﻿FEALE.] 
  PALAEOZOIC 
  EOCKS 
  GENERAL 
  CONSIDERATION. 
  79 
  

  

  In 
  New 
  Mexico 
  also 
  Professor 
  Kewberry 
  found 
  the 
  equivalents 
  of 
  the 
  

   Coal-Measures 
  resting 
  directly 
  on 
  the 
  granite.* 
  He 
  also 
  finds 
  evidence 
  

   of 
  the 
  proximity 
  of 
  land, 
  while 
  to 
  the 
  southward 
  there 
  is 
  " 
  proof 
  of 
  the 
  

   uninterrupted 
  existence 
  of 
  an 
  open 
  sea 
  " 
  " 
  throughout 
  the 
  entire 
  Car- 
  

   boniferous 
  epoch."t 
  In 
  Permian 
  times 
  shallower 
  seas 
  seem 
  to 
  have 
  pre- 
  

   vailed 
  over 
  wider 
  areas, 
  with 
  oscillations 
  of 
  the 
  surface, 
  although, 
  in 
  

   Colorado, 
  the 
  general 
  movement 
  was 
  one 
  of 
  subsidence. 
  

  

  The 
  following 
  shows 
  the 
  difference 
  in 
  thickness 
  of 
  the 
  Carboniferous 
  

   rocks 
  in 
  the 
  Appalachian 
  region, 
  the 
  Interior 
  basin, 
  and 
  Colorado 
  : 
  

  

  Appalachian. 
  Interior. 
  Colorado. 
  

  

  Maximum 
  16,125 
  feet. 
  3,750 
  feet. 
  5,000 
  feet. 
  

  

  Minimum 
  1,130 
  feet, 
  4,000 
  feet. 
  

  

  We 
  see 
  that 
  in 
  Colorado 
  the 
  thickness 
  is 
  intermediate 
  between 
  that 
  

   of 
  the 
  Appalachian 
  and 
  that 
  of 
  the 
  interior 
  region. 
  In 
  regard 
  to 
  the 
  

   character 
  of 
  the 
  rocks 
  we 
  notice 
  the 
  same 
  fact. 
  Fragmental 
  rocks 
  form 
  

   16,000 
  feet 
  in 
  the 
  Appalachian 
  region 
  ; 
  500 
  to 
  1,000 
  feet 
  in 
  Colorado, 
  

   and 
  in 
  the 
  interior 
  region 
  1,000 
  to 
  3,000 
  feet. 
  

  

  From 
  what 
  has 
  been 
  written, 
  therefore, 
  it 
  will 
  be 
  seen 
  that 
  the 
  areas 
  

   of 
  highest 
  elevation 
  in 
  Palaeozoic, 
  and 
  perhaps 
  in 
  Pre-Palseozoic 
  times 
  in 
  

   the 
  Kocky 
  Mountain 
  region 
  were 
  in 
  Colorado, 
  and 
  it 
  is 
  an 
  interesting 
  

   fact 
  that 
  at 
  the 
  present 
  time, 
  as 
  far 
  as 
  known, 
  the 
  highest 
  mass 
  of 
  

   mountain 
  elevation 
  is 
  also 
  found 
  there. 
  This 
  is 
  also 
  true 
  of 
  the 
  pla- 
  

   teaus, 
  which 
  range 
  from 
  8,000 
  feet 
  to 
  9,000 
  feet. 
  Taking 
  the 
  mean 
  ele- 
  

   vation 
  of 
  Colorado, 
  6,600 
  feet, 
  we 
  find 
  it 
  greater 
  than 
  that 
  of 
  any 
  other 
  

   State 
  or 
  Territory, 
  Wyoming 
  being 
  next, 
  with 
  a 
  mean 
  elevation 
  of 
  6,450 
  

   feet.f 
  

  

  Although 
  the 
  Eocky 
  Mountains, 
  as 
  we 
  now 
  know 
  them, 
  had 
  no 
  exist- 
  

   ence 
  until 
  Tertiary 
  time, 
  still, 
  as 
  pointed 
  out 
  by 
  Dr. 
  ]!Tewberry,§ 
  the 
  

   western 
  part 
  of 
  North 
  America 
  was 
  outlined 
  from 
  early 
  times 
  by 
  groups 
  

   of 
  islands 
  and 
  broad 
  continental 
  surfaces 
  of 
  dry 
  land. 
  

  

  A 
  portion 
  of 
  this 
  land, 
  perhaps 
  as 
  islands, 
  existed 
  in 
  Colorado, 
  as 
  we 
  

   have 
  noted 
  in 
  preceding 
  portions 
  of 
  this 
  chapter. 
  In 
  regard 
  to 
  coal 
  in 
  

   the 
  Carboniferous, 
  none 
  has 
  been 
  found 
  in 
  Colorado. 
  On 
  Eagle 
  Eiver 
  

   there 
  were 
  patches 
  of 
  carbonaceous 
  material 
  in 
  the 
  Coal-Measure 
  rocks, 
  

   and 
  in 
  New 
  Mexico 
  a 
  thin 
  bed 
  of 
  coal 
  occurs 
  in 
  the 
  Coal-Measures 
  near 
  

   Santa 
  ¥6. 
  Still 
  the 
  conditions 
  do 
  not 
  seem 
  to 
  have 
  been 
  very 
  favorable 
  

   for 
  the 
  formation 
  of 
  coal. 
  

  

  ^Report 
  of 
  Exploring 
  Expedition 
  from 
  Santa 
  F6 
  to 
  junction 
  of 
  Grand 
  and 
  Green, 
  pp. 
  42-47. 
  

   t 
  Ibid., 
  p. 
  17. 
  

  

  t 
  List 
  of 
  Elevations, 
  by 
  H. 
  Gannett, 
  United 
  States 
  Geological 
  Survey, 
  third 
  edition, 
  p. 
  

   72. 
  

  

  $ 
  Ives's 
  Colorado 
  Expedition, 
  Geological 
  Report, 
  p. 
  47. 
  

  

  