﻿J. 
  D. 
  Dana 
  — 
  Features 
  of 
  non-volcanic 
  Igneous 
  Ejections. 
  85 
  

  

  The 
  southern 
  wall 
  of 
  the 
  dike 
  is 
  the 
  roof 
  of 
  the 
  cave 
  ; 
  the 
  

   rock 
  has 
  the 
  fine 
  texture 
  and 
  fissured 
  surface 
  usual 
  where 
  it 
  

   cooled 
  in 
  contact 
  with 
  the 
  sandstone. 
  Just 
  above 
  the 
  cave, 
  

  

  Inclined 
  columns 
  of 
  Pine 
  Rock, 
  above 
  the 
  '-Cave." 
  

  

  where 
  the 
  exterior 
  is 
  removed, 
  the 
  surface 
  is 
  made 
  up 
  of 
  the 
  

   ends 
  of 
  rude 
  columns. 
  A 
  profile 
  view 
  of 
  these 
  inclined 
  

   columns 
  from 
  a 
  point 
  just 
  south 
  is 
  shown 
  in 
  fig. 
  4.* 
  

  

  At 
  10, 
  (see 
  the 
  preceding 
  map) 
  the 
  north 
  wall 
  of 
  the 
  inclined 
  

   dike 
  is 
  uncovered 
  for 
  a 
  height 
  of 
  50 
  feet, 
  the 
  sandstone 
  having 
  

   been 
  carried 
  off 
  by 
  the 
  glacier. 
  \ 
  

  

  At 
  the 
  eastern 
  extremity 
  of 
  Fine 
  Pock 
  (near 
  C), 
  the 
  trap 
  

   of 
  the 
  north 
  wall 
  may 
  be 
  seen 
  in 
  contact 
  with 
  hard-baked' 
  

   sandstone. 
  In 
  the 
  large 
  quarry 
  just 
  south, 
  the 
  rock 
  exhibits 
  

   finely 
  the 
  transverse 
  lamination 
  crossing 
  the 
  dike 
  — 
  referred 
  to 
  

   on 
  page 
  82. 
  The 
  laminae 
  incline 
  10° 
  to 
  15° 
  to 
  the 
  eastward, 
  

   the 
  dip 
  being 
  80 
  to 
  85° 
  to 
  the 
  westward. 
  The 
  surfaces 
  of 
  the 
  

   plates 
  are 
  usually 
  yellowish-brown 
  with 
  limonite 
  for 
  scores 
  of 
  

   feet 
  from 
  the 
  summit, 
  owing 
  to 
  the 
  waters 
  that 
  penetrate 
  from 
  

   the 
  surface 
  downward 
  and 
  oxydize 
  the 
  iron 
  of 
  the 
  rock 
  ; 
  but 
  

   in 
  the 
  transverse 
  joints 
  or 
  cracks, 
  which 
  are 
  less 
  accessible 
  to 
  

   the 
  waters, 
  there 
  is 
  usually 
  a 
  coating 
  of 
  stilbite 
  and 
  sometimes 
  

  

  * 
  From 
  a 
  photograph 
  by 
  G-. 
  X. 
  Lawson, 
  of 
  the 
  class 
  at 
  Tale 
  of 
  1890 
  ; 
  taken 
  in 
  

   December. 
  1890. 
  

  

  f 
  The 
  shaping- 
  of 
  the 
  northern 
  slopes 
  of 
  the 
  Pine 
  Rock 
  ridge 
  is 
  a 
  part 
  of 
  the 
  

   same 
  work 
  of 
  the 
  ice 
  ; 
  and 
  the 
  trend 
  of 
  the 
  mass, 
  like 
  that 
  of 
  Sachem's 
  "Ridge, 
  

   (Plate 
  II), 
  indicates 
  the 
  direction 
  of 
  movement 
  of 
  the 
  glacier. 
  The 
  same 
  is 
  true 
  

   for 
  the 
  northern 
  slopes 
  of 
  Whitney 
  Peak 
  and 
  Indian 
  Head. 
  

  

  