﻿Dakota 
  Strata 
  of 
  Kansas. 
  283 
  

  

  western 
  limits 
  of 
  the 
  band 
  cross 
  the 
  Comanchean 
  strata 
  

   to 
  rest 
  npon 
  the 
  Permian; 
  the 
  latter 
  in 
  this 
  portion 
  of 
  

   the 
  state 
  constitutes 
  the 
  base 
  on 
  which 
  the 
  Comanchean 
  

   sediments 
  were 
  deposited. 
  Southward 
  of 
  the 
  Coman- 
  

   chean 
  band, 
  with 
  the 
  exception 
  of 
  the 
  outlier 
  noted 
  and 
  

   others 
  in 
  Oklahoma, 
  the 
  Comanchean 
  strata 
  have 
  been 
  

   removed 
  by 
  erosion, 
  a 
  great 
  deal 
  of 
  which 
  appears 
  to 
  

   have 
  been 
  accomplished 
  in 
  post-Cretaceous 
  time 
  and 
  

   antecedent 
  to 
  Tertiary 
  deposition 
  in 
  this 
  region. 
  

  

  The 
  sequence 
  in 
  the 
  southern 
  portion 
  of 
  the 
  state 
  is 
  as 
  

   follows 
  : 
  

  

  Medicine 
  beds 
  6 
  

  

  Reeder 
  sandstone, 
  terrestrial, 
  "Dakota" 
  flora. 
  . 
  . 
  20 
  ± 
  feet 
  

  

  Kirby 
  clays, 
  7 
  terrestrial, 
  "Dakota" 
  flora 
  50 
  ± 
  " 
  

  

  Greenleaf 
  sandstone, 
  7 
  marine, 
  Washita 
  fanna. 
  ... 
  50 
  ± 
  " 
  

  

  Spring 
  Creek 
  clays, 
  7 
  marine, 
  Washita 
  fauna 
  50 
  ± 
  tl 
  

  

  Kiowa 
  shales 
  and 
  limestones, 
  marine, 
  Washita 
  

  

  fauna 
  140 
  ± 
  ' 
  ' 
  

  

  Cheyenne 
  sandstone, 
  terrestrial, 
  "Dakota" 
  flora. 
  100 
  ± 
  " 
  

  

  The 
  Cheyenne 
  sandstone 
  consists 
  of 
  light 
  gray 
  to 
  yel- 
  

   low 
  quartz 
  sandstone 
  with 
  subordinate 
  interbedded 
  shale. 
  

   The 
  bedding 
  is 
  extremely 
  irregular 
  and 
  discontinuous. 
  

   Lateral 
  gradation 
  from 
  one 
  to 
  another 
  texture 
  of 
  sand 
  

   or 
  to 
  shale 
  is 
  very 
  abundant. 
  Cross-lamination 
  is 
  pres- 
  

   ent 
  in 
  nearly 
  every 
  horizon, 
  the 
  foresets 
  tending 
  to 
  have 
  

   southern 
  inclinations, 
  being 
  quite 
  steep, 
  and 
  averaging 
  

   around 
  3 
  to 
  4 
  feet, 
  although 
  some 
  are 
  very 
  much 
  longer. 
  

   Interbedded 
  shales 
  are 
  most 
  commonly 
  of 
  dark 
  colors. 
  

   The 
  sand 
  grains 
  vary 
  from 
  extremely 
  fine 
  to 
  coarse, 
  in 
  

   some 
  horizons 
  being 
  almost 
  flour-like, 
  while 
  in 
  others 
  

   there 
  are 
  streaks 
  of 
  quartz 
  and 
  chert 
  pebbles. 
  The 
  

   materials 
  are 
  poorly 
  cemented 
  and 
  are 
  thus 
  easily 
  eroded. 
  

   Badland 
  features 
  are 
  rather 
  characteristic 
  of 
  the 
  expo- 
  

   sures. 
  

  

  Fossil 
  leaves 
  of 
  dicotyledons 
  and 
  other 
  plant 
  matter 
  

   are 
  locally 
  quite 
  common 
  in 
  some 
  horizons, 
  particularly 
  

   in 
  the 
  upper 
  part. 
  The 
  credit 
  for 
  the 
  discovery 
  of 
  the 
  

   dicotyledonous 
  flora 
  belongs 
  to 
  R. 
  T. 
  Hill 
  and 
  members 
  

   of 
  his 
  party. 
  8 
  Vegetable 
  remains 
  in 
  the 
  form 
  of 
  silici- 
  

   fied 
  logs 
  had 
  previously 
  been 
  discovered 
  in 
  this 
  formation 
  

   by 
  Cragin 
  9 
  and 
  he 
  had 
  described 
  a 
  cycad 
  therefrom 
  as 
  

  

  G 
  F. 
  W. 
  Cragin, 
  Am. 
  Geol. 
  16, 
  381, 
  1895. 
  

  

  7 
  C. 
  N. 
  Gould, 
  this 
  Journal, 
  5, 
  169-175, 
  1898. 
  

  

  8 
  R. 
  T. 
  Hill, 
  this 
  Journal, 
  49, 
  473, 
  1895. 
  

  

  9 
  F. 
  W. 
  Cragin, 
  Bull. 
  Washburn 
  Coll. 
  Lab. 
  Nat. 
  Hist., 
  vol. 
  2, 
  No. 
  10, 
  pp. 
  

   65-66, 
  71, 
  1889. 
  

  

  