﻿372 
  REPORT 
  UNITED 
  STATES 
  GEOLOGICAL 
  SURVEY. 
  

  

  &c., 
  are 
  still 
  more 
  recently 
  introduced 
  names, 
  and 
  therefore, 
  as 
  to 
  their 
  

   location, 
  even 
  less 
  fixed 
  in 
  the 
  people's 
  mind. 
  

  

  In 
  describing 
  the 
  features 
  of 
  this 
  district 
  I 
  have 
  occasionally 
  referred 
  

   to 
  valleys, 
  mountains, 
  and 
  mountain-chains 
  as 
  belonging 
  to 
  first 
  order, 
  

   second 
  order, 
  third 
  order, 
  &g. 
  In 
  the 
  category 
  of 
  first 
  order 
  I 
  include 
  

   such 
  mountain 
  chains 
  or 
  ranges 
  as 
  form 
  either 
  continental 
  water-sheds, 
  

   or, 
  as 
  in 
  the 
  case 
  of 
  the 
  Park 
  Eange, 
  by 
  its 
  great 
  dominating 
  height 
  as 
  

   well 
  as 
  long 
  extent, 
  form 
  also 
  a 
  geographical 
  barrier 
  or 
  subdivision 
  of 
  

   a 
  certain 
  zone. 
  In 
  the 
  second 
  order 
  1 
  would 
  range 
  such 
  mountains 
  as, 
  

   though 
  they 
  may 
  not 
  be 
  any 
  or 
  not 
  much 
  inferior 
  in 
  height 
  to 
  the 
  former, 
  

   are 
  of 
  comparatively 
  short 
  extent, 
  and 
  take 
  no 
  prominent 
  part 
  in 
  subdi- 
  

   viding 
  the 
  country 
  at 
  large 
  into 
  distinct 
  zones, 
  like 
  Kanoska, 
  Tarryall, 
  

   and 
  William 
  Ranges. 
  Among 
  the 
  mountain 
  ridges 
  of 
  the 
  third 
  order 
  I 
  

   would 
  class 
  those 
  that 
  are 
  not 
  simply 
  spur 
  extensions 
  of 
  higher 
  mount- 
  

   ains, 
  but 
  bearing 
  all 
  the 
  characteristics 
  of 
  a 
  detached 
  or 
  distinct 
  range, 
  

   in 
  extent 
  long 
  enough 
  perhaps 
  to 
  bring 
  forth 
  subdivisions 
  of 
  smaller 
  

   zones, 
  as 
  in 
  the 
  caseof 
  Yasquez 
  Ridge, 
  and 
  perhaps 
  Troublesome 
  Ridge. 
  

   We 
  might 
  even 
  recognize 
  a 
  fourth 
  order, 
  such 
  as 
  the 
  parallel 
  Trachyte 
  

   Ridges 
  in 
  the 
  South 
  Park. 
  

  

  Of 
  valleys 
  of 
  first 
  order 
  we 
  have 
  but 
  few, 
  if 
  any, 
  in 
  the 
  whole 
  Rocky 
  

   Mountain 
  districts, 
  as 
  none 
  of 
  them 
  have 
  any 
  broad, 
  expanded, 
  bottom 
  

   area 
  like 
  the 
  large 
  rivers 
  of 
  the 
  East. 
  The 
  first-class 
  valleys 
  in 
  the 
  

   Rocky 
  Mountains 
  are 
  hardly 
  anything 
  but 
  depressions 
  or 
  basins, 
  such 
  

   as 
  those 
  of 
  the 
  Grand 
  River 
  in 
  the 
  Middle 
  Park 
  and 
  the 
  South 
  Platte 
  

   River 
  in 
  the 
  South 
  Park. 
  

  

  For 
  these 
  high 
  altitudes 
  different 
  conditions 
  exist 
  in 
  valleys 
  from 
  

   those 
  in 
  the 
  middle 
  portions 
  of 
  the 
  continent. 
  If 
  we 
  classify 
  the 
  valleys 
  

   of 
  the 
  Rocky 
  Mountains 
  in 
  first, 
  second 
  order, 
  &c., 
  it 
  is 
  done 
  with 
  the 
  pro- 
  

   viso 
  that 
  we 
  have 
  to 
  adopt 
  for 
  this 
  high 
  region 
  a 
  different 
  scale 
  for 
  class- 
  

   ification. 
  Among 
  valleys 
  of 
  first 
  order 
  would 
  necessarily 
  be 
  classed 
  

   such 
  as 
  Grand 
  River 
  while 
  in 
  Middle 
  Park 
  ; 
  Muddy, 
  Blue, 
  and 
  South 
  

   Platte 
  Rivers 
  while 
  in 
  South 
  Park. 
  Valleys 
  of 
  second 
  order 
  might 
  per- 
  

   haps 
  be 
  called 
  such 
  as 
  North 
  Fork 
  of 
  South 
  Platte 
  River, 
  Tarryall, 
  Fra- 
  

   zier, 
  and 
  Williams 
  Rivers. 
  Third 
  order, 
  such 
  as 
  Twin 
  Creek, 
  Manitou, 
  

   Deer, 
  and 
  Elk 
  Creeks. 
  Valleys 
  like 
  Monument 
  and 
  Plum 
  Creeks 
  be- 
  

   long 
  already 
  partially 
  to 
  the 
  plains. 
  No 
  valley 
  form 
  accompanies 
  the 
  

   eastern-slope 
  drainage, 
  all 
  the 
  rivers 
  and 
  streams 
  flowing 
  in 
  caSons, 
  and 
  

   assuming 
  valley 
  features 
  only 
  where 
  they 
  enter 
  the 
  plains 
  like 
  Platte 
  

   River. 
  

  

  With 
  this 
  simple 
  explanation 
  of 
  the 
  plan 
  of 
  my 
  study, 
  I 
  will 
  proceed 
  

   directly 
  to 
  the 
  consideration 
  of 
  the 
  features 
  themselves, 
  beginning 
  with 
  

   the 
  main 
  or 
  Colorado 
  divide. 
  

  

  