﻿130 
  

  

  8. 
  Powers. 
  — 
  The 
  Butler 
  Salt 
  Dome. 
  

  

  on 
  the 
  south 
  side 
  of 
  the 
  dome 
  creeks 
  meander 
  in 
  either 
  

   direction. 
  Burton 
  Hollow 
  creek 
  drains 
  from 
  the 
  south 
  

   into 
  the 
  saline 
  near 
  the 
  divide 
  and 
  runs 
  northwest 
  and 
  

   north. 
  It 
  is 
  joined 
  in 
  a 
  radial 
  fashion 
  by 
  short 
  branches 
  

   from 
  the 
  inside 
  and 
  by 
  long 
  branches 
  from 
  the 
  outside. 
  

   Of 
  the 
  latter 
  the 
  first 
  two 
  are 
  nameless, 
  the 
  third 
  is 
  

   Mason 
  Hollow 
  (McCormick 
  branch), 
  and 
  the 
  fourth 
  Mill 
  

   Branch. 
  Rocky 
  Ford 
  creek 
  probably 
  forms 
  another 
  

   radius 
  from 
  the 
  north 
  beyond 
  the 
  limits 
  of 
  the 
  accom- 
  

   panying 
  map. 
  Burton 
  Hollow 
  creek 
  expands 
  to 
  form 
  

   the 
  shallow 
  Blue 
  Lake 
  at 
  the 
  edge 
  of 
  the 
  Trinity 
  River 
  

   " 
  bottom 
  " 
  (overflow 
  plain) 
  and 
  this 
  lake 
  with 
  its 
  ramifi- 
  

  

  Fig. 
  2. 
  

  

  Fig. 
  2. 
  — 
  Hypothetical 
  cross 
  section 
  of 
  the 
  Butler 
  salt 
  dome, 
  at 
  Llewellyn 
  

   gin 
  lake 
  showing 
  salt 
  core 
  overlain 
  in 
  part 
  by 
  limestone 
  cap 
  rock 
  (C) 
  and 
  

   flanked 
  by 
  sediments 
  of 
  Navarro 
  (?) 
  (N), 
  Midway 
  (?) 
  (M), 
  Wilcox 
  (W), 
  

   Mount 
  Selman 
  (M. 
  S.) 
  ages. 
  The 
  salt 
  core 
  and 
  cap 
  rock 
  are 
  probably 
  over- 
  

   . 
  lain 
  by 
  sand 
  and 
  clay 
  to 
  which 
  no 
  age 
  can 
  be 
  assigned. 
  The 
  well 
  at 
  the 
  gin 
  

   is 
  shown. 
  

  

  cations 
  extends 
  around 
  a 
  hill 
  and 
  eastward 
  draining 
  in 
  

   obscure 
  channels 
  across 
  the 
  "bottom" 
  and 
  into 
  the 
  river. 
  

  

  At 
  the 
  divide 
  on 
  the 
  south 
  side 
  of 
  the 
  dome 
  Saline 
  

   creek 
  starts 
  eastward, 
  turns 
  northeast, 
  and 
  is 
  joined 
  by 
  

   radial 
  branches 
  from 
  the 
  inside 
  and 
  from 
  the 
  outside. 
  

   The 
  difference 
  in 
  elevation 
  of 
  the 
  Trinity 
  "bottom" 
  and 
  

   of 
  the 
  divide 
  is 
  about 
  35 
  feet, 
  giving 
  the 
  drainage 
  a 
  fall 
  

   of 
  about 
  20 
  feet 
  to 
  the 
  mile. 
  Hence, 
  the 
  prairies 
  are 
  in 
  

   a 
  condition 
  of 
  mature 
  erosion 
  although 
  the 
  other 
  streams 
  

   of 
  the 
  region 
  have 
  not 
  advanced 
  that 
  far 
  in 
  the 
  present 
  

   cycle 
  of 
  erosion. 
  

  

  Hills 
  form 
  a 
  rim 
  around 
  the 
  saline 
  prairie 
  on 
  both 
  

   sides. 
  Those 
  on 
  the 
  outside 
  are 
  the 
  higher 
  and 
  the 
  

   greatest 
  relief 
  is 
  between 
  60 
  and 
  70 
  feet. 
  Rocky 
  Moun- 
  

  

  