Black River Group (NYObr;2)

State	New York
Name	Black River Group
Geologic age	Middle Ordovician
Original map label	Obr
Comments	part of Lorraine, Trenton, and Black River Groups up to 4500 ft. (1400 m).
Primary rock type	limestone
Secondary rock type	dolostone (dolomite)
Other rock types	chert
Lithologic constituents	Major Sedimentary > Carbonate > Limestone Minor Sedimentary > Chemical > Chert Sedimentary > Carbonate > Dolostone
Map references	NYS Museum, NYS Geological Survey, NYS Museum Technology Center, 1999, 1:250,000 Bedrock geology of NYS, data is distributed in ARC/INFOr EXPORT format (with ".e00" extension) in 5 seperate files based on printed map sheets, http://www.nysm.nysed.gov/gis.html. [http://www.nysm.nysed.gov/gis.html.]
Unit references	D. W. Fisher; Y. W. Isachsen, L. V. Rickard, 1970, Geologic Map of New York State, consisting of 5 sheets: Niagara, Finger Lakes, Hudson-Mohawk, Adirondack, and Lower Hudson, New York State Museum and Science Service, Map and Chart Series No. 15, scale 1:250000.