History of the Geology of New York Ida/id. 117 



This fold of limestone has been cut through at the " Mon- 

 tauk Steel "Works" on the main land at Mott Haven. Its base 

 is one hundred feet wide, and the height is about twenty feet. 

 The thrust of large masses of limestone into the solid gneiss 

 was seen, crushing and grinding the latter as it passed, -bowing 

 that the rocks were hardened when the folding action took 

 place, and the thrust was made. 



At Melrose, on the mainland, there is another bed of lime- 

 stone which is traceable to Harlem River. This bed, traced 

 under the strait separating Barn and Randall's Islands from 

 New York, would explain the westward dip of the gneiss 

 along East River, and the eastern dip of the same rock on the 

 small islands of Hurlgate, and also the location of limestone 

 formerly to be seen at Corlear's Ho<>k, Avenue A or B. 



The fracture of this fold, and its subsequent abrasion, has 

 caused the channel now filled in part with the waters of East 

 River. 



Upon the mainland in Westchester Co., at Hastings, is 

 another bed of marble, which, continued southwards, would 

 underlie the Hudson River. Reasoning by analogy, we infer 

 that this is the case, for in no other way can we account for the 

 beds of limestone at Hoboken ; we have, therefore, in our sec- 

 tion of the rocks across from N. J. to Randall's Island, so 

 placed it. We have good geological reason for inferring that 

 the North River flows through similar fractures and abrasions 

 of folds of gneiss and limestone from Haverstraw Bay to the 

 Narrows. 



Our section is a constructed one, and therefore in part arti- 

 ficial, but if a section had been made from Kingsbridge marble 

 directly eastwards, across Westchester Co., all the beds of lime- 

 stone would have been found in precisely similar conditions and 

 geological positions, and which are the northward continuations 

 of those upon our island. 



In addition to the foldings of the strata in a longitudinal 

 direction, -there are other disturbances of strata, which will 



