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ANNALS NEW YORK ACADEMY OF SCIENCES 
is certain that this formation also occurs. In that case the Inwood should 
also be found between the other two. The lack of data at first, except along 
the water front, made it impossible to draw more than very general lines. 
Drawn in this way, of course, the lines are too regular and straight, but it is 
certain that they indicate more nearly the actual existing areal distribution 
of formations than any of the maps now in use. 
A southward extension of the Blackwell’s Island anticlinal belt of Ford- 
ham Gneiss reaches across the East River in a long narrow strip toward the 
Manhattan tower of Brooklyn Bridge. How much of this anticlinal fold 
would actually expose the Fordham, if the drift were scraped off, it is impos¬ 
sible to say, but it is certain that this formation exists there. Inwood Lime¬ 
stone must be accounted for, unless faulted out, on the west side of this 
belt, and then the Manhattan Schist occupies the area westward to the 
Hudson River. 
On the east side of this Fordham anticline, a parallel belt of Manhattan 
Schist and associated Inwood Limestone is to be expected, as indicated on 
the map, and this is succeeded by Fordham Gneiss which occupies the 
eastern border of the island in the district known as the “Lower East Side.” 
Explorations made some years ago along the line of the gas tunnel 1 
across the East River at Seventieth Street indicate comparatively narrow belts 
of limestone there in both the east and west channels. Their limited width, 
together with the accompanying strongly developed disintegration zones, 
indicates rather extensive squeezing out and faulting of this formation along 
planes parallel to the strike. Such movements, of course, are capable of 
entirely cutting out the intermediate limestone from between the schist 
and gneiss. How much of this condition exists in the continuation of these 
zones southward through Manhattan, it is impossible at present to say. 
The intermediate belt is indicated on the map as a continuous schist- 
limestone area, and at one point, at least, the limestone is known to occur, 
namely, on the southeastern margin of the Manhattan pier of the Manhattan 
Bridge (Bridge No. 3) at the Foot of Pike Street, where it w T as penetrated 
by a drill in exploring for the bridge site. It is not probable, however, that 
there are continuous limestone belts of any considerable areal importance, 
else the East River would have been able to follow them and could thereby 
have taken a more direct course than it now does. At any rate, there is a 
probability of finding three belts of limestone, unless they are cut out by 
faulting. 
On the Brooklyn side, no formation of the series except the Fordham 
and its associated igneous masses, such as the Ravenswood granodiorite, 
1 J. F. Kemp: The Geological Section of the East River at Seventieth Street, New York, 
Trans. N. Y. Acad. Sci., Vol. xiv, p. ,273. 1895. 
