8 Geologic Maps, Geophysical Maps, Digital Geologic Maps, and Derivatives from Geologic and Geophysical Maps (Posters)

Thursday, 10 April 2014
8:00 AM - 12:00 PM
Latham A/B/C

A NEW GEOLOGIC MAP OF GERMANY VALLEY, PENDLETON COUNTY, WEST VIRGINIA, WITH CROSS SECTIONS AND REVISED STRUCTURAL AND STRATIGRAPHIC INTERPRETATIONS

Paper number: 8-12
Program: Theme Sessions
Time: 8:00 AM – 12:00 PM

Authors

Abstract

A new geologic map of Germany Valley, a deeply eroded anticlinal valley developed along a culmination of the northeast-trending Wills Mountain Anticlinorium, is presented. The valley is underlain by a sequence of speleologically significant Ordovician carbonate rocks in which several major caves are present including Hellhole, the 7thlongest cave in the U.S. with > 40 miles (64 km) of known passage. The Wills Mountain Anticlinorium is the westernmost fold of the Valley and Ridge province in this area, and it can be traced for nearly 200 miles (320 km), from western Virginia northward into Pennsylvania. Prior maps (the most recent being by William J. Perry in 1971) showed Germany Valley as an asymmetrical, northeast plunging anticline, with a moderately dipping southeast limb, a nearly vertical to overturned northwest limb, with faulting restricted to siliciclastics (Juniata and Tuscarora Formations) along the northwest limb. Our mapping has revealed that the structure of this valley is more complex than was shown on any prior maps, and the older Ordovician carbonates are also faulted. Deformation at all observable scales in these carbonates including fault gouge strain indicators and outcrop-scale folding of bedding collectively suggests east over west, brittle zone deformation. A flexural slip faulting model synchronous with formation of the Wills Mountain Anticlinorium is suggested for numerous bedding parallel faults. A map scale fault inferred by juxtaposed stratigraphic units is hypothesized to be the result of a local buttressing fault block or fault horse at depth that likely occurred prior to the bedding parallel faulting.

Stratigraphically, a dark gray limestone underlying the New Market Limestone in some stream valleys and which was not recognized on any prior maps is tentatively identified as the upper Row Park Limestone, pending additional study, as it could be Beekmantown. Above the New Market the Big Valley Formation includes the Lincolnshire, Ward Cove, Peery, and Benbolt Limestones of prior workers, but we have determined that in this area the Big Valley is best used only for the lower three units undivided, as the Benbolt can be recognized and mapped separately in many areas. Carbonate units above the Benbolt are the McGlone, McGraw, and Nealmont Limestones, and the Dolly Ridge and Reedsville Formations.