and the Northern part of New York Island. 433 
interrupted over more or less of the interval between, by the 
s 
eiss, 
The schists west of this line of limestone show themselves promi- 
nently on New York Island east of 4th Avenue between 129th 
and 130th Streets, and also both west and east farther south 
between 125th and 114th Streets. The beds have, in general, 
a dip of 60° to 50°. But there are broad and narrow undula- 
tions, with eastward and westward dips, as represented on the’ 
map, and illustrated as to general character in figs. 82, 33. 
Some portions are /fibrolitic, as stated above; and this fact, 
taken in connection with the existence of the related cyanitic 
schist in the same line of bedding or strike near 42d and 45th 
Streets, is much in favor of the conclusion that this western 
overlying stratum of schist continues southward at least to 42d 
Street, or the vicinity of the Grand Central Station; and the 
fact that limestone exists in the same line of strike in 50th 
Street sustains this conclusion. 
2. LIMESTONE ARRA, Nac, 
A. In Westchester County.—The limestone area No. 2, or that 
of the valley of Cromwell’s Creek (called also the Clove) joins 
that already described through the region of Fleetwood Park, 
as shown on the map. The northern limit of the belt is about 
two miles north of McComb’s (or Central) Bridge. At this north 
farther north the schist makes only its western portion for 600 
yards, and then narrows out leaving limestone alone, excepting 
an occasional intercalation of gneiss; and it is the kind o 
limestone already spoken of as firm and gneiss-like in aspect, 
and as containing much mica and in places green coccolite. 
From the ridge, the limestone extends across Cromwell Creek 
Valley: but it is here much less firm, and has in general small 
and varying dip. The beds are well displayed just east of 
entral Avenue a mile north of McComb’s bridge (near Judge 
Smith’s House) where the layers dip eastward from 30° to 70° 
and some are remarkably cbloritic; and also less satisfactorily, 
half a mile farther north (opposite Sibbern’s Club House, ©.). 
Limestone of the firm thick-bedded kind is exposed to view also 
on the rising land east of the lower part of Cromwell's Creek 
and, at one place, in sight from the east end of the 161st Street 
bridge (the first north of MeComb’s), it has been quarried. 
