Vol. 27 August 1981 No. 3

FIELD GUIDE TO SELECTED PALEOZOIC ROCKS, VALLEY-RIDGE PROVINCE, VIRGINIA

PART I: ROANOKE, CLIFTON FORGE, FRONT ROYAL AREAS Thomas M. ~athri~ht,I1 and Eugene K.. Rader

This field trip is designed to show some of the exposed potential reservoir beds of age, structural style west of the mid- province front, Middle and Upper turbidite sequences, and structural style of the Blue Ridge front. The road log (Figure 1) at a field stop described in Bartholornew, Milici, and Schultz

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0.0 0.0 Begin trip one mile south of Ironto exit on Interstate Highway 81. Proceed north- - ward on Interstate Highway 81 and enter 1," - area of the Salem syncline which con- oowKILOMETERS tains rocks ranging in age from Middle MATCH LINE 0r.ra.. U r.rn () to L.ower (Price High Figure 1. Map of trip route and stop locations, bluffs to the east are fomed of brec- ciated rocks of the Elbrook Formation (Middle Cambrian) in the hanging wall CUMULATIVE INTERVAL of the Pulaski thrust system. MILEAGE MILEAGE EXPLANATION 1.0 1.0 Exit38 1.5 0.5 Bluff to west consists of nearly hori- and granites and gneisse zontal Upper Brallier Forma- of the Blue Ridge thrust sheet, which lies tion sandstones and shales for next mile. north, east and south of Roanoke. The 3.0 1.5 Cross the Pulaski thrust system at crest low lands just to the east are Middle and of ridge and continue on the hanging Lower Cambrian carbonate rock units of wall of the thrust for the next seven the Pulaski thrust system (Amato, 1974). miles to about exit 40. Mountains to the 7 Exit 40. Leave the Pulaski thrust system west are composed of Devonian and and enter the folded and faulted Silurian clastics of the Salem syn- and Ordovician rocks of the east limb of cline. The distant mountain range to the the Salem syncline (Amato, 1974). Be- east contains clastics tween exits 41 and 43, the low linear VIRGINIA DIVISION OF MINERAL RESOURCES

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ridge to the west (Green Ridge) marks are in the trough of a southwest .plung- - the outcrop of near vertical Silurian ing syncline that has reverse asymmetry sandstones (Tuscarora Formation). (steeper limb to east) as compared with 17 7 Exit 43 Tinker Mountain, ahead and to typical Appalachian synclines (Mc- the west, is separated from the main Guire, 1970). part of the Salem syncline by the Green 40.3 4.9 Abandoned quarry in overturned Mid- Ridge thrust which lies along the eastern dle and Lower Ordovician limestones in base of Green Ridge. The prominent the hanging wall of a fault seemingly mountains to the east (Reed and Coyner associated with the Pulaski thrust sys- mountains) mark the location of the tem. Reed-Coyner mountain window, where 40.7 0.4 STOP 1 - Junction of U.S. Highway 220 Ordovician through Middle Devonian and State Highway 43 at a magnificent rocks are within a Cambrian carbonate exposure known as "Eagle Rock in a rock terrain comprised of rocks from gorge on the James River. Rocks of the both the Salem syncline (west) and the Martinsburg (Upper Ordovician) to the Pulaski thrust system. Needmore(?) (Middle Devonian) forma-

21 4 Exit 44. Leave Interstate liixhway-. 81 at tions are repeated by faulting in ex- Cloverdale exit and proceed north on U.S. posures along U.S. Highway 220. The Highway 220. fault is at the location of the Need- 22.5 1.5 Daleville, leave Salem syncline and re- more(?) shale about 350 yards north of turn to Pulaski thrust system. A trans- the U.S. 220 - State 43 intersection. verse thrust ramp separating these The section south of the fault is the structures crosses U.S. Highway 220 in footwall and the northern part is the the northern outskirts of Daleville. hanging wall. It is our interpretation Locally the Lower Cambrian Rome that the fault flattened in the incompe- Formation overlies the Middle Cam- tent Needmore(?) shale at the top of a brian Elbrook Formation. The low dis- thrust ramp prior to the folding and ro- tinctive hills along the trip route are tation of the sections. The location of the formed by the Rome (McGuire, 1976). fault appears to be related to the position 27.1 4.6 East of the highway a segment of the of the mid-province structural front and Pulaski fault system has brought brec- rocks similar to those described at the ciated Elbrook dolomites over low dip- Fetzer Gap section in Shenandoah ping Conococheague limestones and County (Rader and Biggs, 1976). dolomites in the "Trinity syncline." 28.9 1.8 Fault slice of the Pulaski thrust system Measured Section: Footwall along U.S. Highway 220 at Eagle Rock containing Elbrook Formation and re- exposure beginning at fault about 350 yards north of intersection entrant of Middle Ordovician lime- of U.S. Highway 220 and State Highway 43. Portion below the stones and shales is located on outskirts contorted zone in the Keefer Sandstone modified from Diecchio of Fincastle. (1980). 29.3 0.4 Elbrook dolomites exposed on hill to the west in the hanging wall of a thrust; THICKNESS highway is on Middle Ordovician lime- (FEET) stones. Fault 30.2 0.9 The Fincastle conglomerate (a part of the Devonian: , Middle Ordovi- (3.0') cian) is exposed in the overturned limb 51 Shale, olive-green sheared ...... of a syncline on the east side of the Licking Creek Limestone (5.0') highway. The clasts in the Fincastle and 50 Limestone, medium-gray, laminated, associated conglomerates include re- chert cognizable rock fragments from Middle black ...... Ordovician through Lower Cambrian Silurian: formations (McGuire, 1970). Clifton Forge Sandstone (5.0') 30.5 0.3 Second exposure of Fincastle con- 49 Sandstone, light-gray, fine- to medium- glomerate in the upright limb of the fold. grained, cross-bedded ...... 5.02 31.0 0.5 Exposures of black fissile shale similar to the Paperville Shale (Ordovician) of Tonoloway Limestone (13.9') Southwest Virginia and the lowermost 48 Limestone, medium- to light-gray with black shales along the east limb of the dark shale interbeds, mudcracks ...... 13.9 Massanutten syncline in northern Augusta County and southern Rocking- Wills Creek Sandstone (205.5') ham County. 47 Sandstone, light-gray to white, fine- to 35.4 4.4 Middle Ordovician limestones and medium-grained, rusty brown on Beekrnantown dolomites are exposed weathering, calcareous, with clay no- on both sides of the road. These rocks dules; in part scree covered ...... 10.0 VIRGINIA MINERALS

