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438 J. D. Dana—On Southern Westchester County 
South of this flat country there is a sudden transition to 
eneissic hills—those of the Park; the limestone is absent. 
Nothing is seen of the 8th Avenue belt, or of that east of 6th 
Avenue. Whether the formation continues southward under- 
neath the schist or not is a problem for further investigation. 
Some facts that may have a bearing on this point are men- 
tioned on page 363 of the last volume of this Journal. 
Thickness of the limestone—The thickness of the limestone 
formation may be best derived from the northern part of Area 
No. 1, in Tremont. Since the beds stand nearly vertical, the 
thickness is about half the width, and therefore not far from 
50 feet. From the section at High Bridge over the Harlem, 
be thickness there may be 700 feet, but probably is not over 
0 , 
correct, then the schist adjoining the limestone on its west side 
lies in a synclinal fold; and the broad part of the Cromwell 
Creek limestone band, in the vicinity of Mount Eden, and for 
the half mile south, is in an anticlinal: a single anticlinal only, 
although so wide; for the limestone in its western half is in 
broad synclinal or anticlinal; probably the former, since west- 
erly dips prevail on the Harlem River or eastern side of the 
schist and easterly on that of the Hudson. 
But, on the other hand, the schists north of Tremont next 
west of limestone area No. 1, so generally dip eastward that it 
is a fair question whether the limestone of area No. 1 1s not In 
a synclinal instead of an anticlinal. Again, at the extremity of 
this ridge of schist on the north side of Fleetwood Park (see 
on the east, as if the schist 
of this belt was in an anti- 
clinal instead of synclinal. 
eastern end of this section.) 
the schists to the west of it, on the west side of Cromwell 
Creek, dip eastward; and this favors the idea of a synclinal for 
this limestone instead of an anticlinal. ; 
