﻿ENDLicH.] 
  RESUME 
  OF 
  CHAPTER 
  I. 
  139 
  

  

  Many 
  of 
  the 
  formations 
  usually 
  met 
  with 
  in 
  the 
  Eocky 
  Mountains 
  are 
  

   represented 
  here, 
  and 
  have 
  been 
  discussed 
  at 
  their 
  proper 
  places. 
  

   Metamorphics 
  are 
  found 
  in 
  the 
  highest 
  portions 
  of 
  the 
  district, 
  main- 
  

   taining 
  their 
  general 
  association 
  with 
  the 
  most 
  lofty 
  peaks 
  of 
  the 
  main 
  

   Eocky 
  Mountain 
  chain. 
  Of 
  the 
  sedimentary 
  formations, 
  the 
  older 
  ones 
  

   have 
  not 
  appeared, 
  probably 
  having 
  furnished 
  the 
  material 
  for 
  the 
  numer- 
  

   ous 
  varieties 
  of 
  granite, 
  gneiss, 
  and 
  schists 
  that 
  compose 
  the 
  " 
  core" 
  of 
  

   the 
  most 
  prominent 
  range 
  of 
  the 
  district. 
  Carboniferous 
  is 
  represented 
  

   in 
  its 
  older 
  and 
  middle 
  members. 
  The 
  opportune 
  discovery 
  of 
  Carbonifer- 
  

   ous 
  fossils 
  in 
  limestone 
  strata 
  inclosed 
  between 
  the 
  massive 
  red 
  sand- 
  

   stones, 
  at 
  three 
  localities, 
  has 
  deliuitely 
  settled 
  the 
  question 
  as 
  to 
  the 
  

   age 
  of 
  the 
  latter. 
  They 
  are 
  sufficiently 
  characteristic 
  in 
  their 
  habitat 
  to 
  

   be 
  distinguished 
  from 
  the 
  younger 
  Triassic 
  beds, 
  even 
  should 
  palaeon- 
  

   tological 
  evidence 
  be 
  wanting. 
  Of 
  older 
  Mesozoic 
  formations 
  but 
  little 
  

   was 
  found, 
  and 
  that 
  merely 
  the 
  continuation 
  of 
  the 
  areas 
  flanking 
  the 
  

   Front 
  Eange 
  on 
  the 
  east. 
  Cretaceous, 
  i. 
  e., 
  the 
  lower 
  members 
  thereof, 
  

   is 
  well 
  developed. 
  During 
  the 
  Cretaceous 
  period 
  the 
  Saugre 
  de 
  Cristo 
  

   Eange 
  served 
  as 
  a 
  very 
  effectual 
  barrier, 
  preventing 
  the 
  waters 
  from 
  en- 
  

   tering 
  the 
  western 
  country 
  beyond, 
  and 
  we 
  find 
  therefore 
  no 
  evidence 
  of 
  

   it 
  in 
  San 
  Luis 
  Valley 
  on 
  either 
  side, 
  and 
  do 
  not 
  again 
  meet 
  with 
  the 
  

   formation 
  until 
  we 
  reach 
  the 
  western 
  slope 
  of 
  the 
  Sawatch 
  Eange 
  and 
  the 
  

   Uucompahgre 
  group. 
  Tertiary 
  does 
  not 
  reach 
  our 
  district 
  as 
  far 
  as 
  it 
  has 
  

   herein 
  been 
  described. 
  South 
  of 
  the 
  Spanish 
  Peak 
  country 
  the 
  Post- 
  

   Cretaceous 
  is 
  admirably 
  well 
  developed. 
  Volcanic 
  rocks 
  cover 
  but 
  a 
  

   small 
  area; 
  are 
  of 
  considerable 
  interest 
  however 
  in 
  the 
  northern 
  and 
  

   middle 
  part 
  of 
  the 
  district, 
  where 
  their 
  peculiar 
  character 
  and 
  favorable 
  

   occurrence 
  invites 
  study 
  and 
  comparison. 
  

  

  