﻿ENDLicH.l 
  SA 
  WATCH 
  EANGE 
  METAMOliPHICS. 
  165 
  

  

  but 
  partially 
  covered 
  by 
  the 
  volcanic 
  beds, 
  or 
  were 
  covered 
  with 
  so 
  thin 
  

   a 
  layer 
  that 
  this 
  readily 
  yielded 
  to 
  erosion 
  and 
  was 
  carried 
  off, 
  thus 
  ex- 
  

   posiug 
  the 
  older 
  formations. 
  Near 
  station 
  95 
  the 
  trachytic 
  area 
  shows 
  

   its 
  smallest 
  width 
  along 
  the 
  entire 
  range 
  (so 
  far 
  as 
  treated 
  of 
  in 
  this 
  

   chapter), 
  and 
  it 
  is 
  here 
  that 
  the 
  metamorphic 
  formations 
  appear. 
  Several 
  

   small 
  outcrops 
  were 
  observed 
  farther 
  north, 
  in 
  deep 
  canons, 
  where 
  the 
  

   superincumbent 
  volcanics 
  had 
  been 
  removed. 
  This 
  was 
  aided, 
  in 
  two 
  

   instances 
  at 
  least, 
  by 
  the 
  agency 
  of 
  glaciers. 
  Evidences 
  of 
  the 
  latter 
  

   were 
  observed 
  near 
  station 
  94, 
  at 
  the 
  western 
  edge 
  of 
  the 
  metamorphic 
  

   outcrop, 
  but, 
  so 
  far 
  as 
  could 
  be 
  determined, 
  they 
  were 
  of 
  small 
  extent 
  

   only. 
  Drift 
  found 
  20 
  to 
  30 
  miles 
  farther 
  west, 
  on 
  the 
  summits 
  of 
  Ter- 
  

   tiary 
  bluffs, 
  could 
  have 
  originated 
  nowhere 
  but 
  at 
  this 
  locality. 
  It 
  is 
  

   difficult 
  to 
  decide, 
  however, 
  whether 
  it 
  was 
  transported 
  to 
  those 
  places 
  

   by 
  the 
  agency 
  of 
  water 
  or 
  ice. 
  

  

  Station 
  95 
  is 
  located 
  on 
  a 
  north 
  to 
  south 
  granitic 
  ridge, 
  at 
  an 
  eleva- 
  

   tion 
  of 
  10,373 
  feet. 
  It 
  is 
  the 
  first 
  of 
  the 
  continuous 
  metamorphic 
  out- 
  

   crop 
  that 
  extends 
  from 
  there 
  westward. 
  Throughout 
  the 
  region 
  the 
  rem- 
  

   nants 
  of 
  trachyte 
  superincumbent 
  have 
  the 
  usual 
  easterly 
  dip 
  of 
  6° 
  to 
  

   SO, 
  but 
  the 
  metamorphics 
  show 
  an 
  entirely 
  different 
  one. 
  Following 
  

   down 
  the 
  Eio 
  Brazos, 
  we 
  remain 
  in 
  coarse-grained, 
  light-red 
  granite, 
  

   until, 
  southeast 
  of 
  station 
  94, 
  we 
  reach 
  the 
  older, 
  lower 
  strata 
  and 
  find 
  

   them 
  to 
  consist 
  of 
  quartzite. 
  Here 
  the 
  Brazos 
  runs 
  through 
  a 
  deep, 
  

   impassable 
  canon, 
  walled 
  in 
  on 
  either 
  side 
  by 
  vertical, 
  quartzitic 
  strata. 
  

   Station 
  94 
  is 
  located 
  upon 
  these, 
  just 
  north 
  of 
  the 
  river, 
  at 
  an 
  altitude 
  

   of 
  10,603 
  feet. 
  Here 
  the 
  quartzite 
  occurs 
  in 
  a 
  number 
  of 
  varieties. 
  

