G. H. Williams — Peridotites near PeehsMll, W. Y. 



the northern half of Stony Point on the west side of the Hud- 

 son River, and to the southern portion of Montrose Point on 

 the east side of the river opposite Stony Point. Even here, 

 however, these rocks show a decided tendency to become feld- 

 spathic. 



1. Hornblende Pebidotite. 

 Hornblende Picrite (Bonney);* Hudsonite (Cohen). f 

 The best locality for specimens of this type of peridotite 

 is at King's Ferry, in the extreme northwest corner of Stony 



Point, a small prominence on 

 the west side of the Hudson, 

 somewhat S. "W. of Verplanck. 

 Across the western portion of 

 this point the New York, West 

 Shore and Buffalo Railroad have 

 recently made some long and 

 deep excavations which admira- 

 bly expose the chrysolite rocks, 

 together with their line of con- 

 tact with the mica-diorite on the 



north and with the mica-schist on the south. The road fol- 

 lows the shore across the northern area of soda-granite (mica- 



*Qt. Jour. Geol. Soc, xxxvii, 1881, p. 137. Bonney's name for this group of 

 rocks is not a good one. inasmuch as picrile, by the sanction of long usage, indi- 

 cates an aggregate of olivine and augite. Moreover Bonney considers the com- 

 pact brown hornblende to have originated from the paramorphism of augite, a 

 supposition which for the brown hornblende of the Cortlandt peridotites at least 

 is wholly untenable. 



f This rock resembles very much the well known " Schillerfels," occurring near 



