﻿Plate 
  15 
  

  

  A 
  ledge 
  of 
  Precambric 
  rock 
  near 
  Loon 
  lake 
  in 
  the 
  northern 
  Adirondacks, 
  

   showing 
  the 
  very 
  ancient 
  Grenville 
  gneiss 
  in 
  sharp 
  contact 
  with 
  syenite. 
  

   The 
  light 
  and 
  dark 
  banded 
  rock 
  on 
  the 
  right 
  is 
  Grenville 
  and 
  the 
  hammer 
  

   is 
  on 
  the 
  contact. 
  

  

  From 
  N. 
  Y. 
  State 
  Mus. 
  Bui. 
  5, 
  p 
  .3 
  

  

  