THICKNESS (FEET) 40 Contorted zone. 90' wide 39 Sandstone, light-gray, fine-grained, with carbonaceous partings, trails on bedding planes, Skolithus and mud- cracks ...... (82.7') 38 Sandstone and clay shale, medium- light-gray, with some red staining ..... 37 Sandstone, fine- to very fine-grained, gayish-red-purple, hematitic ...... 36 Interbedded sandstone and clay shale. Sandstone, as above; clay shale, dark- greenish-gray, fissile, trails on bedding planes ...... Figure 2. West dipping reverse fault in the Wills Creek Sandstone 35 Clay shale to silt shale, dark-greenish- THICKNESS gray, fissile; interbedded medium- (FEET) light-gray sandstone, very thin-bedded 46 Sandstone, fine- to medium-grained, 34 Sandstone, medium- to coarse-grained, rusty brown on weathering, calcareous grayish-red-purple, hematitic, upper in part, bimodal cross-bedding ...... 55.9 3.0 feet pebbly, carbonaceous partings, 45 Sandstone, light-gray to white, fine- to trails on bedding planes; interbedded very fine-grained, bedding thin, some fine-grained, medium-light-gray sand- low-angle cross-bedding, ripple marks; stone ...... about 57 feet above base is a small, west Tuscarora Formation (139.8') dipping reverse fault (Figure 2); about 33 Conglomerate, rounded to subrounded 115 feet above base is a small an- quartz pebbles, 0.5 an maximum dia- ticline ...... 139.6 meter, medium-dark, black (carbon- "Bloomsburg" Formation (60.1', Figure 3) aceous?) matrix, carbonaceous partings. 44 Sandstone, purple with vertical green- 32 Sandstone, medium- to very fine- ish-gray "burrows"; shale, purple to grained, medium-gray, locally con- gray interbedded with white sandstone, glomeratic, subrounded quartz pebbles 4-inch shale at top of unit ...... 28.7 and black siltstone clasts, medium- 43 Sandstone, purple to light-gray, fine- to dark-gray shaly partings ...... very fine-grained, black cross-beds .... 15.7 31 sandstone, fine- to very fine-grained 42 Sandstone, purple with green mottles, medium-gray to light-gray, medium- to fine-grained, thin silty shale, vertical thick-bedded, Skolithus ...... greenish-gray "burrows" ...... 15.7 30 Sandstone, medium- to fine-grained, Keefer Sandstone (146' +) light-gray to light-olive-gray, black 41 Sandstone, light-gray, very fine- to specks throughout, black cross-beds, fine-grained with gray silty shale inter- interbeds and partings of carbonaceous beds ...... , ...... 72.4 materials ...... 29 Sandstone, medium- to fine-grained, medium-dark-gray to light-olive-gray, massive, black stains along joints ...... 28 Sandstone, medium- to fine-grained, pinkish-gray ...... 27 Sandstone, fine- to coarse-grained, variegated medium-light-gray, light- gray and light-brown, cross-bedded ... 26 Sandstone, fine- to very fine-grained, medium- light-gray, massive ...... 25 sandstone, fine- to very fine-grained, very light-gray, massive-bedded ...... 24 Sandstone, fine- to very fine-grained, medium-light-gray, massive ...... 23 Sandstone, fine- to very fine-grained, very light-gray, mediumlbedded ...... 22 Sandstone, fine- to very fine-grained, medium-light-gray, massive ...... 21 Conglomeratic sandstone, medium- to Figure 3. White unit on the left (east) is the Keefer Sandstone. The coarse-grained, light-gray, weathers dark beds are sandstone and shale of the "Bloomsburg" Formation. light-brown, quartz pebbles, 1 cm The light-colored sandstone in the upper right is the Wills Creek maximum diameter ...... Sandstone. 20 Carbonaceous silt shale ...... VIRGINIA DIVISION OF MINERAL RESOURCES Vol. 27

THICKNESS THICKNESS (FEET) (FEET) medium- to very thin-bedded; interbeds 19 Sandstone, very fine-grained, grayish- of medium-gray silty shale, weathers orange, massive ...... 4.0 light-olive-gray, channeling...... 8.5 18 Sandstone, coarse- to fine-grained, (upper 52.5') light-gray, some medium-dark-gray 5 Siltstone, medium-gray, weathers beds in upper 4 feet, cross-bedded, light-olive-gray, medium-bedded, olive-gray shale clasts ...... 26.0 slightly micaceous, some medium- 17 Sandstone, medium- to fine-grained, light-gray sandstone stringers, 2-cm medium-light-gray, weathers very pale- beds of fossiliferous sandstone at mid- orange to light-brown, medium- to very dle of interval (Lingula), channeling .... 2.0 thin-bedded, cross-bedded, rare olive- 4 Siltstone, fossiliferous, olive-gray, gray shale clasts ...... Lingula, gastropods, fossiliferous beds 16 Sandstone, fine- to very fine-grained, are phosphatic, some beds of Lingula light-gray, massive-bedded, cross-bed- coquina, occasional carbonaceous(?) ded ...... partings; medium-bedded, brownish- 15 Sandstone, medium- to fine-grained, gray sandstone at 1.5 and 3 feet above very light-gray, weathers light-brown, base ...... medium- to very thin-bedded, cross- 3 Sandstone, very fine-grained, dark- bedded ...... gray to brownish-gray with white 14 Sandstone, fine- to very fine-grained, specks that weather light-brown, with medium-light-gray, cross-bedded, black interbedded olive-gray, medium- to joint surfaces, some yellowish-gray, thick-bedded siltstone ...... 2-cm shale beds in upper 2-feet ...... 2 Siltstone, fossiliferous, olive-gray, 13 Sandstone, fine- to very fine-grained, weathers brownish-gray, Lingula ...... weathers light-brown, medium- to 1 Interbedded sandstone and shale, thick-bedded, cross-bedded, inter- sandstone, fine-grained, medium-gray bedded light-olive-gray silt shale in to medium-dark-gray, rare white specks upper 6 feet ...... that weather grayish-orange, very thin- Ordovician: to thick-bedded; silt shale to clay shale, Oswego Sandstone (36') medium-dark-gray, sandstone in- 12 Siltstone, light-olive-gray, weathers creases upward ...... 27.0 light-brown, good cleavage; 5-cm bed of END OF SECTION sandstone, fine-grained, light-gay, at 3 feet above base of interval...... 4.5 CUMULATIVE INTERVAL 11 Interbedded sandstone and siltstone, MILEAGE MILEAGE EXPLANATION sandstone, fine- to very fine-grained, medium-light-gray to light-olive-gray, 41.8 1.1 The steep, low, wooded hills to the west medium-bedded, cross-bedded; silt- are characteristic of the geomorphic stone, light-olive-gray, weathers light- forms developed on the Brallier For- brown ...... mation. Brallier and Millboro formations 10 Sandstone, fine- to very fine-grained, (Devonian) are exposed for the next nine light-bluish-gray, weathers light- miles. brown, thick- to very thin-bedded, 9.7 At the south (near) end of the bridge cross-bedded, occasional clasts and in- over the James River are good exposures terbeds of light-olive-gray silt shale, 1 of Devonian rocks; the Ridgeley (Oris- cm maximum clast size ...... kany) Sandstone and the uppermost 9 Interbedded litharenite and siltstone: Helderburg limestone (Licking Creek Litharenite, fine- to very fine-grained, Limestone). medium- light-gray, weathers pale-yel- 1.4 Town of Iron Gate. low-brown to pale-brown, thick-bed- 1.4 Rainbow arch, northern part of the Rich ded, micaceous, cross-bedded, some patch anticline. siltstone clasts; siltstone, light-olive- 1.6 Junction of U.S. highways 220 and 60 in gray; weathers light-brown ...... ~lifto; Forge. Turn left on U.S. 601220 8 Sandstone, fine- to very fine-grained, and proceed westward. light-blue-gray, weathers light-brown, 1.1 Intersection U.S. Highway 601220 and very thin- to thick-bedded, cross-bed- Interstate Highway 64, proceed west on ded, interbeds and clasts of light-olive- Interstate 64 to Covington. gray silt shale, 2 cm maximum clast size, 8.3 The anticline to the north is in the carbonaceous partings, black silt-shale Licking Creek Limestone; this structure interbedded at 4 feet below top of in- and parallel structures plunge obliquely terval ...... into the Rich Patch anticline (Figure 4). 7 Siltstone, medium-gray, weathers This junction of stuctures forms a major light-olive-gray, medium-bedded ..... lineament that separates the Central 6 Litharenite, fine- to very fine-grained, Appalachian fold trends from the greenish-gray, weathers lightlbrown, Southern Appalachian fold trends. No. 3 VIRGINIA MINERALS

Figure 4. Anticline in the Licking Creek Limestone (Devonian) Figure 5. View to south of Rainbow arch from Clifton Forge. Note along the Jackson River, view to the north. the west dipping reverse fault cutting ledges of Keefer Sandstone.

