Stratigraphic Notes, 1994 U.S. GEOLOGICAL SURVEY BULLETIN 2135 U.S. GEOI_OCTCAL SURVEY RESTON, VA. NOV 2 0 1995 SR LI -, ~ ._t.._.•,~- ll ·~• • I \ a..11~ - ...... SIJJtVEY ,. ... ·... '·;'• -~,1111. L~I l• • I I hquakics & ' rH ers) ca n he oht a l ro rn the Sern th St ate St. Superintendent of Documents SPOKANE, Washington­ Go"'· ernment Printing Office West 904 Ri ve rside Ave. Washington, DC 20402 • WASHINGTON, D.C.- Main Interior B l~Jg. ( Check or money orJcr must he pay ah le to Superintendent of and C Sts. , NW Document s.) Maps Only Maps Maps may he purchased over the counter at the following U.S . Geol@g ical Survey offices: For maps. address mai I orders to U.S. Geological Survey, Information Services • ROLLA, Missouri- l 4C, Indcpcn~lcncc Rd . Box 25286, Federal Center. Denver, CO 80225 • STENNIS SPACE CE TER, Mississippi- Bl og. Stratigraphic Notes, 1994 U.S. GEOLOGICAL SURVEY BULLETIN 2135 Three short papers present changes in stratigraphic• nomenclature in Virginia, Kentucky, and Alaska UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1995 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY GORDON P. EATON, Director For sale by U.S. Geological Survey, Information Services Box 25286, Federal Center, Denver, CO 80225 Any use of trade. product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government. Published in the Eastern Region, Reston, Va. Manuscript approved for publication April 12,1995. Stratigraphic Notes, 1994 ISSN 1071-7102 CONTENTS Note Page 1. Middle Ordovician Stickley Run Member (New Name) of the Martinsburg Formation, Shenandoah Valley, Northern Virginia By Jack B. Epstein. Randall C. Orndorlf, and Eugene K. Rader 1 2. Middle Pennsylvanian Arnett Member (New Name) of the Breathitt Formation, Eastern Kentucky By Charles L. Rice 15 3. The Coast Mountains Complex of Southeastern Alaska and Adjacent Regions By David A. Brew. Arthur B. Ford, Glen R. Himmelberg, and James L. Drinkwater 21 III [V CONTENTS CONVERSION FACTORS Multiply By To obtain inch (in.) 2.54 centimeter foot (ft) 0.3048 meter mile (mi) 1.609 kilometer centimeter (cm) 0.3937 inch meter (m) 3.281 foot kilometer (km) 0.6214 mile 1. Middle Ordovician Stickley Run Member (New Name) of the Martinsburg Formation, Shenandoah Valley, Northern Virginia By Jack B. Epstein,' Randall C. Orndorff,1 and Eugene K. Rader' ABSTRACT and underlie shale and graywacke of the Martinsburg For- mation in the Shenandoah Valley of northern Virginia Dark-gray, laminated to thin-bedded shaly limestone (fig. 1). In ascending order, the Middle Ordovician carbon- and calcareous shale and siltstone, previously identified ate rocks consist of the New Market Limestone (light-gray, as either the Oranda Formation or the lower part of the very fine grained limestone), the Lincolnshire Limestone Martinsburg Formation in Virginia and West Virginia, are (dark-gray, cherty limestone), and the Edinburg Formation herein revised as the Stickley Run Member (new name) of (irregularly bedded and knobby limestone and calcareous the Martinsburg Formation. Knobby limestone that was shale). Butts (1940) identified the limestones immediately assigned to the lower part of the Oranda Formation is now beneath the Martinsburg as the Chambersburg Limestone placed in the underlying Edinburg Formation. The type sec- (fig. 2). Later, approximately 50 ft of calcareous shale and tion for the Stickley Run is along U.S. Highway 11, 2.5 mi northeast of Strasburg, Va., where the lowest 140 ft are siltstone, shaly limestone, and scattered thin beds of meta- exposed. Cross sections indicate that the thickness of the bentonite immediately underlying the Martinsburg were Stickley Run is between 610 and 900 ft in Frederick and named the Oranda Formation by Cooper and Cooper (1946) Shenandoah Counties, Va. It is recognised on both limbs of and mapped as such by many subsequent workers. Cooper the Massanutten synclinorium, thinning to about 100 ft at and Cooper (1946) also changed the Chambersburg Lime- the south end of the synclinorium. The member is also stone to the Edinburg Formation and changed the underly- present for many miles north of the Virginia-West Virginia ing Lenoir Limestone to the Lincolnshire Limestone. A border, a total distance that probably exceeds 150 mi. The lithofacies similar to that of the Oranda is repeated lower lower contact of the Stickle), Run Member is defined as the within the Edinburg Formation (the Liberty Hall facies of base of the lowest calcareous shale or siltstone or shaly Cooper and Cooper, 1946). The original definition of the limestone above thicker bedded, knobby-weathering, Oranda was based primarily on the occurrence of the medium-gray limestone of the Edinburg, Formation. The Reuschella "edsoni-fauna. Platy shaly limestone and cal- upper contact is placed at the top of the uppermost platy careous shale that overlie the Oranda were placed in the limestone bed, generally about 2 in. thick, underlying non- lower part of the Martinsburg by Cooper and Cooper (1946) calcareous to slightly calcareous shales and graywacke of the overlying Martinsburg Formation. The age of the and subsequent workers. Stickley Run Member is Middle Ordovician, as indicated by Recent mapping by the U.S. Geological Survey in the conodont age determinations of younger and older rocks. Winchester 30'x60' quadrangle and in the Strasburg, Va., area to the south and mapping by the Virginia Division of Mineral Resources south of Strasburg indicate that the Oranda of previous usage and the calcareous shale and platy INTRODUCTION limestone that have been placed in the lower part of the Martinsburg Formation compose a distinct mappable unit, Limestone, cherty limestone, and calcareous shale of herein named the Stickley Run Member of the Martinsburg Middle Ordovician age overlie dolomite and limestone of Formation. The type section is along the northbound lane of the Beekmantown Group (Lower and Middle Ordovician) U.S. Highway 11 immediately east of Cedar Creek and approximately 2.5 mi northeast of Strasburg. The member is named for Stickley Run, a tributary to Cedar Creek, 0.6 mi north of the type section. The overlying Martinsburg con- U.S. Geological Survey, Reston, VA 22092. sists of shale and graywacke and is not divided into mem- 2 Virginia Division of Mineral Resources, Charlottesville, VA 22903. bers in the area of this report. STRATIGRAPHIC NOTES, 1994 EXPLANATION Outcrop of the Stickley Run Member of the Martinsburg Formation MS Mississippian, Devonian, and Silurian rocks DS Devonian and Silurian rocks Area of map Om Martinsburg Formation (Upper and Middle shown in figure 3 Ordovician) OE Middle Ordovician through Lower Cambrian mainly carbonate rocks Lower Cambrian through Middle Proterozoic rocks Contact v---v- Thrust fault— Sawteeth on upper plate 0 10 20 MILES 1 I r r r r 0 10 20 30 KILOMETERS Figure 1. Generalized geologic map of the northern Shenandoah Valley of Virginia showing the outcrop of the Stickley Run Member of the Martinsburg Formation. STICKLEY RUN MEMBER OF THE MARTINSBURG FORMATION, NORTHERN VIRGINIA 3 Butts Cooper and Cooper This report FEET METERS (1940) (1946) 200 -50 Martinsburg Stickley Run • Formation Member Martinsburg (part) of the Formation Martinsburg (part) _.-• Formation (lower part) 100- r — 25 Oranda Formation >joI j 1 7: Chambersburg Edinburg Limestone Edinburg Formation Formation EXPLANATION Calcareous shale and shaly limestone— ...1 " Dots show siltstone beds A:=1fil 1:=1 C=30 Knobby-weathering limestone Limestone , Figure 2. History of nomenclature of the Middle Ordovician Stickley Run Member of the Martinsburg Formation and underlying rocks. The lower part of the Stickley Run is well exposed in the Martinsburg at the contact with the overlying Massanut- three localities in the Strasburg, Va., area: ten Sandstone, the thickness of the Martinsburg, including ( I ) the type section along U.S. Highway 11 (locality a in the Stickley Run Member as defined in this report, is deter- fig. 3), where the lowest 140 ft are exposed (fig. 4; mined to be between 4,600 and 6,500 ft, the higher figure table I ); probably being more accurate (Epstein, 1993). (2) along Virginia Highway 55, 0.4 mi northwest of U.S. Highway 11 in Strasburg (the type section of the Oranda Formation of Cooper and Cooper, 1946), where PREVIOUS USAGE OF THE EDINBURG, 215 ft are exposed (locality bin fig. 3); and ORANDA, AND MARTINSBURG (3) along Tumbling Run and U.S. Highway 11, 1.7 mi FORMATIONS southwest of Strasburg, where about 300 ft are exposed (locality c in fig. 3). The Martinsburg Formation was first used as a strati- The upper part of the Stickley Run is poorly exposed, and graphic name by Geiger and Keith in 1891, but no satisfac- descriptions are derived from scattered exposures exam- tory definition was given for the unit. The name was ined during mapping. derived from the town of Martinsburg, W. Va. They errone- The thickness of the entire Martinsburg Formation has ously believed that the shales at Martinsburg are the same as been estimated to he between 1,500 and 4,500 ft by rocks exposed in the Harpers Ferry, W. Va., area that were previous workers, with the most recent estimate being 2,800 later identified as the Harpers Shale by Keith (1894) and all ft (Rader and Read, 1989). These figures do not include subsequent workers. about 50 ft assigned to the Oranda Formation. Because of Darton (1892) first described the Martinsburg as con- complex folding in the Martinsburg, thickness