﻿Report 
  of 
  the 
  State 
  Geologist. 
  

  

  451 
  

  

  The 
  mechanism, 
  of 
  the 
  overthrust 
  is, 
  I 
  think, 
  not 
  difficult 
  to 
  

   understand, 
  and 
  I 
  have 
  represented 
  the 
  hypothesis 
  of 
  its 
  develop- 
  

   ment 
  in 
  the 
  diagrams 
  in 
  the 
  above 
  figure, 
  I, 
  being 
  the 
  first 
  stage, 
  

   II, 
  the 
  second 
  stage, 
  and 
  the 
  present 
  conditions 
  the 
  third 
  stage. 
  

  

  FAULl 
  

  

  

  

  Ficj. 
  8 
  

  

  Fig. 
  8.— 
  Overthrust 
  on 
  Sprayt 
  creek. 
  A, 
  cross-section 
  on 
  north 
  bank. 
  Looking 
  north, 
  I 
  and 
  

   II, 
  hypothetical 
  section 
  to 
  illustrate 
  stages 
  of 
  development 
  of 
  the 
  overthrust. 
  

  

  The 
  broken 
  line 
  on 
  I 
  indicates 
  the 
  plane 
  of 
  weakness, 
  the 
  arrow 
  

   the 
  direction 
  of 
  thrust. 
  The 
  fault, 
  sheared 
  diagonally 
  through 
  

   the 
  massive 
  beds 
  of 
  Pentamerus 
  limestone 
  but 
  the 
  softer, 
  thin- 
  

   bedded, 
  underlying 
  limestones 
  in 
  moving 
  forward 
  with 
  the 
  thrust 
  

  

  