432 J. D. Dana—On Southern Westchester County 
dip 60° W. But farther south in the same line, that is, east 
of 3d Avenue, there are large outcrops of micaceous gneiss 
between 89th and 70th Streets, having the strike of the bedding 
N. 30° E. The beds are undulating, pitching at small angles 
both eastward and westward, except east of Avenue A toward 
or near Kast River, where the dips become high—90° to 70° E. 
Fig. 32 represents a section on 75th Street, east of Avenue A; 
fig. 88, another on 77th Street, east of the same avenue; fig. 
34, a portion of a section near Hast River. 
* ey thus accord in position with the similarly 
ob situated beds north of the Harlem, and would seem 
Wit} to indicate that the anticlinal is distinguishable at 
\ | least to this distance, although it is hardly probable 
tha tinues so far down the river. 
The western or Mott Haven Limestone band outcrops on the 
island between 118th and 124th Streets. The ledge of lime- 
stone with intercalated gneiss, north of 122d Street and east of 
and adjoining Lexington Avenue, first described by Mr. 
Stevens,* is the principal locality remaining. It is about 125 
feet in breadth. His section of the limestone and schist con- 
tains an anticlinal flexure (now hardly distinct); but the mass 
exposed is certainly but a small part of the whole limestone 
band, and the flexure is evidently one of the local flexures so 
common in the stratification of that vicinity. The easternmost 
of the beds on 122d Street—which is about 35 feet wide and the 
purest—bends from N. 28° E. (the normal strike) to N. 54° E., 
and disappears beneath the adjoining yard and house; and 
probably the chief part of the limestone band is situated farther 
to the east along 3d Avenue. There are also three layers of 
limestone in the schist south of 122d Street. Besides these 
outcrops, there is much calcareous material in portions of the 
gneiss east of 4th Avenue between 118th and 120th Streets, as 
reported by Dr. Gale, and also on 124th Street, which localities 
lie to the west of the general range of the band. : 
As to the southern limit of the band there is no positive 
evidence. In view of the range of low land directly south 
along and east of 8d Avenue, and the outcrops of schist on the 
western side, it probably goes at least as far as 103d Street. 
Mr. R. P. Stevens, in the paper already referred to, states that 
limestone was found 18 feet below the surface, in 50th Street, 
between 3d and 4th Avenues, in excavating for a culvert; an 
this must belong to the same band, althongh the limestone 1s 
* Annals of Lye. Nat. Hist. of N. York, viii, 116, 1865. 
