Bedford Gneiss

Biotite-quartz-plagioclase gneiss and interlayered amphibolite; in part with augen of andesine and microcline.
State New York
Name Bedford Gneiss
Geologic age Ordovician?
Lithologic constituents
Major
Metamorphic > Amphibolite
Metamorphic > Gneiss > Biotite-gneissbiotite-quartz-plagioclase gneiss; in part with augen of andesine and microcline
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.
References

Fisher, D.W., Isachsen, Y.W., and Rickard, L.V., 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 1:250,000.

USGS Geologic Names lexicon found at: http://ngmdb.usgs.gov/Geolex/

https://ngmdb.usgs.gov/Geolex/search

NGMDB product
Counties Westchester