CUMULATIVE INTERVAL 8 N MILEAGE MILEAGE EXPLANATION EAGLE IRON WARM ROCK GATE SPRINGS I ? 68.0 2.7 Ex~tInterstate H~ghwav64 west at 6.5. H~ghway220 and re-enter 1-64 headed east. 79.2 11.2 Proceed eastward on Interstate Highway 64 to the first Clifton Forge exit. Follow U.S. Highway 601220 eastward through Clifton Forge to intersection of U.S. highways 60 (east) and 220 (south). :400

80.3 1.1 Turn right (south) on U.S. Highway 220 EXPLANATION and proceed to Iron Gate Community and turn around. TONOLOWAY LIMESTONE MILES 84.4 4.1 STOP 2 - Pull off to right in Iron Gate PALINSPASTIC DISTANCE zi McKENZlE FORMATION (Rainbow) gorge. Exposure of a classic 5 western Virginia anticline. From the g .=~'BLOOMSBURG"FORMATION r l_j_Il center of the arch at water level of the KEEFER SANDSTONE OSWEGO SANDSTONE Jackson River, a normal sequence Mar- ROSE HILL FORMATION /_""Y-j MARTINSBURG FORMATION tinsburg Formation (Upper Ordovician) f @ REEDSVlLtE FORMATION through the (Silurian) 1 is well exposed (Figure 5). The lower part of the arch is formed by the Tuscarora Figure 6. Stratigraphic relationships of sections at Eagle Rock, Iron Formation (Silurian) and the upper part Gate, and Warm Springs. See Figure 1 for locations. Note the by the Keefer Formation (Lesure, 1957). increase in sandstone to the south toward Eagle Rock. (Stratigraphic relationships between Eagle Rock, Iron Gate and Warm Springs are shown in Figure 6). The fold is strongly asymmetric with a well- CUMULATIVE INTERVAL defined kink fold on the west limb. A MILEAGE MILEAGE EXPLANATION northwest dipping reverse fault in the west crest is visible only from the Clifton containing Tioga metabentonite beds, Forge area. This anticline, as well as which occur throughout several hund- most other western Virginia anticlines, reds of feet of the shales in this area. was probably generated along a ramp These formations are at the surface along thrust arising from a decollement in the the west flank of the anticline to be seen subsurface. A question arises con- at Stop 3 and extend beneath the broad cerning the origin of this anticline: Does expanses of Upper Devonian clastics in the ramp-thrust zone crop out or does it synclines to the north. A decollement stay in the Upper Ordovician shales beneath the Upper Devonian rocks of (MartinsburgIReedsviIle) of the subsur- Brailler Formation would help to explain face? If it comes to the surface, the logical the intense folding in the Brailler south horizon for flattening would be the of Douthat State Park and along State Millboro-Needrnore shales at intervals Highway 42. VIRGINIA DIVISION OF MINERAL RESOURCES Vol. 27

Fiere 7. Millboro Shale breccia at Stop 3 containing rotated con- Figure 8. Millboro Shale breccia containing, bedded blocks of cretions and light-colored blocks of Needmore shale. Needmore shale.

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86.2 1.8 Return to intersection of U.S.Highway 60 and 220 in Clifton Forge. Turn right at Long Dale furnace; site of early iron ore traffic light onto U.S. Highway 60 east. smelting in the Clifton Forge iron dis- 86.4 0.2 STOP 3 - Park on left at Motor Sales trict. Corporation and walk back to west to Mile post 50, Trace of North Mountain community park. This exposure of fault; Conococheague rocks thrust over fracture in the Millboro and Beekmantown rocks. Needmore shale is at the lowest exposed Maury River. point in the northwestern part of the Junction of U.S. Highway 11 and In- Iron Gate anticline. Strongly cleaved to terstate Highway 64; continue east on pulverized Millboro Shale and shale Interstate 64. breccia surround intensely fractured to Exit 14, Junction of Interstate highways brecciated blocks of Needmore(?) 64 and 81; proceed north on Interstate shale (Figure 7). Rock type and fabric Highway 81. The Staunton fault zone in these exposures are similar to those in parallels the highway to exit 52, where the breccia zones (Max Meadows brec- the highway crosses onto the upper cia) associated with the Pulaski decoll- plate. ment to the east and to the fabric de- Mile post 202, Linear ridge to the west is veloped in the Chattanooga shale be- developed on steeply inclined .sand- neath the Pine Mountain thrust in stones of the Conococheague Forma- Southwest Virginia. Proceed east on U.S. tion. Highway 60. Mile post 206. Brownish scar at base of 1.5 Intersection of U.S. Highway 60 and mountain to the east is clay in the Cold Interstate Highway 64; proceed eastward Spring kaolinite pits located at the west on 1-64. foot of the Blue Ridge Mountains and on 0.5 On right are exposures of Millboro Shale the drainage divide between the showing features similar to those seen at Shenandoah and James River systems. last stop (Figure 8). These residual clay deposits are de- 2.3 To the west are bluffs composed of the veloped from Lower Cambrian lime- that display dishar- stones and shales and have been pro- monic and kink-band type folds that are tected from erosion by their position on characterisitc of folds in this rock unit the drainage divide. west of the Rich Patch anticlipe and the Exit 57. Conical wooded hills to the west anticline that conincides with Mill are developed from massive chert beds Mountain (ahead and to the left beyond in the Beckmantown Formation. the bluffs). Exit 60. Recross the Staunton fault and 1.1 Cowpasture River. enter the North Mountain fault block. 0.8 Helderburg limestones and Oriskany Mole Hill, the conical-shaped hill to the sandstones exposed on the left in the north-west, is an olivine basalt plug of road cut. age. No. 3 VIRGINIA MINERALS

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6.1 Exit 64, Hamsonburg, Note Massanut- . Contact zone is ten Mountain to the east; its southern about 150 yards east of U.S. Highway end is the south western limit of Silurian 340 bridge over Gooney Run. Seismic sandstones in Shenandoah Valley. and deep drilling data (Hams, 1979; 10.4 Exit 66, Mauzy. Ten miles to the west at Hams and Bayer, 1979a, 1979b; and Brocks Gap an anomalous Upper Or- Cook and others, 1979) provide evidence dovician-Lower Silurian sandstone for a model that explains the relation- section is exposed. An interpretation of ships between the structural styles of the this section is in Rader and Perry (1976). Valley and Ridge and Blue Ridge. Ac- 6.9 Exit 67, New Market. Turn right onto cording to Hams (1979) the rootless Blue U.S. Highway 211 east. Ridge anticlinorium was thrust west on a 0.5 Junction of U.S. highways 211 and 11. subhorizontal fault which ramped Turn left and proceed north on U.S. upward from a master decollement. Highway 11/211. Hams (1979) and Hams and Bayer 0.2 Junction of U.S. Highway 211 and 11. (1979a) suggest that Valley and Ridge Turn right and proceed east on U.S. rocks extend beneath the Blue Ridge Highway 211. Note the prominent wind anticlinorium. gap to the east. This gap, New Market END OF ROAD LOG Gap, occurs at a structural high in the plunge of the Massanutten synclino- rium, where the Massanutten Sand- REFERENCES stone is breached. Amato, R.V., 1974, Geology of the Salem quadrangle, Virginia: 3.8 STOP 4 - New Market Gap. Exposures Virginia Division of Mineral Resources Rept. Inv. 37,40 p. east and west of gap. During the late Bartholomew, M. J., Milici, R.C., and Schultz, A.P., 1980, Geologic Middle and Late Ordovician the eastern structure and hydrocarbon potential along the Salhille and portion of the Appalachian miogeocline Pulaski thrusts in southwestern Virginia and northeastern was subsiding rapidly and receiving Tennessee: Virginia Division of Mineral Resources Publication sediments from the east. Some formed 23, Part A. turbidites. Typical base - and top- Cook, F.A. and others, 1979, Thin-skinned tectonics in the cry- truncated Bouma cycles are preserved in stalline southern Appalachians; COCORP seismic-reflection the Martinsburg Formation in the profiling of the Blue Ridge and Piedmont: Geology, vol. 7, p. Massanutten synclinorium. The Mar- 563-567. tinsburg is overlain by the Massanutten Sandstone (Lower and Middle Silurian). Diecchio, R.J., 1980, Post-Martinsburg Ordovician stratigraphy, The deposition history of the Mas- central Appalachian basin: Unpublished Ph.D., thesis, Univer- sanutten Sandstone has been described sity of North Carolina, 220 p. by Roberts and Kite (1978). Proceed east Hams, L.D., 1979, Similarities between the thick-skinned Blue on U.S. Highway 211 to Luray. Ridge anticlinorium and the thin-skinned Powell Valley anti- 3.0 Typical Martinsburg turbidites are cline: Geol. Soc. America Bull. Part I, vol. 90, p. 525-539. exposed at places along the highway for Harris, L.D. and Bayer, K.C., 1979a, Eastern projection of Valley three miles. and Ridge beneath metamorphic sequences of Appalachian 2.5 South Fork Shenandoah River. In this (abs.): Am. Assoc. petroleum Geologists Bull., vol. 63, no. 9, p. area dishamonic, recumbent folds and 1579. klippen are in rocks underlying the Harris, L.D. and Bayer, K.C., 1979b, Sequential development of the Martinsburg Formation. Appalachian above a master decollement=Ahypothesis: Geo- 2.7 Luray Caverns on left in the Lower logy, vol. 7, p. 568-572. Ordovician Beekrnantown Formation. Lesure, F.J., 1957, Geology of the Clifton Forge iron district, Continue on U.S. Highway 211 bypass. Virginia: Virginia Polytech Inst. Bull., vol. 50, no. 7, (Eng. Expt. 2.0 Junction of U.S. highways 211 bypass Sta. Ser. No. 118), 130 p. and 340. Turn left onto U.S. 340 north. Proceed toward Front Royal. From here McGuire, O.S., lY/U, Geology of the Eagle Rock, Strom, Oriskany, to Stop 5 the trip route traverses Upper and Salisbury quadrangles, Virginia: Virginia Division of Min- ~ambaanand Lower Ordovician car- eral Resources Rept. inv. 24,89 p., bonate rocks. 1976, Geology of the Daleville quadrangle, Virginia: Virginia Division of Mineral Resources Rept. Inv. 42,43 p. 7.4 Rileyville. Rader, E.K. and Biggs, T.H., 1976, Geology of the Strasburg and 2.0 Compton. Toms Brook quadrangles, Virginia: Virginia Division of Mineral 4.3 Bentonville. Resources Rept. Inv. 45,104 p. 2.7 Limeton. 1.9 STOP 5 - Gooney Creek campground. Radar, E.K. and Peny, W.J., Jr., 1976, Reinterpretation of the Pull into campground and park. Along geology of Brocks Gap, Rockingham County, Virginia: Virginia Gooney Run, at the south side of the Minerals, vol. 22, no. 4 p. 37-45. campground, granodiorite of the Pedlar Roberts, W .P. and Kite, J.S., 1978, Syntectonic deposition of Lower Formation(?) (Precambrian) is on over- to Middle Silurian sandstones. Central Shenandoah Valley, turned beds bf the Lower Ordovician Virginia: VirginiaMinerals, vol. 24, no. 1p. 1-5. VIRGINIA DIVISION OF MINERAL RESOURCES Vol. 27

