﻿380 
  W. 
  H. 
  Twenhofel 
  — 
  Granite 
  Bowlders. 
  

  

  age,* 
  extended 
  the 
  probability 
  of 
  cool 
  climates 
  for 
  this 
  con- 
  

   tinent 
  to 
  the 
  early 
  Pennsylvania!!. 
  It 
  is 
  not 
  possible 
  to 
  corre- 
  

   late 
  the 
  Rose 
  bowlders 
  with 
  those 
  in 
  the 
  Caney 
  shale, 
  but 
  it 
  is 
  

   possible 
  that 
  they 
  may 
  be 
  correlated 
  with 
  the 
  Squantum 
  tillite 
  

   near 
  Boston. 
  f 
  This 
  is 
  a 
  part 
  of 
  the 
  Roxbury 
  conglomerate 
  

   and 
  supposedly 
  of 
  Permian 
  age, 
  although 
  the 
  age 
  determination 
  

   is 
  based 
  merely 
  on 
  the 
  resemblance 
  that 
  this 
  conglomerate 
  

   bears 
  to 
  Permo-Carboniferous 
  conglomerates 
  of 
  the 
  Narragan- 
  

   sett 
  and 
  Norfolk 
  basins, 
  an 
  extremely 
  hazardous 
  feature 
  on 
  

   which 
  to 
  base 
  a 
  correlation. 
  If 
  the 
  correlation 
  of 
  the 
  Rose 
  

   bowlders 
  with 
  the 
  Squantum 
  tillite 
  can 
  be 
  made, 
  the 
  position 
  

   of 
  the 
  former, 
  if 
  they 
  are 
  situated 
  where 
  this 
  article 
  assumes, 
  

   definitely 
  fixes 
  the 
  age 
  of 
  both 
  and 
  also 
  the 
  time 
  relations 
  of 
  the 
  

   beginning 
  of 
  the 
  Permo-Carboniferous 
  cold 
  climates 
  so 
  far 
  as 
  

   the 
  North 
  American 
  continent 
  is 
  concerned. 
  The 
  LeRoy 
  shales 
  

   have 
  been 
  correlated 
  in 
  a 
  general 
  way 
  by 
  SchuchertJ 
  with 
  

   the 
  Conemaugh 
  of 
  Pennsylvania. 
  The 
  cold 
  conditions 
  of 
  the 
  

   late 
  Paleozoic 
  have 
  usually 
  been 
  assumed 
  to 
  have 
  occurred 
  dur- 
  

   ing 
  the 
  Permian 
  which 
  for 
  the 
  Kansas 
  section 
  is 
  generally 
  not 
  

   considered 
  to 
  have 
  begun 
  until 
  the 
  close 
  of 
  Wabaunsee 
  deposi- 
  

   tion, 
  which 
  is 
  separated 
  from 
  what 
  is 
  considered 
  the 
  probable 
  

   stratigraphic 
  position 
  of 
  the 
  bowlders 
  by 
  between 
  thirteen 
  and 
  

   fourteen 
  feet 
  of 
  sediments. 
  § 
  Some 
  writers 
  have 
  begun 
  the 
  

   Permian 
  at 
  a 
  slightly 
  lower 
  position, 
  but 
  no 
  one 
  has 
  attempted 
  

   to 
  include 
  the 
  Douglas 
  formation 
  of 
  which 
  the 
  LeRoy 
  member 
  

   is 
  a 
  part, 
  since 
  the 
  faunas 
  of 
  that 
  and 
  the 
  two 
  overlying 
  forma- 
  

   tions 
  are 
  typically 
  upper 
  Pennsylvanian. 
  It 
  follows, 
  therefore, 
  

   if 
  the 
  assumptions 
  which 
  have 
  been 
  made 
  respecting 
  the 
  strati- 
  

   graphic 
  position 
  of 
  the 
  bowlders 
  be 
  correct, 
  that 
  glaciers 
  existed 
  

   over 
  the 
  higher 
  lands 
  during 
  parts 
  of 
  the 
  later 
  half 
  of 
  Penn- 
  

   sylvanian 
  time. 
  

  

  University 
  of 
  Wisconsin, 
  

   Madison, 
  Wis. 
  

  

  * 
  Ulrich, 
  Bull. 
  Geol. 
  Soc. 
  Am., 
  vol. 
  xxii, 
  pi. 
  29. 
  

  

  f 
  Sayles, 
  Bull. 
  Mus. 
  Comp. 
  Zool., 
  vol. 
  lvi, 
  No. 
  2, 
  Geol. 
  Ser., 
  vol. 
  x, 
  pp. 
  141- 
  

   175, 
  1914. 
  

  

  \ 
  Schuchert, 
  Bull. 
  Geol. 
  Soc, 
  Am., 
  vol. 
  xx, 
  p. 
  558, 
  1909. 
  

   §Haworth, 
  Kan. 
  Univ. 
  Geol. 
  Surv., 
  vol. 
  ix, 
  pi. 
  Ill, 
  1908. 
  

  

  / 
  

  

  