194 NEW YORK STATE MUSEUM 



Occasionally mucli larger crystals are found. Microcline, fibro- 

 lite, cyanite and staurolite are also frequent accessories. The 

 Hudson schist has a marked schistosity, which is frequently, 

 though not always, nearly parallel to the bedding. 



The aspect of this formation is intimately affected by numer- 

 ous igneous intrusions and injections of granitic and basic 

 material, which in some places are so numerous as to predomi- 

 nate over the schist. The small masses are, for the most part, 

 parallel to the schistosity, though occasionally oblique to it. 

 The larger areas usually have their longer diameters parallel to 

 the strike of the schistosity. They are most abundant near the 

 shores of Long Island sound. 



Harrison diorite. This rock is intrusive in the Hudson schist 

 in the towns of Mamaroneck, Harrison and Rye. It consists of 

 quartz, feldspar, hornl)lende and biotite, with accessory titanite 

 and garnet, and less frequently apatite. The feldspars are 

 orthO'Clase and plagioclase (probably oligoclase andesin) in 

 about equal amounts, the two together making up nearly two 

 thirds of the rock. The mass which forms Milton point, near Rye, 

 has been subjected to maich dynamic action and is well banded. 

 The same rock is abundant along the shore of Long Island 

 sound between Port Chester N. Y. and Stamford Ot. A small 

 area of similar rock occurs at Ravenswood L. L, where it out- 

 crops in a long, narrow ridge of northeasterly trend and is in- 

 trusive in the Fordham gneiss. 