PART II: AREA NORTH OF ABINGDON ALONG U.S. 58A/19 Charles S. Bartlett, Jr. Bartlett & Associates, Abingdon, Virginia

CUMULATIVE INTERVAL MILEAGE MILEAGE EXPLANATION

0.0 0.0 Begin road log at the intersection of U.S. 11 (West Main St., Abingdon) and U.S. 19 about one mile west of the main bus- iness district of Abingdon. (Figure 1). 0.2 Proceed north on U.S. ~i~hwa~19. The first rock exposures on the right (east) are interbedded limestones and dolo- mites of the (Upper Cambrian); beds are inclined very steeply to the south or partially overturned to the north. These over- turned strata are on the southeast limb of a thrust faulted anticline. Just north are vertical, thin-bedded limestones of the Nolichucky Formation. 0.2 Intersection at right (east) with U.S. Highway 58 alternate; continue north on U.S. 58 A/19. 0.5 In right bank are exposures of fractured, gently inclined Honaker dolomite. State Road 848 (Old Cummings Heights Road) intersection from east. 0.4 Appalachian Power Company sub- station on right. A small thrust fault was Figure 1. Location Map. Measured section begins 0.1 mile north of mapped about 100 yards north of this Greendale Community. 1- . location. m 0.4 Scattered exposures of Honaker For- CUMULATIVE INTERVAL mation limestones and dolomites define MILEAGE MILEAGE EXPLANATION the surface axial trace of the Curnrnings Heights syncline. 0.3 Outcrops on right are Honaker dolomite 3.9 0.4 Opposite the Sunoco Service Station a beds which dip south into the Cum- wall built by the highway department mings Heights syncline. restrains portion of weathered carbon- 0.5 At right are low-dipping, thin-bedded ates of the lower part of the Copper limestone and shale of the Nolichucky. Ridge Formation in a landslide-prone This outcrop is in a fault-bounded slice area. in the base of the Pulaski thrust fault. 0.2 Shales and thin-bedded limestones of 0.3 Cross area of major offset along Pulaski the Nolichucky Formation are on the thrust fault, where the Honaker Forma- right. The beds contain brachiopods, tion (Middle Cambrian) is thrust onto trilobites and cystoid plates. Shale in- . upper Knox dolomites (Lower Ordovi- creases in the Formation to the north cian) with displacement of about 6000 and is dominant here. feet. 0.1 The lower portion of the Nolichucky 0.2 Upper Knox dolomite dips southward here contains several interformational and forms the upper portion of the Salt- limestone-pebble conglomerates (note ville thrust plate. the exposure adjacent to the "no park- 0.4 Carvosso United Methodist Church on ing" sign (Figure 2). right is on a narrow outcrop belt of the 0.3 On left (west) is medium-bedded basal Ordovician Chepultepec Forma- dolomite of the Honaker Formation. tion. Charles Butts was the first to note 0.1 Greendale Community; State Road 700 characteristic cephalopods at this intersection. locality. 0.1 Cross surface trace of Saltville thrust 0.1 There are good exposures on right of the fault which here has a displacement of upper portion of the Copper Ridge For- over 15,000 feet. Honaker Formation mation (Upper Cambrian) which is (Middle Cambrian) is thrust onto the dominated by dolomite but contains Pennington Formation (Upper Missis- some limestone, chert and distinctive sippian). Both formations are partly brownish sandstone interbeds. covered. No. 3 VIRGINIA MINERALS

UNlT THICKNESS NO. (FEET) nautiloids, and spiriferid and productid brachipods ...... 45 186 Argillaceous limestone, gray, thick- bedded; with abundant through- out: Pentremites blastoids, fenestrate bryozoans, five species of brachiopods, two species of pelecypods, crinoids and a horn coral ...... 67 185 Silty shale, gray, very carbonaceous grades upward in unit to calcareous silt- stone ...... 32 184 Silty shale, reddish-brown, calcareous, hackly, with abundant carbonaceous plant fragments on some bedding planes ...... 15 Figure 2. lntraformational limestone-pebble conglomerate in lower 183 Sandstone, dark-red-brown, very Nolichucky. fine-grained, thick-bedded ...... 7 182 Sandstone, gray, very fine-grained, In the following measured section, 5146.9 feet of Mississippian medium-bedded, with abundant plant rocks and older rock units are described. Portions of this section fragments, with shale interbeds ...... 21 were first described by Averitt in 1941. The author sampled and 181 Sandstone, gray, very fine-grained, described the section in 1968. The portion of the section herein thin-bedded; some shale, greenish- described for the Maccrady and Price formations was sampled in gray ...... 5 1970 and included in the author's dissertation on Lower Mississip- 180 Silty shale, dark-red and purplish- plan stratigraphy (Bartlett, 1974, p. 232-236.) Slagle (1978) recently brown, fossiliferous with three species studied the Hillsdale Limestone paleontology and paleoecology at of pelecypods, worm-trail-like mark- exposures in the section. Schmidt (1973) sampled the Price For- ings and plant fragments; few thin in- mation on this outcrop in his regional study. Near Benhams (about terbeds of purplish-brown, very fine- 10 miles to the southwest) 7080 feet of Mississippian rocks, possibly grained, calcareous sandstone ...... representing the thickest accumulation of Mississippian age de- 4.95 179 Siltstone, gray, thick-bedded, with very posits in North America, were traversed in an exploratory well large crinoid stem sections ...... drilled in early 1981 by Highlander Resources. The well was 178 Shale, gray...... spudded in the Pennington Formation. Mileage from Abingdon on 177 Siltstone, gray, dense, fossiliferous .... left side of column. 176 Silty shale, gray ...... 175 Siltstone and sandstone, very fine- UNlT THICKNESS grained, gray thick-bedded with some NO. (FEET) interbedded shale; some zones of abundant large crinoid stems (Figure 3) . Mississippian: 174 Silty-shale, gray ...... Pennington Formation (854+ feet) 173 Siltstone and sandstone, as unit 175 .... First (southernmost) 150 yards of exposure forms a 172 Shale with scattered rounded siltstone small anticlinal fold which is a repeat of units 191-188. "balls" to 2.5 feet in diameter suggesting Normal fault, displacement approximately 180 feet, lies in gully on left side of highway.

