etapa AT tanya aaa, ay era a Rane eo eae ne aD ar ee tae 
talks E (et eee TR 
and the Northern part of New York Island. 439 
These statements make it manifest that the question as to 
the actual character of the flexures is not easily cleared of the 
doubts that arise from local displacements and from varying 
positions of the axial plane of the flexures. Uncertainties 
exist also because of the covering of soil or drift over a large 
part of the region. 
Although the plotting of sections from the obtainable facts 
(exhibited on the map) is consequently unsatisfactory work, I 
present the following sections (see page 441) as probably, in a 
general way, correct. The four sections cross the region from 
west (the left) to east: No. 1, through Tremont; 2, through 
Morrisania, along 168th Street, just north of Fleetwood Park; 3, 
through Melrose, along 159th Street; 4, through Mott Haven, 
along 138th Street. A section through Harlem would differ 
little from the last. 
it may correspond to otsdam sandstone and the schist 
associated with it in some regions (as near Peekskill and 
ompkins’ Cove). Its veins are mostly of quartz. The syn- 
comes covered with schist — overlying schist—south of 
Eden, as appears in section 2, and this ridge extends south to 
Mott Haven, appearing in sections 3 and 4, and beyond. It 
is in places fibrolitic to the north of Mott Haven, as well as to 
the south. 
Whether the schist between Cromwell’s Creek and the Har- 
lem River limestone is in one, two, or more folds is uncertain ; 
ifin only one, the actual thickness of this underlying stratum 
of schist is large, and only a small lower portion of it is con- 
tained in the belt of schist west of Tremont. 
The two westernmost bands of limestone in section 1 are 
those of Area No. 3,—the eastern or Harlem River band, and 
the western or King’s Bridge Road band. They are represented 
as the opposite sides of a synclinal with overlying schist between. 
In the other sections only the eastern of the two occurs. i 
schist is mostly micaceous gneiss and mica schist, all the way 
to 110th Street, but contains in some parts hornblende schist. 
* The local flexures in the beds are intended to show only that there are local 
_ flexures, not to represent special flexures. 