   From 
  the 
  pure 
  white, 
  granular 
  quartzite 
  it 
  changes 
  into 
  grey, 
  while 
  

   other 
  strata 
  show 
  slight 
  admixtures 
  of 
  mica. 
  Local 
  accumulations 
  of 
  the 
  

   latter 
  take 
  place 
  in 
  certain 
  strata, 
  producing 
  a 
  micaceous 
  schist. 
  Between 
  

   stations 
  94 
  and 
  93 
  the 
  junction 
  of 
  the 
  superincumbent 
  trachyte 
  and 
  the 
  

   metamorphic 
  quartzite 
  is 
  sharply 
  defined. 
  South 
  of 
  these 
  stations 
  (be- 
  

   yond 
  the 
  limits 
  of 
  our 
  district) 
  trachyte 
  again 
  sets 
  in, 
  covering, 
  as 
  farther 
  

   north, 
  the 
  metamorphic 
  strata. 
  Is'ear 
  station 
  94 
  the 
  evidences 
  of 
  glacial 
  

   action 
  were 
  observed. 
  They 
  consist 
  in 
  the 
  rounding 
  off 
  and 
  polishing 
  of 
  

   quartzitic 
  beds 
  iJipositu. 
  Small 
  lakes 
  and 
  ponds 
  have 
  been 
  formed 
  in 
  the 
  

   shallow 
  excavations 
  produced 
  in 
  iiart 
  by 
  the 
  moving 
  ice. 
  Apparently 
  

   the 
  ice 
  moved 
  downward 
  into 
  the 
  present 
  narrow 
  caiiou 
  of 
  the 
  Brazos, 
  

   but 
  it 
  is 
  highly 
  improbable 
  that 
  ice 
  could 
  have 
  cut 
  that 
  narroiw 
  gorge 
  for 
  

   a 
  depth 
  of 
  more 
  than 
  2,000 
  feet. 
  The 
  latter 
  appears 
  to 
  be 
  a 
  caiion 
  of 
  sepa- 
  

   ration, 
  through 
  which 
  the 
  river 
  found 
  its 
  course 
  after 
  it 
  had 
  been 
  formed. 
  

   Should 
  the 
  glaciers 
  have 
  existed 
  farther 
  south 
  and 
  have 
  been 
  of 
  very 
  

   great 
  extent, 
  their 
  presence 
  would 
  go 
  far 
  toward 
  explaining 
  the 
  occur- 
  

   rence 
  of 
  drift 
  20 
  miles 
  west 
  that 
  has 
  been 
  mentioned 
  above. 
  Viewed 
  

   from 
  the 
  west, 
  from 
  the 
  low 
  valley 
  of 
  the 
  Tierra 
  Amarilla 
  settlement, 
  

   the 
  Brazos 
  Canon 
  has 
  an 
  imposing 
  effect. 
  Dark 
  vertical 
  walls, 
  not 
  un- 
  

   like 
  in 
  general 
  appearance 
  to 
  those 
  of 
  the 
  Yosemite 
  Valley, 
  inclose 
  the 
  

   rushing 
  stream 
  that 
  with 
  steep 
  fall 
  enters 
  the 
  valley 
  at 
  the 
  base 
  of 
  the 
  

   high 
  walls 
  inclosing 
  it. 
  Station 
  94 
  rises 
  high 
  above 
  the 
  depression 
  

   below, 
  and 
  in 
  its 
  outlines 
  already 
  denotes 
  the 
  fact 
  of 
  it 
  being 
  composed 
  

   of 
  a 
  material 
  different 
  from 
  the 
  surrounding 
  volcanics. 
  It 
  would 
  be 
  of 
  

   interest 
  to 
  follow 
  the 
  continuation 
  of 
  the 
  metamorphic 
  outcrop 
  south- 
  

   ward, 
  as 
  there 
  more 
  definite 
  features 
  might 
  be 
  observed. 
  

  

  A 
  section 
  (Section 
  IX) 
  taken 
  from 
  station 
  94 
  to 
  station 
  99, 
  at 
  the 
  western 
  

   edge 
  of 
  San 
  Luis 
  Valley, 
  runs 
  about 
  northeast. 
  Slight 
  variations 
  have 
  

   been 
  made 
  from 
  the 
  straight 
  line, 
  in 
  order 
  to 
  introduce 
  those 
  features 
  

   that 
  are 
  most 
  characteristic 
  to 
  the 
  region. 
  On 
  the 
  western 
  slope, 
  from 
  

   stati'on 
  94 
  downward, 
  we 
  find 
  the 
  Cretaceous 
  beds 
  belonging 
  to 
  the 
  Da- 
  

  

  