﻿130 
  Spencer 
  — 
  Devonian 
  Strata 
  hi 
  Colorado. 
  

  

  Aspen 
  has 
  given 
  sny 
  evidence 
  of 
  a 
  positive 
  nature, 
  but 
  a 
  re- 
  

   examination 
  by 
  Dr. 
  Girty 
  of 
  the 
  fossils 
  collected 
  at 
  various 
  

   localities 
  in 
  the 
  central 
  portion 
  of 
  the 
  State 
  has 
  resulted 
  in 
  

   establishing 
  the 
  occurrence 
  of 
  Devonian 
  strata 
  in 
  this 
  region. 
  

   It 
  seems 
  desirable 
  to 
  bring 
  together 
  in 
  this 
  place 
  all 
  the 
  available 
  

   information 
  concerning 
  the 
  strata 
  of 
  Central 
  Colorado 
  which 
  

   are 
  now 
  known 
  to 
  be 
  of 
  Devonian 
  age. 
  Some 
  of 
  the 
  data 
  

   have 
  not 
  been 
  published 
  hitherto. 
  

  

  At 
  Leadville 
  Emmons* 
  was 
  not 
  able 
  to 
  find 
  strata 
  which 
  

   could 
  be 
  referred 
  with 
  certainty 
  to 
  the 
  Devonian. 
  A 
  meagre 
  

   Silurian 
  fauna 
  was 
  found 
  in 
  the 
  lower 
  part 
  of 
  the 
  sedimentary 
  

   series, 
  while 
  higher 
  in 
  the 
  section, 
  Carboniferous 
  fossils 
  were 
  

   also 
  found, 
  but 
  between 
  these 
  there 
  was 
  a 
  considerable 
  thickness 
  

   of 
  strata 
  from 
  which 
  no 
  organic 
  remains 
  were 
  obtained. 
  In 
  the 
  

   absence 
  of 
  adequate 
  fossils, 
  and 
  in 
  view 
  of 
  the 
  opinion 
  expressed 
  

   by 
  R. 
  P. 
  Whitfield, 
  f 
  that 
  the 
  characters 
  of 
  Rhynconella 
  End- 
  

   lichi 
  were 
  Carboniferous 
  rather 
  than 
  Devonian, 
  it 
  was 
  con- 
  

   cluded 
  that 
  Devonian 
  strata 
  had 
  not 
  yet 
  been 
  found 
  in 
  Colorado, 
  

   and 
  it 
  was 
  thought 
  advisable 
  to 
  apportion 
  the 
  lower 
  part 
  of 
  the 
  

   Paleozoic 
  section 
  between 
  the 
  Silurian 
  and 
  the 
  Carboniferous. 
  

   Between 
  the 
  white 
  limestone 
  of 
  the 
  Silurian 
  and 
  the 
  blue 
  

   limestone, 
  which 
  was 
  classified 
  as 
  Lower 
  Carboniferous 
  because 
  

   of 
  the 
  fossils 
  which 
  were 
  found 
  in 
  its 
  upper 
  part, 
  there 
  is 
  a 
  

   quartzite 
  which 
  is 
  typically 
  about 
  forty 
  feet 
  in 
  thickness. 
  This 
  

   siliceous 
  band 
  was 
  called 
  the 
  " 
  Parting 
  Quartzite 
  " 
  and 
  it 
  was 
  

   given 
  position 
  as 
  the 
  uppermost 
  member 
  of 
  the 
  Silurian. 
  

   Between 
  it 
  and 
  the 
  fossiliferous 
  horizons 
  of 
  the 
  blue 
  limestone 
  

   there 
  are 
  nearly 
  200 
  feet 
  of 
  limestone 
  which 
  are 
  entirely 
  unfos- 
  

   siliferous. 
  It 
  is 
  this 
  portion 
  of 
  the 
  limestone 
  immediately 
  

   above 
  the 
  " 
  Parting 
  Quartzite 
  " 
  that 
  probably 
  corresponds 
  

   with 
  the 
  Devonian 
  of 
  the 
  Gunnison 
  and 
  Salida 
  sections, 
  

   described 
  in 
  what 
  follows. 
  

  

  With 
  the 
  knowledge 
  gained 
  in 
  the 
  Leadville 
  work, 
  Mr. 
  

   Emmons 
  was 
  able 
  to 
  establish 
  the 
  general 
  correspondence 
  of 
  

   the 
  Paleozoic 
  rocks 
  at 
  several 
  places 
  adjacent, 
  and 
  his 
  general 
  

   results 
  have 
  been 
  found 
  correct 
  by 
  those 
  who 
  have 
  made 
  more 
  

   detailed 
  examinations 
  under 
  his 
  direction. 
  

  

  During 
  the 
  field 
  seasons 
  of 
  1885-S6, 
  Mr. 
  George 
  H. 
  Eld- 
  

   ridge 
  was 
  engaged 
  in 
  the 
  study 
  of 
  the 
  stratified 
  rocks 
  of 
  the 
  

   Gunnison 
  region. 
  At 
  this 
  time, 
  he 
  also 
  made 
  careful 
  sections 
  

   and 
  collections 
  in 
  the 
  vicinity 
  of 
  Salida. 
  At 
  both 
  places, 
  Mr. 
  

   Eldridge 
  was 
  able 
  to 
  recognize 
  the 
  " 
  Parting 
  Quartzite," 
  and 
  

   in 
  the 
  limestone 
  strata 
  which 
  immediately 
  overlie 
  it, 
  fossils 
  

  

  * 
  Geology 
  and 
  Mining 
  Industry 
  of 
  Leadville. 
  Monograph 
  U. 
  S. 
  Geol. 
  Surv. 
  T 
  

   xii, 
  p. 
  56. 
  

   f 
  Idem. 
  

  

  