366 J. D. Dana—Geological Relations of the 
b. Middle Section of the County. 
Areas 14 and 15.—In Saw Mill River valley—the same that 
has its limestone belts near Yonkers—a large limestone area 
commences, about two and a half miles north of Ashford. It 
widens much at East Tarrytown and continues northward to a 
near junction with the Pleasantville area, No. 15. The mean 
strike for its northern two-thirds is about N, 30° K. 
The Pleasantville area also is broad and sinuous in course. 
It terminates just north of the Chappaqua depot. The strike 
near Unionville is N. 24° E., and at Pleasantville (where there 
are large and valuable quarries) mostly N. 30°-40° HK. A 
small independent limestone area (No. 15a) occurs just east of 
the Pleasantville area. 
Areas 16 and 17.—The long known Sing Sing belt com- 
mences south of the depot on the Hudson and extends north- 
northeast nearly to the north boundary of the town of Ossin- 
ing; and it also branches eastward up a small valley toward 
the Camp Woods, a furcation which seems to indicate the ex- 
istence of an anticlinal fold with the axis dipping southward, 
which was made thus to furcate by denudation as in the case 
of the Tremont area, No. 1, the opposite direction of pitch in 
the axis making the difference in the direction of the furcation. 
No. 17 is a small area of contorted limestone giving nothing 
reliable as to strike or dip. 
Areas 18 and 19.—A small Croton limestone area, No. 18, 
exists half a mile east of the village, without distinguishable 
planes of bedding. Mica schist bounds it on the north; but it 
may extend in the opposite direction to the bay, where drift 
and alluvium conceal the rocks. 
uth of Croton River a narrow area, No. 19, extends from 
near a bridge northeast of the last, called Quaker Bridge, to 
the fureation of the river at Huntersville, about two miles, fol- 
lowing mostly the west side of the road. Its southern portion 
has a westward bend, with which the strike of the limestone 
corresponds. 
Areas 20, 21 and 22.—No. 20 is a very small area at Merritt’s 
Corners among contorted rocks, giving uncertain strike and 
dip. No. 21, to the northeast, on the east border of Croton 
Lake, may be the margin of a long belt following the course 
of that part of the lake, though such an inference is not sug- 
gested by the observed strike. No. 22 is another small area of 
contorted limestone near Bedford station on the Harlem rail- 
road. 
Area 23.—No. 238 lies to the east of the Pleasantville belt on 
the borders of New York and Connecticut, and follows the 
course of Byram River to its source in Byram Lake. It was 
first laid down on Percival’s geological map of Connecticut 
