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ANNALS NEW YORK ACADEMY OF SCIENCES 
Summary 
A detailed study of all available data bearing upon the question of areal 
and structural geology of the covered portion of southern Manhattan Island 
leads to the following general conclusions: 
1. All of the typical crystalline rock formations are found within the 
area. 
2. Manhattan Schist forms the rock-floor from the Bowery westward to 
the Hudson. 
3. Between the Bowery and the East River there are at least two ' 
belts of Fordham Gneiss, three belts of Inwood Limestone and 
one other belt of Manhattan Schist. 
4. The structure is essentially closely compressed and slightly overturned 
folds accompanied by some thrust-faulting and a tendency to the 
development of weak crush zones along the chief planes of movement. 
5. The East River, in its great eastward bend around the Lower East 
Side, is displaced from its pre-Glacial channel by Glacial drift 
and now flows across perfectly sound rock at a much greater elevation 
than the channel it once occupied. 
It appears therefore that, so far as southern Manhattan is concerned, 
the present river channels are not controlled by limestone belts, as usually 
assumed, but the East River is controlled by its drift obstruction. 
It will be apparent at once that the configuration of the rock floor is now 
subject to as extensive revision as the other geologic features. 
Areal Map and Geologic Cross Section 
The accompanying map and cross section are an attempt to represent 
these features and are intended to serve as the basis of further correction 
of the areal and structural detail of southern Manhattan. Neither the 
map nor the cross section can be considered accurate for depth or dip of 
formation or exact position of contact, but they are the best interpretation 
the writer can make of the data now known. Both are presented in the 
belief that the general features and structures as given will serve a useful 
purpose in guiding explorations for rock floor and rock condition in the area 
covered. 
