Old Fields, Hardy Co., West Virginia, USA

Age: Paleozoic (252.17 - 541 Ma)

Lithology: Sedimentary rocks

Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. [154]

Age: Devonian (358.9 - 419.2 Ma)

Stratigraphic Name: Marcellus Formation; Needmore Shale

Description: Marcellus Formation (part of Millboro Shale): predominantly gray-black to black thinly laminated non-calcareous pyritic shale. Contains one or more thin-bedded limestones, including the Purcell Member of Pennsylvania. Needmore Shale (part of Onesquethaw ("Onondaga") Group): predominantly dark grey or green, calcitic, mostly non-fissile shale. Gives strong "kick" on gamma ray logs. Tioga Bentonite near the top. Includes the black Beaver Dam Shale Member. Grades westward into the Huntersville Chert. Not mappable at scale of this map. Included with Dmn.

Comments: Printed map has no indiviual description for this unit and no name, but has individual symbol and color. Only uses brackets to combine Dm and Needmore Shale. Dmn is used in digital map, so combined Dm and Needmore Shale together and called this the "Marcellus Formation and Needmore Shale, undivided". Combined thickness: Northeastern 275-1055 ft, Western 170 ft, Southeastern 100-300 ft

Lithology: Major:{shale}, Minor:{limestone,black shale}, Incidental:{bentonite}

Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052. [133]