﻿the 
  P 
  ennsylvanian 
  Strata 
  of 
  Kansas. 
  369 
  

  

  Characteristics 
  and 
  Lithology 
  of 
  the 
  Bowlders. 
  

  

  Many 
  of 
  the 
  bowlders 
  are 
  almost 
  completely 
  decayed 
  and 
  are 
  

   so 
  soft 
  that 
  they 
  can 
  be 
  dug 
  through 
  with 
  a 
  spade, 
  Mr. 
  E. 
  M. 
  

   Stryker 
  having 
  thus 
  dng 
  about 
  fifteen 
  inches 
  into 
  one 
  which 
  

   was 
  buried 
  in 
  the 
  ground. 
  The 
  most 
  badly 
  decayed 
  ones 
  are 
  

   in 
  the 
  ground 
  ; 
  but, 
  as 
  shown 
  by 
  fragments, 
  there 
  were 
  others 
  in 
  

   the 
  midst 
  of 
  the 
  solid 
  bowlders 
  now 
  on 
  the 
  surface 
  which 
  fell 
  

   to 
  pieces 
  as 
  fast 
  as 
  they 
  became 
  exposed. 
  Some 
  of 
  those 
  on 
  the 
  

   surface 
  have 
  the 
  constituent 
  minerals 
  so 
  poorly 
  held 
  together 
  

   that 
  they 
  can 
  be 
  crumbled 
  with 
  the 
  hands. 
  Others 
  which 
  are 
  

   still 
  compact 
  have 
  deep 
  corrosion 
  pits 
  which 
  reach 
  into 
  the 
  

   stone 
  for 
  six 
  or 
  more 
  inches. 
  It 
  appears 
  quite 
  probable 
  that 
  

   the 
  greater 
  number 
  of 
  the 
  smaller 
  bowlders 
  have 
  been 
  pro- 
  

   duced 
  by 
  the 
  breaking 
  up 
  since 
  deposition 
  of 
  the 
  larger, 
  for 
  

   in 
  many 
  instances 
  the 
  former 
  have 
  the 
  minerals 
  poorly 
  held 
  

   together 
  and 
  are 
  of 
  angular 
  and 
  irregular 
  outlines. 
  They 
  have 
  

   the 
  appearance 
  of 
  having 
  been 
  separated 
  from 
  larger 
  pieces 
  

   and 
  where 
  the 
  bowlders 
  are 
  numerous 
  there 
  are 
  not 
  a 
  great 
  

   many 
  small 
  ones 
  except 
  in 
  those 
  places 
  where 
  a 
  large 
  one 
  is 
  

   crumbling 
  to 
  pieces. 
  It 
  is 
  plainly 
  evident 
  that 
  the 
  granite 
  

   bowlders 
  are 
  very 
  old 
  and 
  have 
  been 
  where 
  they 
  now 
  occur 
  a 
  

   very 
  long 
  time. 
  

  

  The 
  minerals 
  composing 
  the 
  rock 
  of 
  the 
  Rose 
  bowlders 
  are 
  

   glassy 
  white 
  and 
  pale 
  bluish-white 
  quartz 
  and 
  gray 
  orthoclase 
  

   and 
  oligoclase 
  feldspar, 
  considerable 
  proportions 
  of 
  the 
  latter 
  

   being 
  present 
  as 
  phenocrysts, 
  of 
  which 
  some 
  are 
  fully 
  three- 
  

   fourths 
  of 
  an 
  inch 
  across 
  in 
  their 
  greatest 
  dimension. 
  Quartz 
  

   is 
  also 
  present 
  as 
  phenocrysts 
  of 
  which 
  the 
  largest 
  are 
  about 
  

   half 
  an 
  inch 
  across. 
  Compared 
  to 
  the 
  quartz, 
  the 
  feldspars 
  

   predominate 
  in 
  a 
  proportion 
  estimated 
  at 
  about 
  two 
  to 
  one. 
  A 
  

   few 
  grains 
  of 
  magnetite 
  are 
  present 
  together 
  with 
  a 
  few 
  grains 
  

   of 
  some 
  ferro-magnesian 
  mineral 
  which 
  has 
  been 
  chloritized 
  so 
  

   as 
  to 
  be 
  unrecognizable. 
  Originally 
  it 
  was 
  probably 
  either 
  

   hornblende 
  or 
  biotite. 
  Professor 
  Joseph 
  Barrell, 
  to 
  whom 
  some 
  

   of 
  the 
  specimens 
  were 
  submitted 
  for 
  examination, 
  confirmed 
  

   the 
  identifications 
  and 
  stated 
  that 
  " 
  the 
  rock 
  has 
  been 
  shat- 
  

   tered, 
  but 
  the 
  fragments 
  are 
  still 
  largely 
  in 
  their 
  original 
  juxta- 
  

   position. 
  In 
  connection 
  with 
  this 
  shattering 
  there 
  was 
  a 
  rece- 
  

   mentation 
  with 
  fine-grained 
  quartz 
  and 
  feldspar 
  showing 
  a 
  

   trace 
  of 
  poikilitic 
  tendency."* 
  The 
  shattering 
  of 
  the 
  rock 
  is 
  

   not 
  apparent 
  on 
  all 
  of 
  the 
  granite 
  bowlders 
  although 
  it 
  

   is 
  plain 
  from 
  every 
  one 
  that 
  they 
  are 
  closely 
  related 
  and 
  w 
  r 
  ere 
  

   evidently 
  derived 
  from 
  the 
  same 
  mass 
  of 
  rock. 
  The 
  intimate 
  

   dovetailing 
  of 
  the 
  minerals 
  absolutely 
  puts 
  out 
  of 
  consideration 
  

   any 
  possibility 
  that 
  the 
  rock 
  is 
  an 
  arkose 
  or 
  a 
  breccia. 
  

  

  * 
  Personal 
  communication, 
  August 
  17, 
  1916. 
  

  

  