﻿Dakota 
  Strata 
  of 
  Kansas. 
  289 
  

  

  3. 
  Blue 
  paper 
  shale 
  with 
  2 
  feet 
  of 
  pale 
  yellow 
  sandstone. 
  

   Fossil 
  leaves 
  of 
  dicotyledons 
  are 
  present 
  in 
  both 
  shale 
  

   and 
  sandstone. 
  The 
  zone 
  is 
  probably 
  of 
  terrestrial 
  

   origin 
  26 
  feet 
  

  

  2. 
  Shell 
  limestone 
  with 
  fossils 
  identical 
  to 
  those 
  in 
  the 
  Kiowa, 
  

   the 
  zone 
  correlating 
  best 
  with 
  a 
  zone 
  about 
  3(3 
  feet 
  

   from 
  the 
  base 
  of 
  the 
  latter 
  as 
  exposed 
  near 
  Belvidere, 
  

   Comanche 
  County. 
  Common 
  fossils 
  are 
  : 
  Cardium 
  kan- 
  

   sasense 
  Meek, 
  Cyprimeria 
  kiowana 
  Cragin, 
  Turritella 
  

   near 
  T. 
  seriatim-granulata 
  Roemer 
  2-3 
  feet 
  

  

  1. 
  Dark 
  blue 
  gypsiferous 
  shales, 
  either 
  of 
  terrestrial 
  origin 
  or 
  

   of 
  a 
  lagoon 
  adjacent 
  to 
  the 
  sea 
  30 
  feet 
  

  

  The 
  Mentor 
  beds 
  were 
  deposited 
  over 
  an 
  area 
  on 
  

   which 
  the 
  sea 
  and 
  the 
  land 
  contended 
  for 
  supremacy 
  and 
  

   over 
  which 
  the 
  strand-line 
  advanced 
  and 
  retreated 
  sev- 
  

   eral 
  times. 
  The 
  terrestrial 
  deposits 
  are 
  in 
  part 
  the 
  

   alluvial 
  deposits 
  of 
  wandering 
  rivers, 
  in 
  part 
  delta 
  de- 
  

   posits, 
  and 
  possibly 
  in 
  part 
  deposits 
  by 
  wind. 
  

  

  Summary 
  of 
  the 
  Conditions 
  of 
  Origin 
  of 
  the 
  Comanchean 
  

  

  of 
  Kansas. 
  

  

  It 
  is 
  obvious 
  that 
  the 
  strata 
  of 
  the 
  southern 
  and 
  cen- 
  

   tral 
  areas 
  were 
  once 
  connected, 
  and 
  it 
  may 
  be 
  that 
  con- 
  

   nection 
  beneath 
  the 
  Tertiary 
  cover 
  still 
  exists. 
  The 
  

   strata 
  were 
  deposited 
  under 
  conditions 
  which 
  permitted 
  

   the 
  sea 
  and 
  the 
  land 
  to 
  contend 
  with 
  each 
  other 
  for 
  the 
  

   places 
  of 
  deposition 
  ; 
  that 
  is, 
  in 
  the 
  border 
  zone 
  between 
  

   the 
  two 
  realms 
  of 
  sedimentation, 
  held 
  alternately 
  by 
  the 
  

   land 
  and 
  the 
  sea. 
  At 
  least 
  three 
  times, 
  perhaps 
  five, 
  the 
  

   sea 
  advanced, 
  and 
  as 
  many 
  times 
  retreated. 
  These 
  to- 
  

   and-fro 
  migrations 
  could 
  have 
  been 
  produced 
  by 
  oscilla- 
  

   tion 
  of 
  sea-level, 
  due 
  to 
  cyclic 
  upward 
  and 
  downward 
  

   movement 
  of 
  varying 
  extent 
  ; 
  or 
  to 
  intermittent 
  and 
  dif- 
  

   ferential 
  downward 
  movement. 
  During 
  the 
  times 
  of 
  

   stability, 
  there 
  would 
  have 
  been 
  a 
  building 
  outward 
  of 
  

   the 
  shore-line 
  by 
  terrestrial 
  sediments, 
  and 
  during 
  the 
  

   times 
  of 
  rapid 
  downward 
  movement, 
  a 
  northward 
  inva- 
  

   sion 
  by 
  the 
  sea, 
  the 
  thickness 
  and 
  character 
  of 
  the 
  de- 
  

   posits 
  of 
  each 
  realm 
  being 
  consequent 
  upon 
  the 
  extent 
  

   of 
  movement. 
  Which 
  type 
  of 
  movement 
  prevailed, 
  the 
  

   writer 
  does 
  not 
  know, 
  but 
  the 
  more 
  simple 
  theory 
  has 
  the 
  

   greater 
  appeal; 
  that 
  is, 
  that 
  the 
  major 
  movement 
  was 
  

   downwarping 
  rather 
  than 
  of 
  an 
  oscillatory 
  nature, 
  with 
  

  

  