12 A GEOLOGICAL HISTORY. 



in the cells were found small crystals of Quartz, 

 Feldspar and Prismatic Mica ; the Gneiss lying 

 superincumbent, with its dip varying from 30° to 45°. 



2nd Sienite. — (See Map and Section, plate \,fig* 

 \ fy'l, marked 2.) This crops out at the north edge 

 of the Serpentine : it may possibly be a large 

 boulder of Greenstone, but if it proves so, it is 

 the largest on the island ; it is buried within a few 

 feet of its top, which presents a considerable 

 surface ; it contains more Quartz than any of the 

 Greenstone of the palisades which I have seen, 

 and is a rock almost entirely composed of Quartz 

 and Hornblende. 



3d Serpentine. — {See Map and Section, plate 

 ^fiS' * 4* %, marked 6.) Between 54th and 62nd 

 Streets, the shore and 10th Avenue, there are 4 or 

 more small knolls, of black Serpentine, with scales 

 of silvery and golden Talc, accompanied by a vein, 

 about 12 feet wide of Anthophyllite. This vein is 

 in a vertical position. At the north end of the 

 Serpentine proper, this Anthophyllite shows itself 

 in two places, in place; one, on the rising 

 ground, and near the Sienite, the other at high- 

 water mark on the shore. Actinolite is found im- 

 bedded in the Anthophyllite. The Serpentine 

 locality commences where the Granite ends. At 

 the south end, there is a vein of Carbonate of Lime. 



