﻿ENDLicH.] 
  APPENDIX 
  — 
  ANCIENT 
  GLACIERS. 
  219 
  

  

  existence 
  of 
  glaciers 
  — 
  and 
  we 
  have 
  the 
  undoubted 
  evidence 
  of 
  their 
  

   former 
  presence 
  — 
  there 
  are 
  but 
  few 
  localities 
  in 
  Southern 
  Colorado 
  that 
  

   would 
  be 
  so 
  favorable 
  to 
  their 
  formation. 
  An 
  elevated 
  plateau, 
  a 
  large 
  

   portion 
  of 
  which 
  is 
  above 
  timber-line, 
  stretches 
  nearly 
  horizontally 
  from 
  

   northwest 
  to 
  southeast, 
  cut 
  at 
  right 
  angles 
  to 
  its 
  strike 
  by 
  deep 
  caiions. 
  

   Precipitation 
  of 
  moisture 
  is 
  there, 
  at 
  least 
  at 
  the 
  present 
  time, 
  very 
  

   plentiful, 
  and 
  nothing 
  would 
  prevent 
  the 
  formation 
  of 
  large 
  masses 
  of 
  

   ice. 
  After 
  descending 
  into 
  the 
  lower 
  valleys, 
  the 
  glaciers 
  probably 
  

   would 
  have 
  succumbed 
  to 
  the 
  change 
  of 
  temperature, 
  as 
  there 
  is 
  about 
  

   5,000 
  feet 
  difference 
  of 
  elevation 
  along 
  the 
  edge 
  of 
  that 
  volcanic 
  plateau 
  

   and 
  the 
  valleys 
  immediately 
  west 
  of 
  it. 
  This, 
  of 
  course, 
  may 
  account 
  

   for 
  the 
  fact 
  that 
  so 
  few 
  glaciers 
  descended 
  as 
  low 
  as 
  the 
  two 
  above 
  de- 
  

   scribed 
  (8,000 
  feet 
  above 
  sea-level). 
  

  

  Of 
  by 
  far 
  greater 
  extent 
  was 
  the 
  glacier 
  occupying 
  a 
  position 
  on 
  the 
  

   summit 
  of 
  the 
  volcanic 
  plateau, 
  at 
  the 
  headwaters 
  of 
  Eio 
  Conejos 
  and 
  

   Eio 
  Chama. 
  Eiding 
  up 
  this 
  latter 
  river 
  the 
  first 
  indications 
  of 
  glacial 
  

   action 
  were 
  observed 
  at 
  an 
  altitude 
  of 
  8,450 
  feet. 
  The 
  surrounding 
  rock 
  

   was 
  trachyte 
  and 
  trachytic 
  conglomerate, 
  strewn 
  upon 
  which 
  erratic 
  

   bowlders 
  of 
  mica-schist 
  and 
  gneiss 
  were 
  found. 
  Irregular 
  knolls 
  of 
  

   erratic 
  material 
  along 
  the 
  cai5on 
  gave 
  evidence 
  of 
  morainal 
  deposits. 
  

   Large 
  quantities 
  of 
  earth 
  and 
  gravel, 
  obtained 
  partly 
  from 
  the 
  meta- 
  

   morphic 
  rocks, 
  whose 
  site 
  we 
  had 
  not 
  yet 
  discovered, 
  partly 
  from 
  the 
  

   trachyte 
  and 
  conglomerate, 
  formed 
  small 
  hills, 
  scattered 
  across 
  the 
  nar- 
  

   row 
  valley 
  without 
  order. 
  From 
  the 
  land 
  and 
  rock 
  slides 
  near 
  the 
  caiion- 
  

   walls 
  they 
  were 
  readily 
  distinguishable. 
  For 
  the 
  distance 
  of 
  about 
  five 
  

   miles 
  this 
  continued, 
  until 
  the 
  caSou 
  closed 
  in 
  very 
  suddenly. 
  This 
  

   occurrence 
  is 
  the 
  most 
  southerly 
  one 
  that 
  i 
  have 
  observed 
  in 
  Colorado, 
  

   reaching 
  south 
  of 
  north 
  latitude 
  37° 
  into 
  New 
  Mexico. 
  Examining 
  a 
  

