﻿84 
  J. 
  D. 
  Dana 
  — 
  Features 
  of 
  non-volcanic 
  Igneous 
  Ejections. 
  

  

  that 
  it 
  is 
  not 
  an 
  outlier 
  of 
  West 
  Rock, 
  but 
  part 
  of 
  the 
  Pine 
  

   Rock 
  group. 
  The 
  other 
  three 
  are, 
  more 
  evidently, 
  outlets 
  from 
  

   one 
  great 
  fissure. 
  The 
  width 
  of 
  the 
  larger 
  mass, 
  CC\ 
  is 
  about 
  

   300 
  feet 
  ; 
  and 
  it 
  is 
  therefore 
  one 
  of 
  the 
  widest 
  of 
  dikes. 
  The 
  

   dip 
  of 
  the 
  dike 
  is 
  50° 
  to 
  55° 
  northwestward. 
  This 
  inclined 
  

  

  Map 
  of 
  Pine 
  Rock. 
  

  

  Heights 
  reckoned 
  from 
  high-tide 
  level. 
  

   with 
  dotted 
  outline. 
  

  

  Areas 
  of 
  trap 
  

  

  position 
  (35° 
  to 
  40° 
  from 
  a 
  vertical) 
  is 
  given 
  the 
  dike 
  in 
  fig. 
  2, 
  in 
  

   which 
  DIKE 
  represents 
  a 
  section 
  of 
  it 
  between 
  its 
  sandstone 
  

   walls 
  before 
  denudation, 
  and 
  d 
  i 
  K 
  E, 
  the 
  same 
  through 
  the 
  

  

  highest 
  point 
  of 
  the 
  Rock 
  as 
  it 
  now 
  is— 
  or 
  was 
  before 
  recent 
  

   quarrying. 
  The 
  cross-lining 
  gives 
  the 
  direction 
  of 
  the 
  columnar 
  

   fractures. 
  The 
  other 
  figure, 
  fig. 
  3, 
  is 
  a 
  section 
  through 
  v 
  on 
  

   the 
  map, 
  where 
  the 
  removal 
  of 
  the 
  sandstone 
  of 
  the 
  southern 
  

   wall 
  (v, 
  in 
  the 
  section) 
  has 
  left 
  a 
  depression 
  called 
  the 
  Cave. 
  

   (The 
  sandstone 
  of 
  these 
  sections 
  is 
  now 
  concealed 
  by 
  the 
  debris, 
  

   and 
  outside 
  of 
  this 
  by 
  the 
  Terrace 
  formation.) 
  

  

  