﻿PEALE] 
  MESOZOIC 
  FORMATIONS 
  LOWER 
  CRETACEOUS-COAL. 
  91 
  

  

  In 
  Arizona, 
  Dr. 
  I^ewberry 
  found 
  the 
  following 
  fossils 
  in 
  the 
  lower 
  

   division 
  of 
  the 
  Cretaceous 
  ; 
  Ammonites 
  pericarinatus, 
  Inoceramus 
  Crispii, 
  

   Gryphcea 
  Pitcheri, 
  and 
  Pinna 
  ? 
  lingula. 
  He 
  has 
  no 
  doubt 
  of 
  the 
  parallel- 
  

   ism 
  of 
  the 
  group 
  of 
  sandstones 
  from 
  which 
  they 
  were 
  obtained 
  with 
  

   those 
  of 
  the 
  base 
  of 
  Meek 
  and 
  Hayden's 
  Cretaceous 
  section,* 
  

  

  Professor 
  Meek 
  refers 
  the 
  beds 
  from 
  which 
  Newberry 
  obtained 
  the 
  

   fossils 
  given 
  in 
  list 
  above 
  to 
  the 
  Dakota 
  group. 
  The 
  animal 
  remains 
  

   found 
  in 
  the 
  Dakota 
  group 
  in 
  Kansas 
  are 
  distinct 
  in 
  species 
  from 
  those 
  

   found 
  in 
  the 
  Upper 
  Missouri 
  region, 
  and 
  the 
  identity 
  of 
  the 
  beds 
  is 
  

   based 
  on 
  the 
  fossil 
  leaves 
  found 
  in 
  them 
  and 
  by 
  their 
  lithological 
  posi- 
  

   tion. 
  In 
  the 
  two 
  sections 
  given 
  above 
  we 
  have 
  a 
  much 
  greater 
  resem- 
  

   blance, 
  and, 
  taken 
  in 
  connection 
  with 
  the 
  position 
  at 
  the 
  base 
  of 
  the 
  Cre- 
  

   taceous, 
  I 
  think 
  there 
  is 
  but 
  little 
  doubt 
  of 
  the 
  identity 
  of 
  the 
  beds. 
  It 
  

   is 
  possible 
  that 
  Powell 
  includes 
  a 
  portion 
  of 
  the 
  Fort 
  Benton 
  group 
  

   with 
  the 
  Henry's 
  Fork, 
  as 
  some 
  of 
  the 
  fossils 
  would 
  seem 
  to 
  indicate. 
  

   It 
  is 
  more 
  likely, 
  however, 
  that, 
  as 
  our 
  knowledge 
  of 
  the 
  animal 
  life 
  of 
  

   the 
  Dakota 
  group 
  is 
  extended, 
  we 
  will 
  find 
  that 
  paleontological 
  lines 
  

   cannot 
  be 
  sharply 
  drawn, 
  and 
  that 
  we 
  will 
  have 
  to 
  divide 
  the 
  Creta- 
  

   ceous 
  formation 
  "^lithologically. 
  The 
  following 
  genera 
  of 
  fossil 
  plants 
  

   are 
  represented 
  in 
  the 
  Dakota 
  group 
  in 
  Kansas, 
  the 
  Upper 
  Missouri 
  

   region, 
  and 
  in 
  ISTew 
  Mexico 
  and 
  adjacent 
  parts 
  of 
  Arizona, 
  Utafi, 
  and 
  

   Colorado 
  : 
  Splienopterls, 
  Salix, 
  Quereus, 
  Plantanus, 
  and 
  Phyllites. 
  There 
  

   are 
  other 
  genera 
  common 
  to 
  Arizona 
  and 
  Kansas. 
  

  

  From 
  what 
  has 
  been 
  written, 
  I 
  think 
  it 
  is 
  evident 
  that 
  Powell's 
  Henry's 
  

   Fork 
  group 
  is 
  the 
  equivalent 
  of 
  the 
  Dakota 
  group, 
  and 
  should 
  be 
  so 
  

   called, 
  especially 
  as 
  King 
  has 
  called 
  it 
  so 
  at 
  the 
  typical 
  locality 
  men- 
  

   tioned 
  by 
  Powell. 
  

