﻿U. 
  S. 
  GEOLOGICAL 
  SURVEY 
  

  

  BULLETIN 
  NO. 
  322 
  PL. 
  IV 
  

  

  B 
  

  

  SOFT 
  WHITE 
  DIATOMACEOUS 
  SHALE. 
  

  

  A. 
  Characteristic 
  exposure 
  north 
  of 
  Casmalia. 
  B. 
  Detail 
  of 
  weathering 
  at 
  Burton 
  Mesa, 
  east 
  of 
  Pine 
  

   Canyon. 
  Photographs 
  by 
  Ralph 
  Arnold. 
  

  

  