﻿CHAPTER 
  II. 
  

  

  SAN 
  LUIS 
  VALLEY. 
  

  

  During 
  the 
  years 
  1873 
  aud 
  1874, 
  our 
  division 
  of 
  the 
  United 
  States 
  Geo- 
  

   logical 
  Survey 
  examined 
  and 
  mapped 
  the 
  northern 
  portion 
  of 
  San 
  Luis 
  

   Valley. 
  Though 
  much 
  information 
  was 
  elicited 
  during 
  the 
  progress 
  of 
  

   our 
  work, 
  it 
  soon 
  became 
  apparent 
  that 
  but 
  little 
  could 
  be 
  done 
  toward 
  

   a 
  final 
  solution 
  of 
  this 
  problem 
  until 
  the 
  southern 
  end 
  of 
  the 
  valley 
  had 
  

   been 
  explored. 
  Numerous 
  questions 
  enter 
  into 
  consideration 
  regarding 
  

   the 
  genesis 
  and 
  early 
  condition 
  of 
  this 
  depression. 
  The 
  work 
  referred 
  

   to 
  above 
  was 
  accoraplished 
  during 
  1875, 
  and 
  we 
  are 
  now 
  able 
  to 
  discuss 
  

   the 
  valley 
  aud 
  its 
  immediate 
  surroundings 
  as 
  a 
  whole. 
  In 
  order 
  to 
  pre- 
  

   sent 
  the 
  facts 
  that 
  have 
  been 
  gathered 
  in 
  a 
  clearer 
  and 
  more 
  connected 
  

   manner, 
  I 
  shall 
  discuss 
  the 
  northern 
  as 
  well 
  as 
  the 
  southern 
  parts, 
  at 
  

   the 
  risk, 
  even, 
  of 
  repeating 
  what 
  may 
  have 
  been 
  said 
  with 
  regard 
  to 
  the 
  

   former 
  in 
  previous 
  reports. 
  Ai)ait 
  from 
  the 
  purely 
  scientific 
  interest 
  in- 
  

   herent 
  in 
  the 
  geological 
  history 
  of 
  San 
  Luis 
  Valley, 
  the 
  results 
  we 
  have 
  

   obtained 
  have 
  a 
  practical 
  bearing 
  upon 
  the 
  conversion 
  of 
  waste 
  laud 
  

   into 
  productive 
  soil. 
  In 
  order 
  to 
  speak 
  positively 
  in 
  reference 
  to 
  this 
  

   point, 
  in 
  order 
  to 
  demonstrate 
  the 
  extent 
  of 
  improvements 
  thus 
  to 
  be 
  

   made, 
  a 
  survey 
  upon 
  a 
  larger 
  scale 
  than 
  ours 
  would 
  be 
  required, 
  and 
  it 
  

   is 
  with 
  this 
  lirefacing 
  remark 
  that 
  any 
  suggestions 
  are 
  made. 
  

  

  Crossing 
  Poncho 
  Pass 
  from 
  the 
  north, 
  we 
  enter 
  Homan's 
  Park, 
  the 
  

   northern 
  end 
  of 
  San 
  Luis 
  Valley. 
  Low, 
  rolling 
  bluffs 
  present 
  a 
  more 
  

   broken 
  appearance 
  of 
  the 
  country, 
  which 
  fully 
  justifies 
  the 
  separation 
  

   by 
  a 
  distinguishing 
  name. 
  On 
  either 
  side 
  mountains 
  of 
  considerable 
  

   altitude 
  inclose 
  the 
  park. 
  A 
  terminal 
  range 
  of 
  the 
  Sawatch 
  Mountains 
  

   is 
  on 
  the 
  west; 
  the 
  Sangre 
  de 
  Cristo 
  Range 
  on 
  the 
  east. 
  Through 
  the 
  

   park 
  runs 
  San 
  Luis 
  Creek 
  in 
  a 
  southerly 
  direction. 
  A 
  short 
  distance 
  

   below 
  the 
  junction 
  of 
  this 
  aud 
  Kerber 
  Creek 
  the 
  valley 
  proper 
  com- 
  

   mences. 
  A 
  vast 
  expanse 
  of 
  level 
  country 
  stretches 
  out 
  to 
  the 
  south- 
  

   ward, 
  widening 
  in 
  that 
  direction. 
  Sand 
  and 
  alkali 
  abound. 
  All 
  along 
  

   the 
  eastern 
  border 
  of 
  the 
  valley 
  the 
  Sangre 
  de 
  Cristo 
  Range 
  follows 
  its 
  

   course, 
  culminating 
  frequently 
  in 
  peaks 
  that 
  reach 
  over 
  14,000 
  ieet 
  ele- 
  

   vation. 
  Toward 
  the 
  main 
  passes 
  that 
  cut 
  this 
  range, 
  in 
  the 
  vicinity 
  of 
  

   Port 
  Garland 
  the 
  valley 
  widens 
  considerably, 
  and 
  retains 
  for 
  some 
  dis- 
  

   tance 
  farther 
  south 
  a 
  width 
  of 
  about 
  forty 
  miles 
  on 
  average. 
  On 
  the 
  

   west 
  the 
  long-continued 
  Sawatch 
  Range, 
  with 
  its 
  high 
  volcanic 
  regions, 
  

   serves 
  as 
  a 
  boundary 
  for 
  the 
  valle\. 
  It 
  falls 
  off 
  more 
  steeply 
  farther 
  

   north 
  than 
  in 
  the 
  southern 
  portion, 
  for 
  reasons 
  below 
  to 
  be 
  given, 
  lu 
  

   the 
  vicinity 
  of 
  Rios 
  Conejos 
  and 
  Culebra 
  bluffs 
  rise 
  in 
  the 
  valley 
  to 
  a 
  

   relative 
  altitude 
  of 
  1,400 
  feet, 
  which 
  break 
  the 
  continuous 
  uuiforuuty 
  of 
  

   its 
  level. 
  Farther 
  south 
  still, 
  the 
  plain 
  gradually 
  grows 
  more 
  narrow, 
  

   the 
  mountains 
  on 
  both 
  east 
  and 
  west 
  sides 
  approach 
  each 
  other, 
  and 
  

   at 
  about 
  north 
  latitude 
  30° 
  45', 
  or 
  fifteen 
  miles 
  below 
  the 
  southern 
  

   boundary 
  of 
  Colorado, 
  the 
  valley 
  may 
  be 
  considered 
  as 
  having 
  come 
  to 
  

   an 
  end. 
  

  

  140 
  

  

  