Vol. 26 February 1980 No. 1 ROAD LOG TO THE GEOLOGY OF THE ABINGDON AND SHADY VALLEY QUADRANGLES Charles Bartlett and Thomas Biggs ABINGDON QUADRANGLE This road log is a guide to some of the significant geologic features in the Abingdon and Shady Valley quadrangles. The low- er Paleozoic rocks in this area are mainly carbonates and shales. kt places fossil gastropods are in the carbonates and there are graptolites in the Athens shales. The strqta lie in a sequence of major folds, bd& o$en and overturned, characteristic of the OR 1 G 1 Ridge and Valley province. The route crosses these structures and also the Pulaski, Spurgeon and Alvarado thrust faults and the Dry Run cross fault. Cataclastic rocks are associated with the faults. Karst topography is well developed in the Holston River Valley. A generalized map of the area showing the 41-mile route of the road log is shown. Topographic maps of the Abingdon and Shady Valley quadrangles may be obtained from the Virginia Division of Mineral Resources, Box 3667, Charlottesville, Virginia 22903. A county road map of Washington County is available from the Information Office, Virginia Department of Highways, 1221 East Broad Street, Richmond, Virginia 23219 or the Residency Shop in Ablingdon. Permission should always be obtained before entering private property. CUMULA TIVE DISTANCE DISTANCE EXPLANA TION MILES MILES Km Km 0.0 0.0 Begin in Abingdon at the fire hydrant 0.0 0.0 on Main Street (U. S. Highway 11) in front of the Martha Washington Inn. Head east. QUADRANGLE r---- 0.4 0.4 Washington County Courthouse on left. 0.64 0.64 0.5 0.1 House on left. Behind house is "Wolf 0.80 0.16 Cave" formed in Chepultepec limestone. It is said that wolves from this cave VIRGINIA 012 attacked a party led by Daniel Boone, @- hence an early name for Abingdon was Wolf Hills. Index map for road log. VIRGINIA DIVISION OF MINERAL RESOURCES CUMULA TI VE CUMULATIVE DISTANCE DISTANCE EXPLANATION DISTANCE 1>/STANCE EXPLANATION MILES MILES MILES MILES - Km - Turn left onto Tanner Street. Turn right onto road to E. B. Stanley Elementary School. Turn right onto Valley Street. Outcrops of Conococheague sand&one and limestone on right in front of Turn left onto State Road 692 (White school. Mill Road). On right behind the William Neff Technical School (circular building) is Sandstone from the Conococheague thick-bedded Chepultepec limestone. Formation in the right roadbank. Turn left onto State Road 749 at County Shale chips weathered from the Noli- school office building. chucky in the right roadbank. Stop sign. Turn left on U. S. Highway Conococheague and Nolichucky beds 11. are overridden by the Honaker dolomite Cross Norfolk ddWestern Railway along small thrust fault. overpass. ,Road junction with State Road 695, STOP 3. Spurgeon fault trace with bear left and continue on State Road bouldery breccia exposed on both sides 692. of the highway. Breccia is in near In left roadcut is Honaker dolomite vertical beds of the Honaker Formation which has south dip. which was thrust upon the Knox Group, In right roadbank is fractured Honaker upper part. The fault overlies a portion dolomite. of the axial trace of the Abingdon syn- STOP 1. Honaker dolomite with abun- cline. Continue to southeast on U. S. dant fractures and calcite veins on right Highway 11. in roadcut. Zone is near the base of a Turn left at Texaco station onto service secondary thrust sheet associated with road on north side of Interstate High- the Pulaski fault. Continue north. way 81. The small valley on the right lies on the Turn left onto State Road 1620. trace of the main Pulaski thrust fault along which the Honaker Formation is STOP 4. Walk 50 yards west to small in contact with the Knox Group, upper waterfalls in Fifteenmile Creek; &%eFT# part. falls are formed in Nolichucky lime- Outcrops in right road bank are dolo- mite with white chert of the Knox stone beds. Beds here are representa- Group, upper part. tive of this unit in areas south of the Return south to State Road 695. Spurgeon fault. The reddish-brown, wavy, silty, raised laminae in the bluish- Turn left onto State Road 695. gray micrite is distinctive. Note also thin lenses of oolitic, fossiliferous lime- Some deep sinkholes on the left in a stone-pebble conglomerate. The site of limestone and dolomite unit in the an ancient Indian campground was middle portion of the Honaker Forma- partially excavated here in 1972. A tion. charcoal sample from the site dated Turn right onto State Route 697. 