BSE ey Loe RNS ne ee ae aN ER a, EE CA Nt a eS mE MET 
‘ ye Sena Stee sige 
and the Northern part of New York Island. 437 
described above. On Harlem River about a mile north of this 
bridge (or 14 mile south of King’s Bridge), at Morris Dock 
Station, a light gray, fine-grained gneiss outcrops, which effer- 
vesces on the application of acid on account of the presence of 
calcareous or dolomitic material. This characteristic appears 
to show that it lies near the eastern border of the Harlem 
River limestone. North of this, to King’s Bridge, there are no 
tinues to Central Park, the dip being generally 85° 
E. 
° 
4. STRATIGRAPHICAL RELATIONS OF THE LIMESTONE AND SCHIST OF THE 
DIFFERENT AREAS. 
Mutual relations of the limestones—From the statement of 
facts which has been made and the exhibition of them on the 
map, it is evident that the limestone of area No. 1 and that of 
o. 2 are one and the same mass or formation. 
As to the identity with these of the limestone of the western 
area, No. 8, the proof is less positive, since No. 2 is nowhere 
oa eth de 
River at McComb’s bridge, because of the varying flexures 
and low dips in the stratification just north of it (much like 
map) and the contrast in this respect with the beds just south 
of the bridge. But after a careful study of the beds of both 
the 8th, so low that grading for streets has been carried on by 
filling, not by excavation, and no rocks in place have been 
encountered. Such features are of the kind natural to a lime- 
stone area, and suggest that a union of the limestone bands of 
the 8th and 6th avenues may take place somewhere between 
135th and 120th Streets. 