  

  The 
  formation 
  has 
  been 
  recognized 
  without 
  difiiculty 
  in 
  British 
  

   America, 
  in 
  Arizona, 
  Kansas, 
  New 
  Mexico, 
  Wyoming, 
  and 
  Montana. 
  

  

  Goal 
  in 
  the 
  Dakota 
  group. 
  — 
  In 
  the 
  report 
  for 
  1874, 
  I 
  noticed 
  the 
  ex- 
  

   istence 
  of 
  lignite 
  in 
  the 
  Dakota 
  group, 
  just 
  below 
  the 
  upper, 
  massive 
  

   sandstone. 
  This 
  lignitic 
  band 
  seems 
  to 
  be 
  persistent 
  in 
  this 
  portion 
  of 
  

   the 
  West, 
  as 
  in 
  Eastern 
  Colorado. 
  At 
  most 
  localities 
  the 
  coal 
  is 
  of 
  no 
  

   economic 
  importance. 
  In 
  the 
  caQon 
  of 
  Uncompahgre 
  Eiver, 
  below 
  the 
  

   mouth 
  of 
  the 
  Dallas 
  Fork, 
  there 
  is 
  a 
  bed 
  of 
  coal 
  which 
  has 
  been 
  changed 
  

   to 
  anthracite 
  by 
  a 
  dike 
  of 
  trachytic 
  rock. 
  

  

  MIDDLE 
  AND 
  UPPER 
  CRETACEOUS. 
  

  

  In 
  the 
  Uncompahgre 
  Valley, 
  on 
  both 
  sides 
  of 
  the 
  river 
  until 
  the 
  

   canon 
  is 
  reached, 
  there 
  are 
  exposures 
  of 
  shales 
  belonging 
  to 
  No. 
  2 
  and 
  

   No. 
  3. 
  They 
  are 
  generally 
  so 
  much 
  concealed 
  that 
  perfect 
  sections 
  

   cannot 
  be 
  made. 
  East 
  of 
  the 
  Uncompahgre 
  Agency 
  the 
  thickness 
  of 
  the 
  

   beds 
  is 
  about 
  3,000 
  feet. 
  At 
  the 
  base 
  are 
  the 
  black 
  shales 
  of 
  No. 
  2 
  and 
  

   No. 
  3, 
  with 
  characteristic 
  fossils. 
  Above 
  these 
  are 
  yellow 
  and 
  light- 
  

   gray 
  shales, 
  passing 
  into 
  more 
  arenaceous 
  layers 
  that 
  are 
  exposed 
  near 
  

   the 
  top. 
  In 
  the 
  latter, 
  near 
  the 
  summit 
  of 
  the 
  divide 
  between 
  Uncoiqi- 
  

   pahgre 
  and 
  Cebolla 
  Creek, 
  there 
  are 
  bands 
  of 
  lignite. 
  It 
  is 
  of 
  rather 
  

   poor 
  quality 
  as 
  far 
  as 
  seen, 
  crumbling 
  rapidly 
  on 
  exposure 
  to 
  the 
  atmos- 
  

   phere. 
  On 
  the 
  west 
  side 
  of 
  the 
  Uncompahgre, 
  only 
  the 
  lower 
  part 
  of 
  the 
  

   series 
  shows, 
  while 
  on 
  the 
  divide 
  just 
  mentioned 
  we 
  have 
  a 
  portion, 
  at 
  

   least, 
  of 
  the 
  Upper 
  Cretaceous, 
  forming 
  the 
  top 
  of 
  the 
  ridge. 
  It 
  is 
  the 
  

   only 
  place 
  in 
  the 
  district 
  where 
  it 
  occurs. 
  As 
  we 
  go 
  west 
  from 
  the 
  

   Uncompahgre, 
  on 
  the 
  Uncompahgre 
  plateau, 
  the 
  shales 
  soon 
  disappear, 
  

   and 
  the 
  Dakota 
  comes 
  to 
  the 
  surface, 
  on 
  account 
  of 
  a 
  slight 
  monoclinal 
  

  

  *Ives's 
  Colorado 
  Exploring' 
  Expedition 
  ; 
  Geological 
  Report, 
  p. 
  85. 
  

  

  