﻿E. 
  H. 
  Perkins 
  — 
  Dighton 
  Conglomerate. 
  73 
  

  

  C. 
  Larger 
  fragments. 
  

  

  1. 
  Large 
  and 
  small 
  fragments 
  mixed, 
  unsorted. 
  

  

  2. 
  Pebbles 
  and 
  cobbles 
  more 
  angular 
  than 
  those 
  of 
  

  

  a 
  normal 
  marine 
  conglomerate. 
  

  

  D. 
  Associated 
  beds. 
  

  

  1. 
  The 
  series 
  from 
  arkose 
  through 
  sandstones 
  and 
  

  

  shales 
  to 
  conglomerate 
  is 
  typical 
  of 
  continental 
  

   rather 
  than 
  marine 
  origin. 
  

  

  2. 
  Large 
  amounts 
  of 
  coal 
  and 
  coaly 
  shale. 
  

  

  3. 
  Contemporaneous 
  erosion. 
  

  

  4. 
  Irregular 
  cross-bedding. 
  

  

  5. 
  Rain-prints 
  and 
  mud-cracks. 
  

  

  E. 
  Fossils. 
  

  

  1. 
  Absence 
  of 
  remains 
  of 
  animal 
  life. 
  

  

  2. 
  Abundance 
  of 
  plant 
  fossils. 
  

   II. 
  Evidence 
  of 
  ice 
  action. 
  

  

  A. 
  Directly 
  as 
  glaciers 
  in 
  zone 
  of 
  deposition 
  forming 
  tillites. 
  

  

  No 
  evidence. 
  

  

  B. 
  Indirectly 
  at 
  headwaters 
  of 
  streams 
  forming 
  aqueogla- 
  

  

  cial 
  deposits. 
  

  

  1. 
  Large 
  percentages 
  of 
  beveled 
  surfaces 
  on 
  pebbles. 
  

  

  2. 
  Rhombic 
  and 
  blunted 
  and 
  pointed 
  pebbles 
  common. 
  

  

  3. 
  Concave 
  fractures 
  common. 
  

  

  4. 
  Rafted 
  bowlders 
  in 
  associated 
  deposits. 
  

  

  5. 
  The 
  great 
  number 
  of 
  large 
  bowlders 
  in 
  the 
  New- 
  

  

  port 
  area 
  seem 
  to 
  require 
  either 
  the 
  wedge 
  work 
  

   of 
  ice 
  or 
  the 
  plucking 
  power 
  of 
  a 
  glacier 
  for 
  

   their 
  production. 
  

  

  III. 
  Evidences 
  for 
  a 
  cool 
  climate. 
  

  

  1. 
  See 
  evidences 
  for 
  ice 
  action 
  above. 
  

  

  2. 
  Freshness 
  of 
  material. 
  

  

  3. 
  Abundance 
  of 
  feldspar 
  in 
  matrix. 
  

  

  4. 
  Preservation 
  of 
  plant 
  fossils 
  from 
  decay. 
  

  

  5. 
  Blue-gray 
  color 
  indication 
  of 
  absence 
  of 
  dehydra- 
  

  

  tion 
  of 
  iron 
  by 
  heat. 
  

  

  IV. 
  Evidence 
  for 
  a 
  moist 
  climate. 
  

  

  1. 
  See 
  evidence 
  for 
  stream 
  and 
  ice 
  action 
  above. 
  

  

  2. 
  Abundance 
  of 
  plant 
  life. 
  

  

  3. 
  Lack 
  of 
  dehydration 
  of 
  iron. 
  

  

  Conclusions. 
  

  

  1. 
  The 
  Dighton 
  conglomerate 
  is 
  believed 
  to 
  be 
  a 
  

   fluviatile 
  deposit. 
  

  

  2. 
  The 
  great 
  size 
  of 
  the 
  fragments 
  indicates 
  a 
  rapid 
  

   and 
  vigorous 
  erosion 
  at 
  no 
  great 
  distance 
  from 
  the 
  site 
  

   of 
  deposition. 
  The 
  deposit 
  is 
  therefore 
  believed 
  to 
  have 
  

   been 
  formed 
  at 
  the 
  base 
  of 
  a 
  mountain 
  range. 
  

  

  3. 
  As 
  the 
  coarser 
  material 
  is 
  in 
  the 
  eastern 
  and 
  south- 
  

   eastern 
  part 
  of 
  the 
  basin, 
  the 
  range 
  is 
  believed 
  to 
  have 
  

  

  