﻿106 
  J. 
  D. 
  Dana 
  — 
  Features 
  of 
  non-volcanic 
  Igneous 
  Ejections. 
  

  

  tinguished. 
  The 
  deeper 
  and 
  more 
  abrupt 
  notches 
  we 
  should 
  

   be 
  disposed 
  to 
  refer 
  to 
  the 
  former 
  cause. 
  

  

  As 
  the 
  Bache 
  map 
  of 
  West 
  Kock 
  ridge 
  indicates 
  by 
  its 
  con- 
  

   tour 
  lines, 
  within 
  a 
  mile 
  and 
  a 
  quarter 
  of 
  the 
  south 
  end 
  of 
  West 
  

   Kock, 
  there 
  are 
  three 
  gaps. 
  Two 
  are 
  included 
  on 
  Plate 
  II. 
  

   At 
  the 
  first, 
  the 
  height 
  of 
  the 
  ridge 
  falls 
  off 
  sixty 
  feet 
  

   in 
  the 
  course 
  of 
  500 
  yards. 
  The 
  second, 
  situated 
  300 
  yards 
  

   farther 
  north, 
  and 
  called 
  the 
  "Judges' 
  Notch" 
  because 
  near 
  

   the 
  "Judges' 
  Cave," 
  is 
  similar 
  to 
  the 
  first 
  in 
  depth, 
  but 
  

   narrows 
  more 
  down 
  the 
  western 
  front. 
  Half 
  a 
  mile 
  farther 
  

  

  north 
  is 
  the 
  third, 
  called 
  the 
  

   " 
  Wintergreen 
  Notch." 
  It 
  

   is 
  one 
  of 
  the 
  larger 
  gaps 
  in 
  

   the 
  ridge. 
  Along 
  the 
  sum- 
  

   mit, 
  both 
  from 
  the 
  north 
  

   and 
  the 
  south, 
  there 
  is 
  a 
  

   descent 
  of 
  100 
  feet, 
  from 
  a 
  

   height 
  of 
  440 
  feet 
  to 
  340. 
  

   Figure 
  16, 
  from 
  the 
  Bache 
  

   map, 
  exhibits 
  the 
  facts.* 
  

   The 
  decline 
  is 
  gradual 
  on 
  

   the 
  south 
  side, 
  but 
  very 
  

   rapid 
  northward 
  ; 
  in 
  the 
  

   latter 
  direction 
  the 
  level 
  of 
  

   460 
  feet 
  is 
  reached 
  at 
  the 
  

   same 
  distance 
  from 
  the 
  cen- 
  

   ter 
  of 
  the 
  gap 
  as 
  440 
  on 
  the 
  

   south. 
  This 
  third 
  gap 
  is 
  

   probably 
  one 
  of 
  those 
  caused 
  by 
  obstructions 
  to 
  the 
  outflow, 
  

   whatever 
  the 
  fact 
  with 
  the 
  others. 
  The 
  stream, 
  in 
  con- 
  

   sequence 
  of 
  the 
  obstruction, 
  reached 
  a 
  height 
  at 
  the 
  gap 
  

   of 
  but 
  340 
  feet 
  ; 
  but 
  just 
  beyond, 
  the 
  lavas 
  that 
  had 
  

   been 
  held 
  back, 
  made 
  the 
  abrupt 
  rise 
  in 
  the 
  ridge 
  to 
  440 
  

   and 
  460 
  feet. 
  The 
  correctness 
  of 
  this 
  explanation 
  appears 
  

   to 
  be 
  sustained 
  also 
  by 
  the 
  abruptness 
  of 
  the 
  rise 
  in 
  the 
  

   slopes 
  east 
  of 
  the 
  gap, 
  as 
  the 
  contour 
  lines 
  in 
  the 
  figure 
  

   show, 
  and 
  the 
  great 
  breadth 
  of 
  the 
  nearly 
  horizontal 
  area 
  

   farther 
  east. 
  It 
  will 
  be 
  observed 
  also 
  that 
  the 
  summit 
  

   of 
  the 
  ridge 
  north 
  of 
  the 
  gap 
  is 
  farther 
  to 
  the 
  west 
  than 
  

   that 
  on 
  the 
  south. 
  (Arrows 
  are 
  inserted 
  to 
  make 
  this 
  dis- 
  

   tinct.) 
  It 
  is 
  so 
  because 
  any 
  given 
  amount 
  of 
  trap 
  depends 
  for 
  

   its 
  height 
  on 
  the 
  distance 
  it 
  flowed 
  westward 
  up 
  the 
  inclined 
  

   sandstone 
  layers. 
  It 
  may 
  be 
  observed 
  that 
  not 
  only 
  the 
  height, 
  

  

  * 
  The 
  west 
  side 
  of 
  the 
  ridge 
  in 
  this 
  part, 
  as 
  elsewhere, 
  is 
  the 
  precipitous 
  side. 
  

   bold 
  columnar 
  above. 
  Its 
  upper 
  200 
  to 
  225 
  feet 
  usually 
  consist 
  of 
  trap, 
  and 
  ihe 
  

   part 
  below 
  of 
  sandstone 
  ; 
  but 
  the 
  junction-plane 
  at 
  the 
  Notch 
  is 
  concealed 
  by 
  

   trap 
  debris, 
  so 
  that 
  its 
  actual 
  height 
  is 
  not 
  determinable. 
  

  

  Wintergreen 
  Notch. 
  

  

  