﻿the 
  Connecticut 
  Valley 
  Sandstone. 
  443 
  

  

  Again, 
  Dr. 
  Hovey 
  has 
  proved 
  that 
  the 
  first 
  trap-belt 
  east 
  of 
  

   the 
  Saltonstall 
  belt, 
  just 
  across 
  the 
  lake, 
  is 
  a 
  dike. 
  It 
  is 
  shown 
  

   by 
  the 
  hard-baked 
  condition 
  of 
  the 
  sandstone 
  on 
  its 
  east 
  side. 
  

   He 
  infers 
  also 
  that 
  it 
  was 
  subsequent 
  in 
  origin 
  to 
  the 
  Saltonstall 
  

   belt, 
  since 
  the 
  overlying 
  sandstone 
  contains 
  stones 
  of 
  vesicular 
  

   trap 
  which 
  were 
  derived 
  with 
  little 
  doubt, 
  like 
  those 
  of 
  the 
  Jura- 
  

   Trias 
  bowlder-conglomerate 
  south 
  of 
  the 
  northeastern 
  extrem- 
  

   ity, 
  from 
  this 
  northeastern 
  extremity. 
  The 
  position 
  of 
  the 
  hills 
  

   of 
  bowlder-conglomerate 
  is 
  shown 
  on 
  the 
  map 
  (Plate 
  XVI). 
  

  

  Further 
  the 
  bow- 
  shaped 
  form 
  of 
  Saltonstall 
  ridge 
  is 
  repeated 
  

   almost 
  exactly 
  in 
  the 
  larger 
  ridge 
  next 
  north, 
  the 
  Totoket, 
  and 
  

   hence 
  whatever 
  is 
  true 
  of 
  one 
  as 
  to 
  origin 
  is 
  pretty 
  certain 
  

   to 
  be 
  true 
  of 
  the 
  other. 
  And 
  what 
  then 
  of 
  the 
  other 
  ridges 
  

   farther 
  north 
  in 
  the 
  same 
  line 
  ? 
  

  

  We 
  note 
  also 
  that 
  these 
  bow-like 
  shapes, 
  in 
  the 
  trap, 
  with 
  

   the 
  dip 
  of 
  the 
  associated 
  sandstone 
  on 
  the 
  east 
  side 
  of 
  each 
  — 
  as 
  

   observed 
  by 
  Professor 
  Davis, 
  and 
  later 
  for 
  Saltonstall 
  ridge 
  by 
  

   Dr. 
  Hovey 
  — 
  toward 
  the 
  center 
  of 
  the 
  arc, 
  is 
  not 
  the 
  form 
  or 
  

   condition 
  to 
  be 
  looked 
  for 
  in 
  regions 
  of 
  monoclinal 
  uplifts. 
  

   The 
  dip 
  is 
  nearly 
  centroclinal 
  not 
  monoclinal. 
  

  

  The 
  map 
  enables 
  the 
  reader 
  to 
  observe 
  that 
  the 
  facts 
  here 
  

   cited 
  favoring 
  ejection 
  after 
  the 
  upturning, 
  that 
  is, 
  after 
  the 
  

   great 
  mountain-making 
  event 
  of 
  the 
  valley, 
  are 
  from 
  the 
  whole 
  

   width 
  of 
  the 
  southern 
  end 
  of 
  the 
  Jura-Trias 
  area 
  ; 
  and 
  it 
  is 
  

   also 
  seen 
  that 
  from 
  this 
  end 
  northward 
  there 
  are 
  suggestive 
  

   facts 
  bearing 
  in 
  the 
  same 
  direction. 
  Still 
  they 
  are 
  not 
  com- 
  

   plete 
  demonstration 
  that 
  this 
  is 
  true 
  for 
  the 
  northern 
  part 
  

   of 
  the 
  area. 
  We 
  have 
  to 
  leave 
  the 
  question 
  here 
  until 
  other 
  

   long 
  east-and-west 
  sections 
  of 
  north 
  and-south 
  trap 
  ridges 
  as 
  

   complete 
  as 
  that 
  of 
  West 
  Rock 
  have 
  been 
  reported 
  upon. 
  

  

  In 
  the 
  account 
  of 
  the 
  East 
  Pock 
  ridge 
  (page 
  98 
  of 
  this 
  

   volume) 
  the 
  separation 
  of 
  the 
  Snake 
  Pock 
  trap-mass 
  from 
  that 
  

   of 
  East 
  Pock 
  and 
  Indian 
  Head, 
  and 
  the 
  bow-like 
  shape 
  of 
  the 
  

   latter 
  with 
  centroclinal 
  dip 
  in 
  this 
  southeastern 
  part, 
  have 
  been 
  

   attributed 
  to 
  the 
  caving 
  in 
  of 
  the 
  hanging 
  wall 
  of 
  the 
  eastward- 
  

   dipping 
  fissure 
  that 
  supplied 
  the 
  lava. 
  It 
  is 
  worthy 
  of 
  consider- 
  

   ation 
  whether 
  the 
  south 
  end 
  of 
  the 
  Totoket 
  bow 
  and 
  the 
  north- 
  

   ern 
  of 
  the 
  Saltonstall 
  line 
  may 
  not 
  have 
  had 
  a 
  similar 
  origin. 
  

  

  Character 
  of 
  the 
  Mountain 
  uplifts 
  made 
  at 
  or 
  near 
  the 
  close 
  

   of 
  the 
  Jura-Trias 
  period. 
  

  

  Like 
  the 
  post-Carboniferous 
  mountain-uplifts, 
  the 
  parallel- 
  

   series 
  made 
  at 
  the 
  close 
  of 
  the 
  Jura-Trias 
  were 
  commenced 
  by 
  

   the 
  accumulation 
  of 
  sediments 
  in 
  gradually 
  deepening 
  depres- 
  

   sions 
  of 
  the 
  earth's 
  crust, 
  or 
  geosynclines 
  ; 
  but 
  while 
  the 
  era 
  of 
  

   deposition 
  in 
  the 
  former 
  ended 
  in 
  displacements 
  producing 
  great 
  

   flexures 
  of 
  the 
  accumulated 
  formations 
  besides 
  profound 
  faults, 
  

  

  