History of the Geology of JVew %York Island. Ill 



hundred feet west of Tenth Avenue, the rock is entirely changed, both 

 in composition and structure. In composition, it is a mixture of lime- 

 stone and serpentine ; -while in structure it is destitute of strata, and 

 lies in beds. 



" AnthophyUite locality — This rock extends from W. 59th st. to 63d 

 st., its strike is N. 30° E. At 63d st. it is talcose in structure, and may 

 be split into thin slabs ; in others it is dark grey, almost black, composed 

 of straight fibres arranged in a columnar form, meeting and crossing 

 each other frequently at right angles. 



Drift Stria;.— These vary from N. 25° W. to N. 48° W., depth of 

 striae from a few lines to oue and a half inches. 



"From W. 195th st. to 197th st., there is an opening through the 

 western ridge, forming a continuous valley from the Hudson to the 

 Spuyten-Duyvel creek. Through this valley, vast masses of drifts have 

 been carried and piled u$> in conical hills east of the road, and on the 

 northern slope of the eastern ridge." 



In 1810, Prof. H. D. Rogers, corresponding member of the 

 Lyceum, in his Geological Report of the State of New Jersey, 

 describes the gneiss of the seaboard rocks as appearing at 

 Trenton and Jersey City, N. J., on Staten Island and Manhat- 

 tan. He was the first to draw a distinction between the gneiss 

 of the Atlantic and the Highlands — the former having mica, 

 talc, chlorite, and other laminated minerals of the micaceous 

 order as prominent ingredients, thereby differing from the 

 latter. 



In 1813, Mr. "W. W. Mather, to whom was committed the 

 geological examination of the First District of the State of New 

 York, brought out his final report, in the fourth volume of the 

 Natural History of New York, accompanied by a geologi- 

 cal and topographical map of the Island of Manhattan. His 

 brief description is as follows : 



" The Island of New York is underlaid by rocks of gneiss, mica- 

 ceous gneiss, hornblendic gneiss, hornblendic slate, hornblendic rock, 

 limestone, the anthophyllite rock, and granite. The micaceous gneiss is 

 the prevailing rock. The strata are nearly vertical, some dipping east- 



