DescriptionBlack mudshale with glacial scratches 3 (27243862958).jpg
(~3.65 centimeters across at its widest)
This specimen is a clast from an anthropogenically-disturbed glacial deposit at a petroleum wellsite in east-central Ohio. The rock itself is a black mudshale derived from the Ohio Shale, a thick Upper Devonian unit representing deposition in a moderately deep, anoxic seafloor environment. It was eroded from an outcrop during the Pleistocene by a continental glacier (the near-southernmost Laurentide Ice Sheet), then deposited as the glacier moved or melted away.
Under low-angle lighting, numerous thin scratches are evident - these are glacial striations, formed by gravel abrading gravel within the moving glacial ice. (There is a possibility that the scratches are partially or entirely anthropogenic, formed by bulldozer disturbances of the deposit as the wellsite was being prepared. Shale is a soft rock. However, I suspect the scratches are glacial in origin.)
Locality: VanWinkle Unit # 1 wellsite (permit # 34089261880000) (804' SL, 1794' EL, northeastern quarter of township), west of Granville, St. Albans Township, Licking County, east-central Ohio, USA (40° 04' 55.13" North latitude, 82° 34' 38.00" West longitude)
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