362 J. D. Dana— Geological Relations of the 
= farther north on the Morrisania side, the anticlinal is a 
more gentle one. The limestone here extends over half a mile 
west of the railroad, the western limit being nearly half way 
up the slope that makes the high western side of the park. 
Area 2.—The second belt, or that of “the Clove,” Bridge 
Cromwell’s Creek, north of Central (or McComb’s Da am) B 
and the brook emptying into it. The most southern pate 
occurs about a mile north of the aes mei the crossing 
of the brook by Central avenue. Some of the layers at this 
place contain much chlorite in bright ¢ green scales. It out- 
crops again near the ‘Club House.” North of this the acrte 
ence of limestone is indicated only by the form and definite 
ness of the valley and by the outcropping schist on its sidek 
The limestone varies much in strike, owing to contortions, but 
the adjoining schist gives for the strike about N. 25° E. 
This belt probably continues southward into New York 
Island, as R. P. Stevens has observed,” who says that in grading 
east of 6th avenue in 132d street, limestone was cut t rough. 
Area 3.—This limestone belt is a prominent feature of the 
north a of New York Island. From the island it extends 
three miles northward into Westchester County, along Tibbit’s 
Brook. At Kingsbridge a deep cut is made through it for the 
Hudson River railroad. North of this place it is not in sight 
along Van Cortland’s Lake, but outcrops at points in the val- 
ley of Tibbit’s Brook above this to if not beyond the stone- 
arched bridge, nearly three miles from Kingsbridge. Crumb- 
ling masses of the limestone lie on the eastern approach to 
this bridge which, as I am informed by the superintendent 
in its construction, Mr. John Wetherill, were quarried in that 
vicinity, his letter saying hee opened several quarries for 
stone for the bridge,” and found “all the rock of the valley to 
be limestone of a poor kind.” The mica schist on the east 
ie 
a N. 37°-40° E., the ip in both 70°-75° to the eastward. 
he limestone area from dae. southward was imper- 
fectly mapped by Dr. L. D. Gale.” South of the Harlem, it 
widens on its eastern side for the first mile and just north of 
the east-and-west inlet called Sherman’s Creek, extends from 
a point west of the “ Kingsbridge road” or Inwood street to 
the Harlem River. Thence its western side has a narrow 
continuation southward along the Kingsbridge road in a well- 
defined valley wall-sided on the west, while its broad middle 
portion is fronted, south of Sherman ‘Creek, by hills of mica- 
ceous gneiss; and it is probable, judging from its strike, that 
19 Annals Lye. Nat. Hist. New eo viii, 116. 
20 In Mather’s N. Y. Geol. Rep., Plate I. - 