191 Shale, brownish-gray, and siltstone, dense, medium-to thin bedded, with oc- casional fossils ...... 106 190 Shale, greenish-gray and reddish- brown, fissile, and siltstone, medium- bedded ...... 38 189 Shale, gray, with some gray, arghl- aceous thin-bedded fossiliferous lime- stone, and some siltstone with rounded shapes suggesting slumping contem- poraneous with deposition...... 12 188 Sandstone and siltstone, gray, weathers to brown, calcareous, medium-to thin- bedded, fossiliferous, with thin gray shale partings ...... 34 187 Siltstone, gray, weathers to brown, dense, medium-bedded with fossili- Figure 3. Limy siltstone containing abundant large crinoid columnal ferous layers including the pelecypod sections in upper Pennington Formation (measured section unit Sulcatopinna rnissouriensis (Swallow), #175). VIRGINIA DIVISION OF MINERAL RESOURCES Vol. 27

UNlT HICKNESS NO. (FEET) n 158 Covered ...... 157 Argillaceous limestone, gray, thinly- laminated to medium-bedded, weath- ers to shaly appearance, dip 23" SE ...... 5.5 Fido Sandstone (43 feet) (exposed best on west side of highway) 156 Very sandy limestone, dark-red-brown, cross-bedded; weathers to friable sand- stone ...... 155 Hematitic sandstone, dark-brown, medium-grained, subangular to sub- rounded, thick-bedded, friable ...... Figure 4. Penecontemporaneous slump "balls" of limy siltstone en- Gasper limestone (738 feet) closed in shale of Pennington Formation (measured section unit 154 Argillaceous limestone, gray, thick- #172) on east side of U.S. 19-58A. Sledge hammer is 90 cm long. Dip bedded; crinoidal near top and with is 25"southeast toward Saltville fault which has concealed the axis of abundant Pentremites blastoids ...... the Greendale syncline. 153 Argdlaceous limestone, gray, partly covered ...... UNlT THICKNESS 152 Argillaceous and crinoidal limestone, NO. (FEET) gray, thick-bedded ...... slumping contemporaneous with de- 151 Crinoidal limestone, dark-red-brown, position. Exposed in high roadcut medium-grained, thick-to medium- (Figure 4) ...... 17 bedded, with three species of crinoids, 171 Siltstone and argillaceous sandstone, numerous Pentremites blastoids and gray, thin-to medium-bedded; moder- brachiopods ...... ately fossiliferous with brachiopods and 150 Argillaceous limestone, gray, weathers large crinoid stems ...... 90 to ihaly appearance; poorly exposed ... 170 Sandstone, light-gray, very fine- 149 Crinoidal limestone, light-gray, coarse- grained with large carbonized plant to medium-grained, medium-bedded . . stems ...... 5 148 Argillaceous limestone, gray, thick-bed- 169 Siltstone and sandstone, gray, very fine- ded; poorly exposed ...... grained, calcareous, with large pro- 5.9 Ste. Genevieve Limestone (1029 feet) ductid brachiopods ...... 55 147 Ferruginous, crinoidal limestone, dark- 168 Silty to sandy shale, gray, with sphe- red-brown, thick-bedded ...... roidal weathering ...... 18 146 Argillaceous limestone, gray, shaly 167 Shaly sandstone and siltstone, gray; weathered appearance ...... fossils include pelecypods and produc- 145 Ferruginous limestone, dark-red- tid brachiopods ...... 36 brown, medium bedded ...... 166 Shale, gray, platy, brittle, very fine- 144 Argdlaceous limestone, gray, weathers grained sandstone beds which become to brown, thick-bedded, zones of more numerous toward upper part of rounded clay pebbles...... unit; strike N 20" E, dip 25" SE. Base of 143 Shaly limestone, gray, very thin-bed- Pennington exposed at house on east ded ...... side of highway ...... 142 Sandstone, brown, fine-grained ...... 5.1 Cove Creek Limestone (876 feet) 141 Argdlaceous limestone, gray, weathers 165 Argillaceous limestone, gray, dense, to brown, medium-bedded ...... thick-bedded ...... 140 Limestone, gray, coarse-grained; fossils 164 Ferruginous limestone, dark-red- include bryozoans, brachiopods and brown, medium-bedded, with abun- crinoids ...... dant bryozoans in lower part ...... 139 Argillaceous- limestone, gray, weathers 163 Limestone, gray, dense...... to brown...... 162 Limestone, gray, dense, thick-bedded; 138 Shaly limestone, light-gray, weathers to zones of abundant fossils which contain brown; partly covered ...... brachipods and bryozoans including Archimedes sp ...... 137 Calcareous sandstone, gray-brown, 5.35 161 Limestone, gray, dense, fossils rare; be- fine-grained, dense, thin-bedded ...... comes shaly in middle part (best ex- 136 ~r~illaceouslimestone, gray, weathers to shaly appearance ...... posed on west side of road) ...... - - 160 Shale, black to dark-gray, crumpled, 135 Calcareous sandstone, gray, very fine- with slickensides ...... grained, uneven bedding, with scat- 159 Limestone, dark-gray, dense, thick- tered, rounded, gray-shale pebbles and bedded, dip 28" SE ...... shale partings; locally is siltstone ...... No. 3 VIRGINIA MINERALS

UNlT THICKNESS UNlT THICKNESS NO. (FEET) NO. (FEET)

