﻿66 
  E. 
  H. 
  Perkins 
  — 
  Bight 
  on 
  Conglomerate, 
  

  

  scattered 
  a 
  little 
  distance 
  apart. 
  Gregory 
  4 
  mentions 
  

   these 
  pebble 
  bands 
  as 
  a 
  common 
  feature 
  of 
  stream 
  action 
  

   in 
  the 
  arid 
  regions 
  of 
  the 
  sonthwest. 
  The 
  writer 
  has 
  also 
  

   found 
  them 
  on 
  several 
  occasions 
  in 
  Pleistocene 
  ontwash 
  

   plains. 
  

  

  The 
  scattering 
  of 
  isolated 
  pebbles 
  through 
  sands 
  and 
  

   shales 
  is 
  a 
  common 
  feature 
  of 
  river 
  work. 
  Gregory 
  5 
  

   mentions 
  it 
  as 
  common 
  in 
  the 
  stream 
  deposits 
  of 
  the 
  

   southwest. 
  The 
  author 
  has 
  found 
  these 
  scattered 
  peb- 
  

   bles 
  in 
  glacial 
  outwash 
  dep-osits, 
  in 
  the 
  Columbian 
  

   deposits 
  around 
  Washington 
  and 
  in 
  the 
  shale 
  beds 
  con- 
  

   nected 
  with 
  the 
  Squantum 
  tillite. 
  In 
  the 
  Dighton 
  forma- 
  

   tion 
  the 
  sandstones 
  that 
  are 
  interbedded 
  with 
  the 
  

   conglomerate 
  contain 
  isolated 
  pebbles 
  in 
  about 
  one-third 
  

   of 
  the 
  outcrops 
  noted. 
  

  

  Isolated 
  bowlders 
  and 
  cobbles 
  may 
  occur 
  in 
  similar 
  

   situations 
  to 
  those 
  in 
  which 
  the 
  isolated 
  pebbles 
  are 
  

   found. 
  These 
  larger 
  fragments 
  are 
  transported 
  by 
  tree 
  

   or 
  ice 
  rafts. 
  Such 
  rafted 
  bowlders 
  are 
  found 
  in 
  Pleisto- 
  

   cene 
  outwash 
  deposits, 
  and 
  also 
  occur 
  in 
  the 
  shales 
  asso- 
  

   ciated 
  with 
  the 
  Squantum 
  tillite. 
  The 
  only 
  case 
  of 
  

   undoubted 
  rafting 
  in 
  the 
  Narragansett 
  Basin 
  was 
  found 
  

   at 
  Rocky 
  Point, 
  where 
  a 
  granite 
  cobble 
  and 
  a 
  quartzite 
  

   bowlder 
  lie 
  isolated 
  in 
  a 
  fine-grained 
  sandstone. 
  The 
  

   beds 
  are 
  well 
  up 
  in 
  the 
  Rhode 
  Island 
  formation. 
  

  

  In 
  addition 
  to 
  pebble 
  bands 
  and 
  isolated 
  pebbles, 
  the 
  

   sandstone 
  layers 
  of 
  the 
  Dighton 
  formation 
  contain 
  nests 
  

   of 
  pebbles. 
  These 
  consist 
  of 
  a 
  little 
  bunch 
  of 
  pebbles 
  in 
  

   the 
  finer 
  rocks. 
  These 
  nests 
  of 
  pebbles 
  might 
  be 
  ex- 
  

   plained 
  in 
  two 
  ways 
  : 
  an 
  ice 
  cake 
  might 
  strand 
  on 
  a 
  

   river 
  bar 
  and 
  on 
  melting 
  deposit 
  the 
  pebbles 
  it 
  carried 
  

   in 
  a 
  limited 
  area, 
  or 
  a 
  pebble 
  lodged 
  on 
  the 
  stream 
  bed 
  

   might 
  catch 
  and 
  hold 
  other 
  pebbles 
  either 
  by 
  contact 
  or 
  

   by 
  lessening 
  the 
  velocity 
  of 
  the 
  water 
  in 
  its 
  vicinity. 
  

  

  The 
  thickness 
  of 
  the 
  Dighton 
  conglomerate 
  is 
  esti- 
  

   mated 
  by 
  Woodward 
  to 
  be 
  from 
  1000 
  to 
  1500 
  feet. 
  The 
  

   outcrops 
  extend 
  from 
  Newport 
  40 
  miles 
  north 
  to 
  Attle- 
  

   boro, 
  while 
  the 
  synclines 
  extend 
  12 
  or 
  15 
  miles 
  in 
  an 
  east 
  

   and 
  west 
  line. 
  This 
  indicates 
  a 
  mass 
  of 
  material 
  far 
  in 
  

   excess 
  of 
  the 
  amount 
  of 
  material 
  in 
  the 
  usual 
  marine 
  

   conglomerate. 
  To 
  quote 
  Gregory: 
  6 
  "As 
  preserved 
  in 
  

  

  4 
  Gregory, 
  H. 
  E., 
  The 
  Formation 
  and 
  Distribution 
  of 
  Fluviatile 
  and 
  

   Marine 
  Gravels, 
  this 
  Journal 
  (4), 
  39, 
  487-508, 
  1915. 
  

   3 
  Gregory, 
  H. 
  E., 
  op. 
  cit. 
  

   6 
  Gregory, 
  H. 
  E., 
  op. 
  cit. 
  

  

  