification is prevalent at the Phillips, Wom-ble, Snow, Dry Creek, and Standard Mineral Com-pany mines. Solutions which brought in this silica in places also introduced copper and gold. Silicified rock in the hanging wall of the Womble pit is stained with azurite and malachite. Silicified rock in the hanging wall of the Standard Mineral Com-pany's pit contains gold which was mined before pyrophyllite was discovered. Zoning : Each of the pyrophyllite deposits observ-ed in Moore County is zoned. Zoning was first noted by Broadhurst and Council (1953) , p. 9) who stated : "A large deposit can be divided into three arbitrary units : a very siliceous footwall, a highly mineralized zone, and a sericitic hanging wall". The outer zone, surrounding the deposits, is a highly sheared country rock, enriched with hematite, chlorite, and chloritoid, which rapidly grades into unaltered rock away from the deposit. The contact between the outer and middle zones is sometimes exceptionally sharp, and occasionally cuts across the regional schistosity. The second or middle zone is a sericite schist still exhibiting faint relic beddings and containing minor chloritoid. This middle zone contains silicified bodies and, in the Phillips pit, chlorite bodies as well as abundant zones of pyrite cubes. The contact between the middle and inner zones is exceedingly gradational and poorly defined. The inner zone is always composed primarily of pyro-phyllite with some sericite and minor chloritoid. 23 The highest grade pyrophyllite always occurs in the center of this zone in the area of maximum shearing. Schistosity increases toward the center of the inner zone, which is eventually displaced by faulting. These fault planes are almost invariably intruded by quartz veins. Several generalizations can be made about zoning in the pyrophyllite bodies. These are: Shearing increases inwardly until a zone of rupture is reached, the amount of pyrophyllite decreases outwardly, the amount of chloritoid increases outwardly, and seri-cite is best developed in the middle zone and de-creases both inwardly and outwardly. Therefore, the zoning in these deposits may be classified as: 1. An outer magnesian and iron enriched zone; 2. A potassium or alkali zone; and 3. A high alumina zone. Discussion and Conclusions : The bulk chemical composition of the pyrophyllite deposits is essentially the same as that of the country rock. All of the chemical elements present in the pyrophyllite de-posits are present in the country rock, with the ex-ception of fluorine, copper and gold. These elements are associated with quartz veins and silicified zones and were obviously brought in from an outside source. The pyrophyllite deposits could have formed in place, with either addition or subtraction of chem-ical elements, if the elements were properly segre-gated and recrystallized into new minerals. A pos-sible sequence of events in the formation of pyro-phyllite deposits might be as follows : 1. Intensive folding and low grade regional meta-morphism accompanied by faulting. 2. Establishment of a temperature water pres-sure gradient across the shear zone, with high tem-perature and pressure in the center diminishing toward the sides. This would cause growth of the lower temperature and pressure minerals chlorite, chloritoid and hematite in the outer zones; the higher temperature and pressure mineral sericite in the middle zone ; and the highest temperature and pressure minerals pyrophyllite, diaspore and topaz in the central zone. Water vapor within the system would give the individual iron mobility to move in or out, as the case may be, causing previously exist-ing minerals to be replaced selectively. 3. Invasions of quartz veins, accompanied by silicification and introduction of fluorite, copper car-bonates, gold and pyrite as a separate event. In addition, at the Sanders prospect, the quartz veins caused recrystallization of the pyrophyllite in con-tact with the veins. 4. Removement along many of the faults, accom-panied by shearing of the quartz veins. 5. Cross faulting. 6. Minor overthrusting in the areas around the Womble and White pits. Gold Mode of Occurrence : Many of the gold mines in Moore County were originally worked as placers. Later, as mining deleted the original stream concen-tration, mines were opened in the primary ore veins. The largest number of these deposits occur in highly sheared felsic tuffs on the northwest side of the Robbins fault along Cabin Creek. Some of the ore occurs in rich quartz veinlets. However, the majority is disseminated throughout the country rock on either side of the veins. The ore bodies usually strike northeast and dip northwest parallel to regional schistosity. Orthoclase feldspars have been observed in some quartz veins suggesting that they were emplaeed at high temperature. Pardee and Park (1948) con-sidered the gold lodes of the southeast as high tem-perature deposits formed at considerable depth. They suggested that they were emplaeed during the orogony which occurred at the close of the Carbon-iferous period. Gold Mines Clegg Mine: The Clegg mine is located one and one-half miles west of Robbins. It was originally operated as an open cut mine, but sometime after 1900, two shafts were sunk on the ore vein. The main or Gerhardt shaft reached a depth of 128 feet and the second shaft reached an estimated depth of over 110 feet. The ore was ground on Chilean mills and the gold recovered by passing it over riffle boxes. These boxes were eventually replaced by copper plates. The deposit strikes north 25 degrees east and dips northwest at 75 degrees. The gold is disseminated throughout an ore zone 12 feet wide. The country rock is a felsic tuff sheared to sericite schist. The ore body contains a network of small quartz veinlets and is cross cut by reportedly barren quartz veins. Wright Mine : The Wright mine lies approxi-mately 150 feet northeast of the Clegg Mine. Prior to 1862, a shaft of unknown depth was sunk on this property. A second shaft was completed by J. W. Wright to a depth of 60 feet before the mine was closed in 1912. After grinding the ore on Chilean mills, the gold was recovered in riffle boxes. 24 The ore vein at this mine is a continuation of the vein found at the Clegg mine, and was reported to vary in width from 11 to 20 inches. The ore is disseminated through, what appears to be, highly manganese stained fault gouge. Cagle Mine : The Cagle mine is located 1500 feet southeast of the Clegg mine. The date this mine was first opened is not known, but it is thought to have been' operated in 1865 by Charley Overton. The mine operated sporadically until about the turn of the century, when it was closed. An attempt to de,water the old workings was made in 1906, but since that time the mine has laid dormant. The first shaft, an inclined shaft, reached a depth in excess of 171 feet ; a second shaft, approximately 50 feet southwest of the first reached a depth of 265 feet ; and a third shaft, further southwest, reach-ed a depth of 180 |
OCLC Number-Original | 4237160; 679951505 |
OCLC number | 4237160; 679951505 |
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