Argillaceous limestone, light-gray, very fossiliferous including fenestrate weathers to brown, shaly bryozoan, productid brachiopods and appearance ...... 70 horn corals ...... 52 Shale, brown, slightly silty, sub-fissile . 12 110 Shale, black, fissile, calcareous, fos- Argdlaceous l&estone, gray, dense, siliferous ...... 2 thin-to medium-bedded ...... 55 109 Shaly limestone, gray ...... 10 Limestone, gray, dense, medium-bed- 108 Limestone, gray, dense, thick- ded ...... 62 bedded ...... 2 Crinoidal limestone, gray, coarse- 107 Limestone, gray, fine-grained, thick- grained, medium-bedded ...... 16 bedded, with crinoidal zones with Shaly limestone, gray, laminated with abundant crinoid Platycrinus penicillus carbonaceous fragments on partings ... 8 (Meek and Worthen), also horn corals . . 34 Limestone, greenish-gray, to dark-gray, 106 Crinoidal limestone, dark-gray, grades coarse-grained, thick-bedded; sulfur toward top of unit into cherty limestone odor on fresh break in top layers; fossils with irregular and rounded, gray chert include brachiopods and crinoids ...... 7 nodules, partly algal banded ...... 78 Argdlaceous limestone, weathers to 105 Oolitic limestone, light-gray, thick-bed- brown clay ...... 45 ded ...... 3 Limestone, dark-gray, coarse-grained, 6.5 Hillsdale Limestone (267.4 feet) thick-bedded; strong sulfur odor on 104 Limestone, light-gray, weathers to fresh break; very fossiliferous with greenish-gray, very fossiliferous includ- brachiopods and crinoids ...... 8 ing spiriferid brachiopods, nautiloids, Shaly limestone, light-blue-gray, silty, bryozoan, and a horn coral; weathers to hackly ...... 43 shaly appearance ...... Argdlaceous limestone, gray, thin-bed- 103 Limestone, gray, dense, some shaly par- ded, weathers to brown silty clay. 60 tings; zone of gray, algal-chert nodules Limestone, gray, thinly-laminated to in middle of unit; fossiliferous, espe- medium-bedded, ripple-marked ...... 5 cially in upper portion of unit (Figure 5) Limestone, light-gray, coarse-grained, 102 Shale, dark-gray to black, fissile ...... thick-bedded, fossiliferous ...... 16 101 Argdlaceous limestone, dark-gray, Argdlaceous limestone, gray, dense, thick-bedded, slightly fossiliferous ..... thick-bedded ...... 10 100 Argillaceous cherty limestone, dark- Argdlaceous limestone, light-gray, gray, with abundant algal banded gray laminated, weathers to shaly appear- chert nodules ...... ance ...... 1 99 Argdlaceous cherty limestone, dark- Limestone, light-gray, coarse-grained, gray, abundant light-gray to gray, partly with greenish-gray, widely spaced silty algal-banded chert nodules, massive- laminae ...... 11 bedded, fossils rare, dip 21" SE ...... Siltstone, gray-green, laminated red- 98 Oolitic limestone, light-gray, medium- disMrown, thick bedded ...... 13 to coarse-grained, with well-rounded Limestone, light-gray, coarse-grained, ooids; middle of unit with non-oolitic fossiliferous, oolitic ...... 1 layer ...... 6.5 116 Interbedded limestone, gray, coarse- grained and siltstone, gray-brown, thick-laminated. cross-bedded; with some reddish-to greenish-gray silty shale partings ...... 14 115 Limestone, gray, coarse-grained, medi- um-bedded, with layers of laminated greenish-gray siltstone ...... 64 114 Argillaceous limestone, gray, with abundant gray chert nodules, thick- bedded ...... 7 113 Calcareous siltstone, gray, weathering to gray-green, dense, thick-to massive- bedded;-shattered zone near base with calcite veinlets ...... 18 112 Ginoidal limestone, light-gray, coarse- grained, medium-bedded, fossils in- clude crinoids, brachiopods and horn corals ...... 10 Figure 5. Algal-banded and siliceous fossiliferous chert nodules in 111 Argillaceous limestone, light-gray, Hillsdale Limestone (measured section unit # 103). On freshly broken weathers to light-brown, thick-bedded, pieces the rock smells of petroleum. VIRGINIA DIVISION OF MINERAL RESOURCES Vol. 27

UNlT THICKNESS UNlT THICKNESS NO. (FEET) NO. (FEET)

97 Limestone, dark-gray, dense, thick- 82 Calcareous sandstone, light-gray, bedded, in part argillaceous, very fossili- weathers to brown, very fine-grained, ferous throughout (abundant bryozoan, medium-bedded, grades upward to three species; three species of brachio- arenaceous limestone, fossiliferous .... 10 pods, pelecypods, crinoiQs, horn coral 81 Argillaceous limestone, dark-gray, and the tabulate coral Syringopora vir- medium-bedded, with brachiopods in ginica Butts) ...... 101.7 upperpart ...... 20 96 Shaly limestone, gray, fossiliferous .... 16 6.85 80 Covered, formerly partly exposed be- 6.7 Little Valley Formation (549 feet; base of for- fore road was rebuilt. Averitt (1941, p. mation covered). (Highway "curve" sign is lo- 16) and Butts (1940, p. 356) found 90 feet cated near this boundary). of partially exposed sandstone and Note: At the western edge of Washington limestone which could be assigned to County, about 15 miles southwest of here, is the Little Valley Formation. The North located the Early Grove Gas Field which has Fork of the Holston River conceals an production from the Little Valley Formation and additional 146 feet of section which in- the upper sandstone member of the Price Forma- cludes the lower beds of the Little Valley tion. Formation ...... 236 (39.2 feet) (Partial exposure 95 Shale, gray, calcareous ...... on State Road 611 about '/z mile west of U.S. 94 Limestone, gray, medium-grained, fos- 19-58A). siliferous ...... 79 Mostly covered by State Road 611, upper 93 Shale, black, coaly, with lustrous sur- part of unit is exposed above road on faces, contorted ...... south bank of river. Clay shale, partly 92 Agillaceous limestone, gray, dense to silty, pale-olive, yellowish-gray, and shaly, strong odor in fresh break in grayish-red. Yellowish-gray shale is lower part; very fossiliferous with dolomitic ...... 39.2 abundant bryozoans, three species of 7.1 (751.3 feet) brachiopod, and a horn coral, dip 27" Hayters Sandstone Member (137.8 feet) SE ...... 82 78 Arkosic sandstone, fine to medium- 91 Shale, dark-gray, fissile, with one thin grained, subrounded, light-gray- bed of dense limestone near top, fos- brown, coarse muscovite flakes, fair siliferous in part ...... 40 porosity; contains one-inch-thick layer 90 Argillaceous limestone, gray, dense, bf quartz-pebble conglomorate with abundant fossils with bryozoan and pebbles to 15 mm ...... 8.5 productid brachiopods ...... 28 77 Sandstone, very fine-grained, angular, 89 Shaly limestone and shale, gray, tali medium-gray, sparsely carbonaceous, careous, slightly fossiliferous ...... :.. 17 very fine to medium muscovite, med- 88 Limestone, gray, dense, strong sulfur ium-bedded, tabular cross-laminated, odor on fresh break, with a few gray rare imprints of brachiopods; about 8.5 chert nodules in upper part; coral bio- feet above base is a interval of quartz hem composed of large colony of tabu- pebbles to 20 rnrn., another pebble in- late corals (exposed in highway median terval at 12.0 feet above base of unit. At area) ...... base is thin parting of slightly silty shale, 87 Shaly limestone, gray, thinly-laml- micaeous, light-gray ...... 18.0 nated, rare fossils ...... 76 Arkosic sandstone, coarse- to very 86 Siltstone and sandstone, brown to coarse-grained, with scattered quartz light-gray, very fine-to fine-grained, pebbles, and subrounded pebbles to 49 calcareous ...... mm on upper bedding plane, pale-yel- 85 Limestone, gray, dense, sulfur odor on lowish-brown ...... 5.0 fresh break, calcite-lined geodes ty 0.5 75 Arkosic sandstone, very fine-grained, inch diameter common, thick-bedded; olive-gray, trace of very shiny coal sparsely fossiliferous ...... grains, fine muscovite flakes, medium- 84 Shaly limestone, dark-gray, with two bedded, thin-laminated ...... 8.5 dense argllaceous limestone beds in 74 Covered interval ...... 4.0 middle portion, abundant fossils with 73 Arkosic sandstone, fine- to medium- three species of brachiopods, four grained, with rare coarse grains, sub- species of bryozoans, two species of angular pebbles to 20 mm on top bed- pelecypods, crinoids, horn and colonial ding plane, grayish-brown, medium- rugose corals ...... bedded, cross-laminated, cross-bedding 83 Limestone, blue-gray, medium-grain- dipping 26" E and 28" S60°E, top surface ed, with dark-gray rounded chert no- wavy ...... 7.0 dules, thick-bedded; fossils include 72 Arkosic sandstone, fine- to medium- brachiopods, bryozoans, and grained, subangular, very pale-orange crinoids ...... feldspar grains, few flakes muscovite, No. 3 VIRGINIA MINERALS

UNlT THICKNESS UNlT THICKNESS (FEET) NO. (FEET)

scattered rounded quartz pebbles to 8 62 Very slightly silty shale, light-olive- nim, mostly in upper part...... gray, very fine muscovite, hackly ...... 71 Concealed by river terrace gravels ..... 61 Glauconitic siltstone and silty shale with 70 Partly covered. Interbedded coarse silt- glauconite concentrated in four zones at stone to very fine-grained sandstone, 3.0-4.0, 6.0-6.5, 9.9-10.4, and 21. 3-24.3 light-gray, very fine muscovite, very feet above unit base; imprints, thin-bedded and silty shale ...... mainly in upper zone, include Chonetes 69 Interbedded argillaceous sandstone, sp., and Spirifer zuinchelli brachiopods, very fine-grained, slightly glauconitic, Fenestrellina sp. and Rhombopora sp. dense, light-olive-gray, carbonaceous, bryozoans, ostracodes, and crinoid few imprints of Chonetes sp. and Pro- columnals ...... ductella sp. brachiopods, and coarse silt- 60 Glauconitic shale, very silty, dusky-yel- stone, medium-gray, trace amounts of lowish-green, glauconite very fine- very fine muscovite, some spheroidal grained, very fine muscovite, and silt- weathering ...... stone, fossiliferous, trace amounts of Greendale Member (290.2 feet) (Exposed in scattered glaucontie, light-yellowish- bank behind ARC0 service station across the brown, very fine muscovite, fossils in- liigliwav from intersection of State Road 8) clude Fenestrellina sp. and Rhombopora sp. and crinoid columnals ...... 7.3 68 Interbedded argillaceous siltstone, 59 Interbedded very silty shale, grayish- light-gray, very fine muscovite; sand- brown, micaceous, and siltstone, light- stone, very fine-grained, slightly glau- grayish-brown, very fine muscovite, conitic, light-oliv&ray, @aGonite very scattered dark-green, very fine to fine dark-green, very fine muscovite, fossil grains of glauconite ...... fragments, very thin-bedded and silty 58 Covered interval......