585 A.D. Continue north into a housing development. Turn around. The Spurgeon fault may Outcrops on left: dolomite in upper be traced on the hill to the west (across part of Honaker Formation. the creek). Nearly vertical beds of Weathered Nolichucky shale in left road- Honaker Formation and more gently bank. inclined beds of Chepultepec limestone Sandstone layers near base of Conoco- are north of the fault. The strike of the cheague Formation in left roadbank. Honaker beds is almost perpendicular On left limestone and dolomite of to that of the Chepultepec. Return to Conococheague Formation. Note springs near the creek. U. S. Highway 11. STOP 2. Conococheague Formation Stop sign. Turn left onto U. S. High- outcrops are on left of road. Rocks of way 11. this unit include light-gray dolomite, Pass under Interstate Highway 81. laminated bluish-gray limestone and a layer of limestonepebble conglomerate. Turn right onto U. S. Highway 58 (J. Abandoned quarry on left at curve is in E. B. Stuart Highway). Conococheague Formation dolomite Overturned and cleaved, graptolite- and limestone. bearing Athens shales in right roadcut. Turn left onto State Road 699. Turn left onto State Road 769, a gravel 4 road. No. 1 VIRGINIA MIN.ERALS CUMULATIVE CUMULA TIVE DISTANCE DISTANCE EXPLANATION DISTANCE DISTANCE EXPLANATION MILES MILES MILES MILES Km Km Km STOP 5. Large borrow pit in Athens Roadcut on left in Conococheague Formation shale which contains beds limestone with two prominent sand- with thin siltstone partings and axial stone beds. Just beyond is junction plane cleavage. Dip is about 35 degrees with State Road 783; turn right and to the northwest into the Great Knobs continue on State Road 710. syncline. Continue south. STOP 6. Roadcut in limestone and Quarry on left in limestones of Lenoir- dolomite assigned to the Chepultepec Mosheim and dolomite of Knox Group, and Knox Group, upper part. Note upper part. Stop sign; turn left onto terrace gravels high on outcrop at left. U. S. Highway 58. Walk ahead 50 yards to bridge on south Road is at angle of dip slope of Conoco- Fork Holston River. Upstream are cheague beds. rapids of resistive Lenoir-Mosheim Crest of hill is at axis of Watauga anti- limestone. The trace of the Alvarado cline. cross fault is beneath the west end of Roadbank exposures of south dipping the bridge. dolomite in Knox Group, upper part. Cross bridge. Hill on right ahead is of Hillside cuts in Athens Formation. Athens Formation. Alvarado community. Bridge over Middle Fork Holston River. Cross Norfolk and Western Railway Rapids on right in river formed by re tracks. sistive sandstone and siltstone layers Turn right onto State Road 674. in Athens Formation near axis of River Knobs syncline. Outcrops near road are Knox Group, Road cut through dark-gray, fissle upper part. shale of Athens Formation with thin About 100 feet at right, Lenoir-Mosheim layers of sooty-gray bentonite (?) and limestones terminate against Athens with pyrite and tiny gypsum crystals. shale at a normal fault. Beyond, about Roadway on dip slope of dolomite in 150 yards north of the road, is an ex- Knox Group, upper part, on north flank posure of southward dipping, Middle of Parks Mill anticline. Ordovician rocks in a fault-bounded, Crossing axial trace of Park Mill anti- graben-like structure. cline. Base of Athens Formation. Turn right onto State Road 708. Turn right onto gravel road, State Road Sharp left curve. 664,to South Holston Lake. On left are overturned beds of Lenoir- Road junction at right with State Road Mosheim limestones. 710,continue on 708. Roadcut on left in overturned Athens Bethel Elementary School on left. shale. Outcrops on both sides of road are in Outcrops in fields of Lenoir-Mosheim Knox Group, upper part dolomite and limestone with some conglomerate at Lesoir-Mosheim limestone. The dip is the base of the unit (~iddleOrdolvician south. unconforqity). To left, on hillslope, is Right roadcut has vertical beds of exposure of shale in the Athens Forma- Athens shale. tion which is in a synclipe. Thick-bedded conglomeratic sandstones Crossing xial trace ofi same spncline. on right have steep dip to the north- Holston I$ ountdin is on horizon ahead. west. Turn right onto State Road 722. The same conglomeratic sandstone unit has dip to southeast. The principal axis Karst topography on left in Chepultepec of the South Holston syncline lies limestone; solution weathering is en- between these two exposures. hanced by fractures along a thrust fault. Lenoir-Mosheim limestone on left road- Note the disappearing stream in pig pen. bank and on hillslope to right across To the right along creek are outcrops Bumgardner Branch. of Chepultepec limestone. STOP 7. From top of hill walk 50 yards Junction on right with State Road 710; to right (west)toward Bowman Branch. continue ahead on State Road 710. Trench in hemlock grove is an old iron Trace of an unnamed thrust fault inter- prospect pit in cherty dolomite of the sects road.