﻿,PEALE.]- 
  UNAWEEP 
  CANON 
  SALT 
  MOUNTAINS. 
  59 
  

  

  Uncompahgre 
  plateau. 
  The 
  present 
  stream 
  flowing 
  through 
  it 
  is 
  inade- 
  

   quate 
  to 
  explain 
  the 
  erosion 
  of 
  this 
  part 
  ot 
  the 
  canon. 
  

  

  'M 
  The 
  general 
  slope 
  of 
  the 
  country, 
  as 
  determined 
  by 
  thedirection 
  

   of"th'e 
  Grand 
  and 
  Gunnison 
  Rivers, 
  was 
  to 
  the 
  westward. 
  We 
  would, 
  

   therefore, 
  naturally 
  expect 
  the 
  stream 
  to 
  flow 
  to 
  the 
  westward. 
  

  

  3d. 
  The 
  probability 
  that 
  the 
  caiion 
  was 
  cut 
  slowly 
  as 
  the 
  Uncorapali- 
  

  

  ere 
  plateau 
  rose. 
  , 
  ^ 
  i 
  /-> 
  • 
  

  

  Xow 
  let 
  us 
  consider 
  the 
  probability 
  that 
  the 
  Grand 
  or 
  Gunnison 
  

   flowed 
  throughUnaweep 
  Caiion. 
  Of 
  the 
  two 
  streams, 
  the 
  Gunnison 
  is 
  

   the 
  one 
  that 
  seems 
  to 
  have 
  the 
  preference. 
  Where 
  East 
  Creek 
  turns 
  

   to 
  the 
  northward 
  there 
  is 
  a 
  broad 
  valley 
  extending 
  southward 
  and 
  east- 
  

   ward 
  which 
  seems 
  to 
  mark 
  the 
  continuation 
  of 
  the 
  canon, 
  it 
  being 
  

   much 
  wider 
  and 
  extending 
  to 
  the 
  Gunnison. 
  The 
  valley, 
  however, 
  as 
  

   well 
  as 
  the 
  caiion 
  of 
  East 
  Creek, 
  is 
  in 
  soft 
  sedimentaries, 
  and 
  very 
  

   little 
  can 
  be 
  argued 
  as 
  to 
  past 
  conditions 
  from 
  what 
  we 
  see 
  now. 
  _ 
  

  

  Just 
  east 
  of 
  the 
  crest 
  of 
  the 
  Uncompahgre 
  plateau 
  the 
  canon 
  is 
  

   broadest 
  and 
  deepest. 
  The 
  map 
  suggests 
  to 
  us 
  the 
  idea 
  that 
  it 
  once 
  

   was 
  occupied 
  by 
  a 
  lake. 
  If 
  the 
  Gunnison 
  flowed 
  to 
  the 
  west 
  through 
  

   the 
  caiion, 
  we 
  niay 
  suppose 
  that 
  the 
  plateau 
  rose 
  faster 
  than 
  the 
  cutang 
  

   of 
  the 
  canon 
  progressed. 
  This 
  would 
  cause 
  a 
  lake 
  to 
  be 
  formed, 
  with 
  

   the 
  crest 
  as 
  its 
  barrier 
  on 
  the 
  west. 
  Next, 
  we 
  have 
  to 
  suppose 
  this 
  bar- 
  

   rier 
  cut 
  awav 
  gradually 
  and 
  the 
  lake 
  drained. 
  Following 
  this, 
  also, 
  we 
  

   must 
  suppose 
  the 
  elevation 
  of 
  the 
  plateau 
  continued 
  with 
  an 
  accele- 
  

   rated 
  movement 
  to 
  allow 
  the 
  river 
  to 
  take 
  a 
  new 
  course— 
  the 
  present 
  

   course 
  If 
  not, 
  we 
  must 
  suppose 
  the 
  present 
  course 
  to 
  have 
  been 
  deter- 
  

   mined 
  bv 
  a 
  new 
  outlet 
  to 
  the 
  lake, 
  and 
  the 
  latter 
  drained 
  in 
  that 
  direc- 
  

   tion 
  rather 
  than 
  toward 
  the 
  Dolores, 
  in 
  the 
  ancient 
  course 
  of 
  the 
  