' shale, medium-light-gray, carbo- 57 Poorly exposed. Slightly silty shale, naceous; siltstone/sandstone ratio grayish-orange, micaceous, and very 112...... fine-grained sandstone, light-gray, 67 Silty shale, slightly glauconitic, light- partly very thin-laminated; one thin bed olive-gray, glauconite very dark-green, ferruginous, fossiliferous with Syring- very fine muscovite, partly weathers othyris sp., lowspired gastropods, crin- spheroidal, few fossils in thin ferrugin- oid columnals, and bryozoans ...... ous bed, with Spirifer sp. and Syring- 56 Argillaceous ferruginous sandstone, othyris sp ...... brownish reddish-purple, very fine- 66 Argillaceous siltstone, light-gray, partly grained with subrounded coarse to very ferruginous, light-olive-gray, very fine coarse grains scattered, very fine mus- muscovite, about 10.0 feet above base covite, friable...... some molds of Spirifer sp.; some silty 55 Ferruginous sandstone, fine- to very shale in upper part, light-gray, slightly coarse-grained, conglomeratic in upper glauconitic, very fine muscovite ...... part with subrounded pebbles to 10 mm, 65 Sandy siltstone, slightly glauconitic, some siltstone and feldspar, grayish- light-gray, partly stained brown, very reddish-purple ...... fine quartz grains, very fine muscovite, 54 Partly covered. Shale, yellowish-gray, fossiliferous, with Spirifer bifurcatus(7 ) very fine muscovite, carbonaceous, with Productella sp., and Spirifer solidirostris(7) minor interbedded siltstone, very thin- brachiopods, Fenestrellina sp., Cystodict- bedded ...... ya sp. bryozoans, and crinoid colum- 53 Sandstone, feldspathic, medium- to nals. very coarse-grained, subangular, spar- 64 Glauconitic shale, silty, dusky-yellow- sely carbonaceous, thick-bedded; one ish-green to grayish-green, very fine bed ferruginous, reddish-brown ...... muscovite, glauconite most abundant in 52 Very silty shale, light-gray, micaceous, two beds 0 to 0.5 feet and 4.3 to 5.5 feet carbonaceous, blocky; with interbeds of above base ...... arkosic sandstone, very fine-grained, 63 Silty shale, medium-light-gray, very angular, dense, light-gray ...... fine muscovite, very fossiliferous with Broad Ford Sandstone Member (217.3 feet) imprints of Syringothyris texta, and Pro- 51 Interbedded sandstone (40%) and shale ductella sp. brachiopods, Fenestrellina (60%) with thin- to medium-bedded sp., Rhombopora sp. bryozoans, large sandstone layers spaced at 0.5- to 1.5- pectenoid clam (44 mi.;l by 46 mm ) foot intervals. Sandstone, feldspathic, crinoid columnals, and carbonaceous medium- to very coarse-grained, sub- plant stems ...... angular, very light-gray, fair porosity, VIRGINIA DIVISION OF MINERAL RESOURCES Vol. 27

UNIT THICKNESS UNlT THICKNESS NO. (FEET) NO. (FEET)

some sandstone very fine-grained, light- Big Stone Gap Shale Member (20.6 feet) (Ex- gray, micaceous. Silty to sandy shale, posed on hillslope about 300 yards east of high- light-gray, very micaceous, some felds- way.) par ...... 61.0 7.55 42 Silty shale and clay shabe, dark-gray to 50 Silty shale, medium-gray, medium to medium-dark-gray, brittle, fissile ...... coarse muscovite, slightly carbonaceous Cloyd Conglomerate Member (22.0 feet) with 25% interbeds of quartzitic sand- (Exposed on hillslopes off highway.) stone, very fine-grained, angular, thin- 41 Sandstone, fine- to very fine-grained to medium-bedded. Normal fault with with lensing beds to 5.0-foot-thick 1.0 foot d~splacementnear top of unit. quartz-pebble conglomerate, rounded Rare Chonetes sp. impnnt ...... 44.7 pebbles to 20 mm., dense, clean, quart- 49 Arkosic sandstone, quartzitic, very zitic, medium- to thick-bedded ...... fine-grained, angular, light-gray ...... 1.2 Devonian: 48 Sandy, arkosic shale, medium-gray, "Chemung" Formation (147.6 feet) (Exposed on very micaceous, sparsely carbonaceous, hillslopes off highway). varies in thickness 3.7 to 3.0 feet; con- 40 Covered interval. Some fossiliferous tains two very thin beds of sandstone, siltstone float with Carnarotoechia sp. very fine-grained, quartzitic, grayish- brachiopod imprints ...... 103.0 brown, cross-laminated ...... 39 Siltstone, medium-gray, very mica- 47 Arkosic sandstone, quartzitic, fine- ceous, few carbonaceous plant frag- grained, angular, light-gray, with 0.2- ments, very thin- to thin-bedded, thinly foot-thick shale bed in middle, sandy, laminated ...... 5.6 arkosic, medium-gray, very carbona- 38 Partly covered. Siltstone, very fine ceous with plant stem fragments, mica- muscovite and slightly silty shale ...... 28.0 ceous ...... 37 Argillaceous siltstone, light-olive-gray, 46 Interbedded sandstone and shale bedding surfaces brownish-gray, very (25%). Sandstone, arkosic, argillaceous fine muscovite, very thin- to medium- in part, quartzitic in part, fine-grained, bedded, some plant fragments ...... 11.0 medium- to light-gray, carbonaceous, Brallier Formation (679 feet &, top and base of medium to coarse muscovite, very thin- formation covered.) to thick-bedded, cross-bedded, dips 18" 36 Covered interval ...... 42.8 S15"W, ripple-marked, crest to crest 5.1 7.7 35 Slightly silty shale, light-olive-gray, inches, trough trend N85"W. Silty shale, very fine muscovite, very fine carbona- medium-gray, micaceous, slightly car- ceous plant fragments; few siltstone bonaceous, hackly. Clay-pebble con- beds, light-olive-gray, very fine mus- glomerate on one bedding plane near covite, some disc-shaped specimens of

top ...... Sporanxites-. sp., very thin-bedded ...... Sandstone, very fine- to fine-grained, 34 Shale, greenish-gray to gray-brown angular, dense, light-gray with some weathers to light-yellow, hackly; partly medium-light-brownish-gray in lower exposed along highway and in creek bed 15 feet, medium to very coarse musco- east of highway...... vite, few carbonaceous fragments, clay Millboro Shale (684 *,feet: top and base of for- pebbles on some bedding, thin- to mation covered) thick-bedded, even, flat bedding; some 33 Mostly covered, except for two small arkosic beds; 2.0-foot-thick fractured outcrops of shale in creek east of high- zone 15.0 feet above base. Few silty way dark-gray, hackly to fissile, with shale partings in lower 15.0 feet ...... very fine mica ...... Interbedded sandstone, fine-grained, Huntersville Formation (83.9_+feet: top and base angular, dense, light-gray, micaceous, of formation covered.) very carbonaceous layers, even 8.4 32 Chert, light-gray to white, blocky, med- medium-bedded, and very silty shale, ium-bedded, fossiliferous; poorly ex- mottled gray and brownish-gray, mica- posed in creek, roadcut excavated in ceous ...... 1969 exposed chert and sandstone con- res Member (63.4 feet) taining eight brachiopod and one gas- Silty shale, partly sandy, medium-gray tropod species ...... to olive-gray, very micaceous, fine to 31 Covered: probably shale and sandstone very coarse flakes, layers very carbon- (may include Oriskany and Keefer sand- aceous, subfissile to partly pencil; stones) ...... minor, very thin-bedded sandstone, very fine- to fine-grained, slightly ar- 30 Conglomeratic sandstone, light-gray to kosic, dense, light gray, few carbonized purplish-brown, medium- to very plant stems. Normal fault with about coarse-grained with rounded, frosted 20.0-foot displacement about 40.0 feet quartz pebbles up to 10 mm diameter below unit top ...... 63.4 massive- to thick-bedded ...... No. 3 VIRGINIA MINERALS