   wall 
  that 
  seemed 
  to 
  shut 
  every 
  egress 
  off 
  completely, 
  the 
  metamorphic 
  

   rocks 
  were 
  discovered 
  inpositu^ 
  and 
  were 
  found 
  to 
  be 
  the 
  same 
  that 
  fur- 
  

   nished 
  the 
  erratic 
  bowlders. 
  It 
  was 
  seen 
  that 
  the 
  glaciers 
  transporting 
  

   the 
  material 
  had 
  descended 
  2,700 
  feet 
  from 
  the 
  summit 
  of 
  the 
  plateau 
  

   from 
  the 
  northwest 
  in 
  a 
  horizontal 
  distance 
  of 
  about 
  three 
  miles, 
  and 
  

   then 
  had 
  pushed 
  before 
  it 
  the 
  material 
  that 
  had 
  accumulated 
  for 
  age.s 
  

   in 
  the 
  narrow 
  valley 
  below. 
  Polished 
  rocks 
  m 
  j^osiiw 
  and 
  striation 
  of 
  

   the 
  same 
  gave 
  evidence 
  of 
  the 
  course 
  followed 
  by 
  the 
  glacier. 
  Probably 
  

   one 
  or 
  two 
  smaller 
  branches 
  of 
  the 
  glacier 
  above 
  descended 
  from 
  the 
  

   northeast, 
  but 
  the 
  nature 
  of 
  the 
  rock 
  is 
  such 
  that 
  striation 
  or 
  polish 
  

   would 
  there 
  soon 
  have 
  vanished. 
  Small 
  outcrops 
  of 
  granite 
  at 
  that 
  

   locality 
  show 
  the 
  thickness 
  of 
  the 
  volcanic 
  beds 
  to 
  be 
  about 
  3,000 
  feet. 
  

   Although 
  the 
  lower 
  and 
  upper 
  beds 
  of 
  the 
  volcanic 
  rock 
  are 
  hard 
  and 
  

   firm, 
  the 
  middle 
  ones 
  are 
  composed 
  of 
  conglomerate, 
  which 
  readily 
  

   yields 
  to 
  erosive 
  agents. 
  Farther 
  north 
  this 
  becomes 
  more 
  apparent 
  

   still. 
  

  

  Ascending 
  to 
  the 
  plateau, 
  evidences 
  of 
  glaciers 
  are 
  found 
  in 
  the 
  pres- 
  

   ence 
  of 
  small 
  shallow 
  lakes 
  within 
  the 
  timber-line. 
  On 
  the 
  plateau 
  

   itself, 
  just 
  at 
  the 
  headwaters 
  of 
  Eio 
  Chama, 
  the 
  greater 
  portion 
  of 
  the 
  

   volcanic 
  strata 
  is 
  exposed 
  to 
  view 
  without 
  having 
  formed 
  any 
  soil. 
  

   Striation 
  and 
  polishing 
  of 
  the 
  most 
  beautiful 
  type 
  extends 
  from 
  here 
  

   (station 
  84, 
  about 
  11,800 
  feet) 
  for 
  four 
  miles 
  farther 
  north, 
  along 
  the 
  

   headwaters 
  of 
  the 
  Eio 
  Conejos. 
  At 
  this 
  place, 
  too, 
  there 
  is 
  evidence 
  of 
  

   a 
  " 
  drop 
  '■ 
  of 
  about 
  400 
  to 
  500 
  feet 
  vertical 
  distance. 
  But 
  very 
  little 
  lateral 
  

   displacement 
  has 
  occurred 
  in 
  consequence 
  thereof. 
  Near 
  station 
  84, 
  the 
  

   stride 
  lead 
  toward 
  the 
  canon 
  of 
  the 
  Chama 
  south. 
  From 
  the 
  fine 
  striae, 
  

   the 
  diameter 
  of 
  a 
  hair 
  on 
  a 
  highly 
  polished 
  suiiace, 
  these 
  witnesses 
  of 
  

   former 
  glacial 
  motion 
  occur, 
  increasing 
  to 
  grooves 
  3 
  and 
  4 
  inches 
  wide 
  

  

  