﻿86 
  J. 
  D. 
  Dana 
  — 
  Features 
  of 
  non-volcanic 
  Igneous 
  Ejections. 
  

  

  of 
  other 
  zeolites, 
  as 
  chabazite, 
  analcite, 
  heulandite.* 
  The 
  

   dike 
  has 
  a 
  few 
  transverse 
  courses 
  of 
  fracture 
  containing 
  prehnite 
  

   and 
  occasionally 
  apophyllite, 
  but 
  no 
  longitudinal 
  have 
  been 
  

   observed. 
  

  

  A 
  sandstone 
  ridge 
  connects 
  A 
  and 
  BB', 
  in 
  which 
  the 
  rock 
  is 
  

   hard, 
  and 
  has 
  the 
  strike 
  N. 
  40 
  o 
  -45° 
  E., 
  and 
  the 
  dip 
  45° 
  S., 
  

   becoming 
  K 
  30° 
  E. 
  and 
  30° 
  to 
  35° 
  in 
  dip 
  more 
  to 
  the 
  west. 
  

   It 
  is 
  mostly 
  a 
  coarse 
  sandstone 
  ; 
  but 
  some 
  layers 
  contain 
  stones 
  

   4 
  to 
  5 
  inches 
  in 
  diameter. 
  

  

  Origin 
  of 
  the 
  Features 
  of 
  the 
  Mock. 
  

  

  The 
  existence 
  of 
  so 
  many 
  outlets 
  of 
  trap 
  in 
  the 
  small 
  space, 
  

   and 
  the 
  irregular 
  forms 
  of 
  the 
  areas 
  are 
  unusual 
  facts. 
  BB' 
  is 
  

   short, 
  broad 
  and 
  blunt, 
  shield-shaped 
  ; 
  and 
  CC, 
  is 
  duck-like 
  in 
  

   shape, 
  the 
  irregular 
  bosses 
  at 
  the 
  northwest 
  end 
  (EE') 
  making 
  

   the 
  neck 
  and 
  head. 
  These 
  bosses 
  are 
  not 
  in 
  the 
  line 
  of 
  the 
  

   dike, 
  and 
  must 
  be 
  due 
  to 
  a 
  local 
  catastrophe. 
  In 
  view 
  of 
  the 
  

   great 
  inclination 
  of 
  the 
  fissure, 
  and 
  its 
  depth 
  of 
  2000 
  to 
  3000 
  

   feet 
  in 
  the 
  weak 
  sandstone, 
  a 
  caving 
  in 
  of 
  some 
  part 
  of 
  its 
  

   northern 
  or 
  hanging 
  wall 
  would 
  be 
  of 
  extreme 
  probability. 
  

   Such 
  a 
  catastrophe 
  would 
  account 
  for 
  the 
  stoppage 
  of 
  the 
  out- 
  

   flow 
  and 
  the 
  separation 
  thus 
  of 
  BB' 
  and 
  CC 
  ; 
  and 
  such 
  a 
  

   stoppage 
  of 
  the 
  up-thrust 
  lavas 
  would 
  explain 
  their 
  escape 
  by 
  

   one 
  or 
  more 
  extemporized 
  outlets, 
  and 
  for 
  the 
  actual 
  position 
  

   of 
  the 
  apertures 
  on 
  the 
  north 
  side 
  of 
  the 
  fissure 
  ; 
  and 
  thereby 
  

   for 
  the 
  making 
  of 
  the 
  bosses^ 
  The 
  obstructed 
  lavas 
  of 
  the 
  

   fissure 
  may 
  also 
  have 
  found 
  exit 
  in 
  the 
  western 
  dike, 
  A. 
  

  

  The 
  trap-mass 
  D 
  is 
  possibly 
  a 
  result 
  of 
  a 
  second 
  smaller 
  

   catastrophe 
  of 
  like 
  character 
  ; 
  but 
  its 
  separation 
  from 
  CC', 
  may 
  

   be 
  a 
  result 
  of 
  erosion. 
  

  

  Another 
  consequence 
  of 
  the 
  great 
  inclination 
  of 
  the 
  fissure 
  is 
  

   the 
  exposure 
  of 
  the 
  dike 
  of 
  heavy 
  trap 
  to 
  degradation 
  through 
  

   the 
  removal 
  of 
  the 
  supporting 
  sandstone 
  on 
  the 
  south 
  side. 
  

   Such 
  undermining 
  has 
  produced 
  the 
  steepness 
  of 
  the 
  southern 
  

   front. 
  And 
  sea-shore 
  waves 
  or 
  breakers 
  were 
  probably 
  the 
  

   chief 
  agent 
  — 
  the 
  shores 
  being 
  those 
  of 
  the 
  broad 
  center, 
  or 
  a 
  

   central 
  arm, 
  of 
  the 
  New 
  Haven 
  Bay. 
  

  

  2. 
  MILL 
  ROCK 
  AND 
  THE 
  WHITNEY 
  RIDGE. 
  

  

  Mill 
  Rock 
  is 
  one 
  mile 
  distant 
  from 
  the 
  east 
  end 
  of 
  Pine 
  

   Rock. 
  Its 
  length 
  to 
  Whitney 
  ville 
  or 
  Mill 
  River, 
  is 
  four-fifths 
  

   of 
  a 
  mile. 
  This 
  small 
  area, 
  as 
  is 
  seen 
  on 
  Plate 
  II, 
  and 
  better 
  in 
  

   the 
  following 
  larger 
  map, 
  has 
  four 
  independent 
  outlets 
  of 
  trap 
  — 
  

  

  * 
  The 
  surface 
  of 
  the 
  crust 
  of 
  zeolites 
  is 
  frequently 
  tinged 
  with 
  the 
  red 
  iron 
  

   oxide 
  — 
  which 
  is 
  a 
  probable 
  indication 
  of 
  heat 
  as 
  high 
  at 
  least 
  as 
  200° 
  F. 
  dur- 
  

   ing 
  the 
  formation 
  of 
  the 
  minerals. 
  

  

  