UNlT THICKNESS UNlT THICKNESS NO. (FEET) NO. ,(FEET)

Silurian: 4 Sandstone light-brown with reddish-to Rose Hill Formation (147.5-+feet) yellowish-brown iron-stained laminae, 29 Siltstone and sandstone, dark-pur- fine- to medium-grained, massive-bed- plish-brown fine-grained, dense, med- ded, planar cross-bedding: ripple-mark- ium- to thick-bedded ...... ed surfaces with crest line trend So40" E; 28 Silty shale, reddish-brown and light- quartzitic ...... greenish-gray ...... Ordovician: 27 Siltstone, dark-purplish-brown, medi- Juniata Formation (26-+feet) um-bedded ...... 3 Covered: probably siltstone ...... 26 Interbedded siltstone, thin-bedded, and shale, light-brown, with polished bed- 2 Siltstone, maroon and gray, thin- to ding surfaces ...... medium-bedded, with worm-boring- 25 Sandstone, gray to dark-gray, fine- like markings...... grained, medium- to thick-bedded: 1 Interbedded silty shale, hackly, and grades upward to silty sandstone ...... siltstone, purplish-red, grades upward 24 Clay shale, light-gray, fissile ...... into mottled greenish- and purplish- 23 Clay shale, light-gray, fissile, with thin gray, knobby, thin- to medium-bedded. interbeds of siltstone ...... 8.9 Highway cross-over to John Douglas Memorial 22 Siltstone, gray, dense, thick- to thin- Wayside. bedded ...... END OF ROAD LOG 21 Fermginous shale, mottled brown, with oolitic iron structures ...... 20 Siltstone, light-gray, with some red- brown tubular worm borings perpen- REFERENCES dicular to bedding, with interbedded ferruginous shale partings ...... 19 Shaly siltstone, dark-purplish-brown, Averitt, Paul, 1941, The Early Grove Gas Field, Scott and Wash- weathers mottled, medium-bedded .... ington counties, Virgnia: Virginia Geol. Survey Bull. 56,50 p. 18 Siltstone, iron-stained brown to purple, Bartlett, C. S., Jr., 1974, Anatomy of the Lower Mississippian delta thick-bedded ...... in southwestern Virginia: Ph.D. dissertation, Univ. of Ten- 17 Shaly siltstone, mostly covered ...... nessee, Knoxville, p. 232-236. Tuscarora Sandstone (196.1f feet) Butts, Charles, 1927, Oil and gas possibilities at Early Grove, Scott 8.5 16 Sandstone, light-gray, quartzitic, County, Virginia: Virginia Geol. Survey Bull. 27,12 p. thick-bedded ...... 15 Siltstone, light-purplish-gray, thick- Schmidt, G. L. 1973, The Price Formation, southwestern Virginia bedded ...... and southeastern : M.S. thesis, University of 14 Silty shale, gray ...... South Carolina, 44p. 13 Sandstone, light-gray, quartzitic, thick- Slagle, E. S., 1978, The paleontology and paleoecology of the bedded ...... Hillsdale Limestone (Mississippian, Meramecian), Washington 12 Shale, light-gray, slightly silty with County, Virginia: M.S. thesis, East Carolina University, 175 p. some gray, thin-bedded siltstone ...... 11 sandstone, light-gray, quartzitic, medium- to thin-bedded ...... 10 Sandstone, gray, fine-grained, dense, siliceous, thin- to medium-bedded with SCHEDULED MEETINGS thin argillaceous beds at top ...... 9 Mostly covered: two beds of medium- October 23-25, Carolina Geological Society, Gaf- bedded quartzitic sandstone crop out; hey, South Carolina (Carolina Geological Society, dip 22" SE ...... Box 6665, College Station, Duke University, Durham, 8 Quartzitic sandstone, light-gray, mas- NC 27708). sive ...... 7 Silty shale, light-gray, with siltstone lense in middle ...... November 2-5, Geological Society of America, Cin- 6 Quartzitic sandstone, light-brown, fine- cinnati, Ohio (Lois J. Campbell, Dept. of Geology, to medium-grained, massive- University of Kentucky, Lexington, KY 40506). bedding ...... 5 Quartzitic sandstone, light-brown, fine- November 5-6, Virginia Association for En- to medium-grained, massive-bedding, with planar and festoon cross-bedding; vironmental Education, Skyland, Shenandoah depositional dip computed to be 3"-5" National Park (Tim Tigner, Division of Forestry, Box N4TW ...... 3758, Charlottesville, VA 22903). Virginia Division of Mineral Resources Virginia Minerals Box 3667 Second-class postage paid at Charlottesville, VA 22903 Charlottesville, Virginia. ISSN 0042-6652 Return Postage Guaranteed

NEW PUBLICATIONS

PUBLICATION 28 PUBLICATION 31 Lineament and Fracture Trace Analysis and Its The Geology of Glen Allen Quadrangle not only Application to Oil Exploration in Lee County, Virginia describes the geology of the area but also lists geologic by Thomas M. Gathright, 11, has just been published and economic factors affecting land modification of by the Division as Publication 28. Linear traces from the rock units. Interpretive cross-sections are also aerial photography and LANDSAT imagery are used included with the map. The text portion of the pub- to evaluate oil producing areas. The methodology lication discusses the availability of materials suitable of interpreting these linear traces and positioning for producing crushed stone, bricks, and coal. The them on geographic bases is discussed in the pub- usefulness of the rock units for solid and liquid waste lication. The fracture traces, related by means of disposal, building and road construction, and water Cartesian Azimuth distributions and rose diagrams, supply are also indicated. Publication 31 is available are shown on 21 separate topographic maps. These from the Division for $4.62 postpaid. maps also show the location of 126 test wells in the county. The publication also gives information on oil PUBLICATION 32 bearing strata, their structural position, and their Publication 32, High-silica Resources in Augusta, relation to linear traces. Bath, Highland, and Rockbridge Counties, Virginia Publication 28 is available from the Division for is available for $3.06 postpaid. Physical descriptions, $3.84 postpaid. sieve analyses, and chemical test data are presented so that the commercial potential of high-silica resources in these counties can be evaluated. PUBLICATION 30 Most of the area's silica resources are contained The Geology of Hanover Academy Quadrangle, within the Antietam and Tuscarora formations and the Virginia is available for $4.62 postpaid. The map Keefer and Ridgeley sandstones. A total of 249 sand- shows the distribution of rock units on a topographic stone and quartzite localities were examined. Com- map base with interpretive cross-sections. Present or posite samples from each of the principal resource historical economic resources of the area include units were analyzed for silica content in a raw or gravel, crushed stone, dimension stone, iron, mica, unbeneficiated condition; silica content of the units coal, and zircon. The publication also discusses soil ranges from 97.2 to 99.1 percent. The percentage of types, excavation problems of the area; and water silica in beneficiated samples ranges from 98.9 to 99.5 possibilities. percent for the same samples. Grain-size distribution, average grain size, and degree of sorting for most samples are shown by histograms and cumulative frequency curves. The study is similar to an earlier publication on the silica resources of five northwestern Virginia Minerals Vol. 27, No. 3, August 1981. Virginia counties.