﻿Plate 29 



Photomicrograph of Yonkers gneiss of the type to be used in the new 

 Kensico dam. Dinnan quarries. Magnified 30 diameters 



■■ %i : &M0'\. 







Photomicrograph of diorite gneiss from " Garden quarry.'' Magnifica- 

 tion 30 diameters. The constituents are hornblende, biotite, feldspars 

 and quartz. 



