﻿J. 
  D. 
  Dana 
  — 
  Features 
  of 
  non-volcanic 
  Igneous 
  Ejections. 
  103 
  

  

  character, 
  excepting 
  that 
  the 
  apparent 
  dip 
  is 
  less. 
  They 
  may 
  

   be 
  followed 
  westward 
  along 
  the 
  quarry 
  man's 
  road 
  for 
  400 
  

   yards, 
  when 
  they 
  begin 
  to 
  pass 
  into 
  the 
  normal 
  sections 
  of 
  the 
  

   western 
  front, 
  that 
  is, 
  sections 
  in 
  which 
  the 
  lines 
  of 
  bedding 
  

   are 
  horizontal 
  because 
  they 
  are 
  in 
  the 
  line 
  of 
  strike 
  of 
  the 
  

   sandstone. 
  

  

  The 
  question 
  here 
  arises 
  : 
  Did 
  the 
  flowing 
  trap, 
  owing 
  to 
  its 
  

   movement 
  and 
  weight, 
  wear 
  off 
  the 
  layers 
  of 
  sandstone 
  and 
  so 
  

   make 
  the 
  succession 
  of 
  ledges 
  on 
  which 
  it 
  rests; 
  or 
  did 
  it 
  

   escape 
  from 
  its 
  confining 
  cover 
  of 
  sandstone 
  into 
  the 
  open 
  air 
  

   and 
  cover 
  in 
  its 
  flow 
  the 
  exposed 
  ledges 
  of 
  the 
  region. 
  The 
  

   former 
  is 
  probably 
  the 
  correct 
  view. 
  Had 
  the 
  flow 
  become 
  

   subaerial 
  there 
  would 
  have 
  been 
  at 
  once 
  a 
  decline 
  westward 
  in 
  

   the 
  level 
  of 
  its 
  upper 
  surface 
  ; 
  for 
  the 
  level 
  would 
  have 
  fallen 
  

   as 
  soon 
  as 
  the 
  resistance 
  from 
  confinement 
  ceased. 
  There 
  is 
  

   no 
  evidence 
  of 
  such 
  a 
  decline. 
  From 
  points 
  on 
  the 
  summit 
  

   close 
  to 
  the 
  western 
  precipice 
  the 
  surface 
  for 
  the 
  first 
  300 
  yards 
  

   has 
  generally 
  a 
  slope 
  eastward 
  of 
  1 
  to 
  4, 
  or 
  1 
  to 
  5, 
  correspond- 
  

   ing 
  to 
  a 
  pitch 
  "of 
  14° 
  to 
  11°. 
  The 
  decline 
  is 
  eastward 
  ; 
  not 
  

   westward. 
  Such 
  a 
  rise 
  westward, 
  even 
  if 
  only 
  5°, 
  would 
  be 
  an 
  

   impossibility 
  except 
  in 
  a 
  covered 
  passage-way, 
  that 
  is, 
  in 
  the 
  

   present 
  case, 
  one 
  having 
  a 
  cover 
  of 
  the 
  sandstone. 
  Other 
  

   evidence 
  bearing 
  in 
  the 
  same 
  direction 
  is 
  afforded 
  by 
  the 
  

   position 
  of 
  the 
  columns 
  along 
  the 
  western 
  front, 
  which 
  pitch 
  

   westward 
  15° 
  to 
  20°. 
  

  

  The 
  summit 
  slope 
  eastward 
  of 
  14° 
  to 
  11° 
  is 
  less 
  than 
  the 
  

   dip 
  of 
  the 
  sandstone, 
  and 
  favors 
  the 
  conclusion 
  that 
  the 
  

   underlying 
  sandstone 
  was 
  in 
  many 
  places 
  torn 
  up 
  by 
  th 
  • 
  

   heavily 
  moving 
  liquid 
  trap, 
  while 
  left 
  in 
  place 
  elsewhere. 
  

   The 
  floor 
  so 
  made 
  consisted 
  of 
  alternations 
  of 
  wide 
  strips 
  that 
  

   had 
  the 
  regular 
  dip 
  of 
  the 
  sandstone, 
  with 
  others 
  abraded 
  down 
  

   to 
  nearly 
  flat 
  and 
  ledgy 
  surfaces 
  ; 
  and 
  the 
  former 
  prevailed 
  

   sufficiently 
  to 
  determine 
  the 
  direction 
  of 
  the 
  contractional 
  

  

  