﻿HATDEN.l 
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  THE 
  SECRETARY. 
  3 
  

  

  tain 
  coal 
  at 
  a 
  number 
  of 
  points. 
  It 
  will 
  not 
  be 
  possible 
  to 
  determine 
  

   their 
  geological 
  age 
  with 
  any 
  degree 
  of 
  certainty 
  until 
  careful 
  compari- 
  

   sons 
  of 
  the 
  parallel 
  formations 
  observed 
  by 
  Mr. 
  Holmes 
  and 
  Dr. 
  Peale 
  

   can 
  be 
  made. 
  The 
  absence 
  of 
  fossils 
  is 
  greatly 
  to 
  be 
  regretted, 
  but 
  none 
  

   were 
  found, 
  although 
  many 
  square 
  miles 
  were 
  traversed 
  containing 
  the 
  

   series. 
  Speaking 
  with 
  the 
  reserve 
  that 
  imperfect 
  comparison 
  of 
  the 
  

   notes 
  taken 
  dictates, 
  it 
  would 
  appear 
  that 
  the 
  Trinidad 
  coal-bearing 
  series 
  

   is 
  parallel 
  to 
  this 
  one. 
  

  

  After 
  having 
  completed 
  the 
  survey 
  of 
  this 
  lower 
  region 
  along 
  the 
  Eio 
  

   San 
  Juan 
  and 
  its 
  tributaries, 
  the 
  work 
  was 
  continued 
  to 
  the 
  extension 
  

   of 
  the 
  La 
  Plata 
  Mountains. 
  Here 
  again 
  volcanic 
  rocks 
  were 
  met 
  with, 
  

   identical 
  in 
  every 
  respect 
  with 
  those 
  farther 
  north 
  and 
  west. 
  Here, 
  as 
  

   well 
  as 
  previously 
  on 
  the 
  headwaters 
  of 
  the 
  Pinos 
  and 
  Piedra, 
  evidence 
  

   of 
  former 
  glaciers 
  was 
  found. 
  Considerable 
  areas 
  showed 
  the 
  grooving 
  

   and 
  striation 
  of 
  rocks 
  in 
  positu, 
  produced 
  by 
  the 
  motion 
  of 
  ice 
  and 
  

   bowlders. 
  Deep 
  canons 
  were 
  cut 
  into, 
  volcanic 
  conglomerate 
  occurring 
  

   there, 
  that 
  had 
  not 
  preserved 
  the 
  grooving 
  and 
  striation, 
  however, 
  owing 
  

   to 
  the 
  rapidity 
  with 
  which 
  it 
  yields 
  to 
  the 
  effect 
  of 
  atmospheric 
  influ- 
  

   ences. 
  A 
  gentle 
  slope 
  eastward 
  of 
  the 
  volcanic 
  rocks, 
  that 
  there 
  reached 
  

   to 
  the 
  youngest 
  member 
  of 
  the 
  group, 
  basalt, 
  gradually 
  merged 
  into 
  

   the 
  San 
  Luis 
  Valley. 
  Affected 
  by 
  local 
  basaltic 
  eruptions, 
  as 
  well 
  as 
  by 
  

   the 
  easterly 
  dip 
  of 
  the 
  volcanic 
  beds, 
  the 
  drainage 
  on 
  the 
  west 
  side 
  of 
  

   this 
  valley 
  presents 
  some 
  interesting 
  features, 
  consisting 
  in 
  sudden 
  curves 
  

   northward. 
  Northward, 
  the 
  unbroken 
  flows 
  of 
  basalt 
  continue 
  on 
  the 
  

   west 
  side 
  of 
  the 
  valley 
  until 
  Rio 
  Alamosa 
  is 
  reached, 
  where 
  they 
  end 
  

   and 
  drift 
  begins. 
  A 
  number 
  of 
  volcanic 
  bluffs, 
  trending 
  nearly 
  north 
  

   and 
  south, 
  separate 
  this 
  portion 
  from 
  the 
  valley 
  through 
  which 
  the 
  Rio 
  

   Grande 
  runs 
  after 
  making 
  its 
  turn 
  southward 
  west 
  of 
  Fort 
  Garland. 
  

   This 
  region, 
  geologically, 
  is 
  more 
  interesting 
  than 
  the 
  western 
  one, 
  on 
  

   account 
  of 
  the 
  evidence 
  furnished 
  demonstrating 
  the 
  existence 
  of 
  two 
  

   very 
  large 
  lakes 
  at 
  the 
  close 
  of 
  the 
  volcanic 
  activity 
  there. 
  The 
  two 
  

   were 
  connected 
  by 
  a 
  narrow 
  strip 
  of 
  water 
  south 
  of 
  Fort 
  Garland, 
  and 
  

   the 
  lower 
  one 
  extended 
  southward 
  nearly 
  to 
  the 
  Rio 
  Colorado. 
  At 
  that 
  

   time, 
  too, 
  the 
  course 
  of 
  the 
  Rio 
  Grande 
  was 
  different 
  from 
  its 
  present 
  

   one. 
  By 
  the 
  formation 
  of 
  a 
  narrow 
  canon 
  in 
  the 
  basaltic 
  beds, 
  the 
  course 
  

   of 
  the 
  river 
  was 
  deflected, 
  the 
  lakes 
  drained, 
  and 
  the 
  topography 
  left 
  very 
  

   nearly 
  in 
  the 
  shape 
  we 
  now 
  observe 
  it. 
  The 
  accurate 
  determinition 
  of 
  

   all 
  the 
  points 
  connected 
  with 
  the 
  existence 
  of 
  these 
  lakes 
  offers 
  no 
  ma- 
  

   terial 
  obstacle, 
  but 
  requires 
  by 
  far 
  more 
  time 
  than 
  could 
  be 
  bestowed 
  

   upon 
  it 
  in 
  the 
  regular 
  course 
  of 
  the 
  survey. 
  

  

  Separating 
  the 
  eastern 
  foothills 
  and 
  the 
  great 
  plains 
  from 
  San 
  Luis 
  

   Valley 
  is 
  the 
  southern 
  continuation 
  of 
  the 
  Sangre 
  de 
  Cristo 
  Range. 
  

   Several 
  peaks 
  of 
  this 
  range 
  rise 
  to 
  an 
  elevation 
  of 
  nearly 
  14,000 
  feet, 
  

   while 
  many 
  of 
  them 
  reach 
  13,000 
  feet 
  above 
  sea-level. 
  Here 
  again 
  meta- 
  

   morphic 
  rocks 
  set 
  in, 
  containing 
  indications 
  of 
  metalliferous 
  veins. 
  

   Sedimentary 
  beds, 
  belonging 
  to 
  the 
  Carboniferous 
  and 
  Cretaceous 
  ages, 
  

  

  