   stream. 
  The 
  l^ike, 
  if 
  it 
  ever 
  existed, 
  must 
  have 
  spread 
  over 
  a 
  wide 
  

   extent 
  of 
  countrv 
  ; 
  and 
  we 
  are 
  still 
  left 
  in 
  doubt 
  as 
  to 
  the 
  formation 
  of 
  

   the 
  gorge, 
  as 
  the 
  lake 
  would 
  evidently 
  not 
  be 
  limited 
  by 
  the 
  walls 
  ot 
  

   the 
  caiiSn. 
  It 
  is 
  hard 
  to 
  imagine 
  the 
  lake 
  cutting 
  the 
  canon. 
  If 
  the 
  

   lake 
  were 
  confined 
  within 
  the 
  present 
  walls 
  of 
  the 
  canon, 
  we 
  ought 
  to 
  

   find 
  at 
  least 
  traces 
  of 
  its 
  sediments, 
  which 
  we 
  do 
  not. 
  All 
  that 
  can 
  be 
  

   said 
  at 
  present 
  is 
  that 
  there 
  is 
  presumptive 
  evidence 
  that 
  the 
  stream 
  

   flowed 
  to 
  the 
  westward, 
  and 
  was 
  deflected 
  from 
  its 
  course 
  by 
  the 
  con- 
  

   tinued 
  upheaval 
  of 
  the 
  Uncompahgre 
  plateau. 
  Future 
  close 
  study 
  ot 
  

   the 
  caiion 
  and 
  the 
  surrounding 
  country 
  will 
  doubtless 
  give 
  more 
  facts 
  

   from 
  which 
  details 
  can 
  be 
  determined, 
  but 
  the 
  view 
  stated 
  above 
  will 
  

   probably 
  be 
  the 
  general 
  idea 
  which 
  they 
  will 
  confirm. 
  

  

  SIEREA 
  LA 
  SAL 
  AND 
  GRAND 
  RIVER. 
  

  

  The 
  first 
  thing 
  we 
  notice 
  in 
  looking 
  at 
  the 
  map 
  of 
  the 
  Salt 
  Mount- 
  

   ains 
  is 
  the 
  radiation 
  in 
  the 
  drainage 
  of 
  which 
  the 
  mountain 
  mass 
  is 
  the 
  

   center. 
  The 
  entire 
  area 
  includes 
  about 
  1,300 
  square 
  miles. 
  On 
  the 
  

   southeast 
  and 
  northeast 
  the 
  creeks 
  are 
  tributary 
  to 
  the 
  Dolores 
  Kiver, 
  

   while 
  on 
  the 
  north 
  and 
  west 
  they 
  flow 
  to 
  the 
  Grand. 
  

  

  The 
  Salt 
  Mountains 
  consist 
  of 
  about 
  thirty 
  peaks, 
  forming 
  a 
  range 
  

   about 
  15 
  miles 
  in 
  length 
  and 
  about 
  5 
  miles 
  wide. 
  The 
  axis 
  ot 
  the 
  

   range 
  is 
  about 
  north 
  and 
  south. 
  The 
  peaks 
  range 
  m 
  elevation 
  from 
  

   11 
  800 
  feet 
  to 
  12,980 
  feet, 
  rising 
  8,000 
  to 
  8,500 
  feet 
  above 
  the 
  level 
  ot 
  the 
  

   Dolores 
  and 
  Grand 
  Rivers. 
  The 
  mountains 
  are 
  of 
  porphyritic 
  trachyte, 
  

   and 
  they 
  are-eruptive, 
  although 
  their 
  present 
  form 
  is 
  largely 
  the 
  result 
  

   of 
  subsequent 
  erosion. 
  Powell* 
  refers 
  to 
  the 
  fact 
  that 
  many 
  of 
  the 
  iso- 
  

   lated 
  eruptive 
  mountains 
  in 
  the 
  Colorado 
  Elver 
  region 
  west 
  ot 
  the 
  region 
  

  

  * 
  Exploration 
  of 
  the 
  Colorado 
  River 
  of 
  the 
  V^^est, 
  p. 
  200-203. 
  

  

  