Bedford Gneiss (NYOb;3)

State	New York
Name	Bedford Gneiss
Geologic age	Ordovician?
Original map label	Ob
Comments	part of Eugeosynclinal (Allochthonous) Sequence up to 4000 ? ft. (1200 m). On printed map, unit has ? in front of Ob. Secondary unit description from USGS Geologic Names lexicon (ref. NY046): Named the Bedford "augen" gneiss for village of Bedford, Westchester Co., NY. Unit is an "augen" gneiss associated with the Manhattan schist southeast and south of Bedford. The "augen" structure is developed in two types of rock, a mica schist and a hornblende schist, but entire area does not have the "augen" structure. It appears in bands usually parallel to the foliation. The bands grade into the ordinary schist by gradual disappearance of the "augen," which sometimes stops suddenly and at other times drops out gradually. Age is not stated.
Primary rock type	gneiss
Secondary rock type	amphibolite
Other rock types	augen gneiss
Lithologic constituents	Major Metamorphic > Amphibolite Metamorphic > Gneiss > Biotite-gneissbiotite-quartz-plagioclase gneiss; in part with augen of andesine and microcline
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. USGS Geologic Names Lexicon (GEOLEX) [http://ngmdb.usgs.gov/Geolex/]
Geographic coverage	Westchester