﻿290 
  W. 
  H. 
  Twenhofel 
  — 
  The 
  Comanchean 
  and 
  

  

  uplift 
  toward 
  the 
  close 
  of 
  marine 
  deposition 
  and 
  conse- 
  

   quent 
  extension 
  of 
  terrestrial 
  deposition 
  to 
  the 
  limit 
  of 
  

   marine 
  retirement. 
  This 
  was 
  at 
  least 
  as 
  far 
  southward 
  

   as 
  northern 
  Texas, 
  as 
  shown 
  by 
  the 
  Woodbine 
  formation 
  

   which 
  is 
  the 
  equivalent 
  of 
  a 
  part 
  of 
  the 
  "Dakota." 
  

   However 
  the 
  depositions 
  were 
  accomplished, 
  there 
  re- 
  

   sulted 
  a 
  dovetailing 
  of 
  marine 
  and 
  terrestrial 
  sediments, 
  

   the 
  former 
  everywhere 
  containing 
  a 
  Washita 
  fauna, 
  the 
  

   latter 
  in 
  most 
  cases 
  a 
  "Dakota" 
  flora. 
  Figure 
  1 
  shows 
  

   this 
  in 
  ideal 
  cross-section. 
  

  

  The 
  generalized 
  cross-section 
  shows 
  that 
  the 
  "Dakota" 
  

   sandstone 
  of 
  Kansas, 
  with 
  its 
  contained 
  dicotyledonous 
  

   flora, 
  and 
  the 
  marine 
  strata 
  known 
  as 
  the 
  Kiowa, 
  Men- 
  

   tor, 
  etc., 
  are 
  of 
  one 
  age 
  and 
  were 
  deposited 
  during 
  the 
  

   same 
  period 
  of 
  time, 
  the 
  former 
  being 
  the 
  terrestrial 
  

   equivalents 
  of 
  the 
  latter. 
  This 
  conclusion 
  can 
  be 
  main- 
  

   tained 
  to 
  the 
  top 
  of 
  the 
  last 
  stratum 
  containing 
  marine 
  

   fossils. 
  It 
  is 
  possible 
  that 
  a 
  disconformity 
  and 
  a 
  strati- 
  

   graphic 
  break 
  may 
  occur 
  in 
  the 
  upper 
  member 
  of 
  the 
  

   "Dakota," 
  but 
  on 
  this 
  point 
  the 
  writer 
  has 
  no 
  informa- 
  

   tion. 
  On 
  the 
  other 
  hand, 
  it 
  may 
  actually 
  be 
  that 
  terres- 
  

   trial 
  deposition 
  continued 
  somewhere 
  between 
  Kansas 
  

   and 
  Texas 
  without 
  serious 
  break 
  from 
  the 
  close 
  of 
  the 
  

   retirement 
  of 
  the 
  Washita 
  sea 
  to 
  the 
  appearance 
  of 
  

   the 
  Benton 
  sea. 
  This 
  is, 
  however, 
  considered 
  unlikely. 
  

   That 
  a 
  considerable 
  period 
  of 
  time 
  is 
  involved 
  between 
  

   the 
  retirement 
  of 
  the 
  Washita 
  sea 
  and 
  the 
  invasion 
  of 
  

   the 
  Benton 
  sea 
  is 
  suggested 
  by 
  the 
  decided 
  differences 
  

   between 
  the 
  two 
  faunas. 
  

  

  Correlates 
  of 
  the 
  Kansas 
  Comanchean. 
  

  

  In 
  the 
  preceding 
  discussion 
  it 
  has 
  been 
  tacitly 
  assumed 
  

   that 
  the 
  marine 
  beds 
  of 
  the 
  Kansas 
  sequence 
  are 
  the 
  

   equivalent 
  of 
  the 
  Washita 
  of 
  the 
  Texas 
  sequence. 
  This 
  

   appears 
  to 
  be 
  the 
  most 
  reasonable 
  conclusion 
  in 
  the 
  light 
  

   of 
  the 
  facts 
  known' 
  at 
  present. 
  It 
  is 
  true 
  that 
  there 
  are 
  

   some 
  things 
  in 
  the 
  fauna 
  which 
  are 
  of 
  Fredericksburg 
  

   aspect; 
  but 
  for 
  the 
  greater 
  part, 
  the 
  species 
  are 
  more 
  

   like 
  those 
  of 
  the 
  Washita. 
  This 
  correlation 
  makes 
  the 
  

   Dakota—certainly 
  the 
  "Dakota" 
  of 
  Kansas 
  — 
  of 
  Washita 
  

   age, 
  taking 
  it 
  from 
  the 
  Upper 
  and 
  placing 
  it 
  in 
  the 
  Lower 
  

   Cretaceous, 
  as 
  these 
  two 
  divisions 
  have 
  been 
  defined 
  in 
  

   the 
  United 
  States. 
  

  

  About 
  the 
  mouth 
  of 
  the 
  Big 
  Sioux 
  River 
  in 
  south- 
  

  

  