Limestone Belts of Westchester County, New York. 31 
serpentine and other hydrous silicates originated from minerals 
that are common in the Westchester County limestone (dolo- 
mite) beds, and that this change has taken place in many beds 
that are still chiefly limestone, gives it support. The following 
are some examples under the last point: 
e hydrous anthophyllite (first known from New York 
Island) was long since shown to be altered tremolite, the most 
common of the limestone minerals; and limestone has often 
been observed in close association with this hydrous mineral, or 
as the adjoining or containing rock. At the most important 
locality—between 57th and 68d streets on the western side of 
New York Island—Dr. Gale describes it as associated with 
serpentine and limestone. 
eral, actinolite, under the same conditions. Some of the’ sil- 
icates are changed also to tale, making pearly plates distributed 
tparingly through the serpentine. The dolomite has also par- 
county, and, were it not for the tremolite and dolomite, would 
Suggest other relations for the beds. 
any disseminated grains and masses of serpentine in the 
New Rochelle serpentine have the yellow and brownish yellow 
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