﻿PLATE 
  III. 
  

  

  J. 
  H. 
  Merrill, 
  Photo. 
  

  

  Precambrian 
  sheared 
  granite. 
  Lake 
  Mahopac, 
  N. 
  Y. 
  

   Photomicrograph 
  in 
  polarized 
  light, 
  enlargement 
  22 
  diameters. 
  

  

  