Trenton Group and Black River Group, undivided

Trenton Group: dark, crystalline, nodular, and argillaceous limestones, with some metabentonite streaks. Includes the Nealmont, Oranda, Edinburg, and the upper part of the Chambersburg Limestones of northeastern West Virginia; also the Moccasin and Eggleston Formation of Mercer and Monroe Counties. Black River Group: predominantly gray aphanitic limestones, with many bioclastic streaks; siliceous in the lower part.
State West Virginia
Name Trenton Group and Black River Group, undivided
Geologic age Ordovician
Lithologic constituents
Major
Sedimentary > Carbonate > LimestoneTrenton Group: dark, crystalline, nodular, and argillaceous limestones. Black River Group: predominantly gray aphanitic limestones, with many bioclastic streaks; siliceous in the lower part.
Incidental
Sedimentary > Clastic > Mudstone > Claystone > BentoniteTrenton Group: with some metabentonite streaks
Comments Printed map has no indiviual description for this unit and no name, but has individual symbol and color. Only uses brackets to combine Ot and Obr. Otbr is used in digital map, so combined Ot and Obr together and called this the "Trenton Group and Black River Group, undivided". Combined thickness: Northeastern 470-1010 ft, Western 890 ft, Southeastern 665 ft.
References

Cardwell, D.H., Erwin, R.B., and Woodward, H.P., 1968 (slightly revised 1986), Geologic Map of West Virginia: West Virginia Geological and Economic Survey, Map 1, East Sheet, scale 1:250,000.

NGMDB product
Counties Berkeley - Jefferson - Mercer - Monroe