Limestone Belts of Westchester County, N. Y. 363 
the eastern side has its narrow continuation down Harlem 
River, as is suggested on the map, although no outcrops appear 
to prove it. If this be the correct view, the area as a whole 
resembles in form the Tremont or No. 1, and, like that, owes 
the forked character to its being the remains of a denuded fold. 
The most southerly ee of the limestone on the Kingsbridge 
road is, as found by Dr. Gale, near 204th street, or about 500 
yards south of poke: street, where the width of the valley is 
nearly 800 yards. The valley fades out and is closed by the 
— at 182d street; the limestone may exist beneath as far 
s 190th street, if not beyond. 
The supposed. Harlem River or eastern fork of the belt has 
western side. The depression is well defined to 115th street, 
and is distinct to 110th.” 
ver the more southern part of New York Island, in the 
line of the western fork of the belt, there are some localities 
” occur in the 
tions the occurrence of black serpentine between 10th avenue 
and the river and between 54th and 62d street, ae a bed twelve 
feet wide containing also limestone and tale. At 157th street, 
100 feet west of 10th avenue, a mixture of Hea and ser- 
pentine has been observed. 
North of Area No. 1, which stops at Fordham, the line of out- 
cropping limestone is shifted a little eastward to the course of 
the valley of the Bronx, in which occur, at intervals, the areas 
numbered 4, 10 and 11; and from No. 3, there is a shift west- 
ward, to the course of ce valley of Saw Mill River, along 
which there are, at Yonkers, two small parallel areas 7 and 
and farther to the north, numbers 14 and 15. The line of No. 
may perhaps fo represented in No. 9, which follows the 
course of Grassy Sprain Brook. To the east are two areas, 
nearly in the same line of strike, numbered 5 =e 6, which are 
the serpentine areas of New Rochelle and 
*! Whether the fold in this limestone is a synclinal or pieces a do not 
Positively decide. This point will be further considered in the appendix 
* Mather’s N, Y. Geol. Report, p. 582. 
