﻿276 
  E. 
  B. 
  Branson 
  — 
  Geologic 
  Section 
  in 
  Missouri. 
  

  

  Younger 
  Deposits. 
  — 
  East 
  of 
  the 
  Missouri 
  Eiver 
  along 
  

   the 
  section 
  glacial 
  drift 
  occurs, 
  undisturbed 
  here 
  and 
  

   there 
  in 
  protected 
  places, 
  but 
  much 
  more 
  commonly 
  gla- 
  

   cial 
  materials 
  are 
  mingled 
  with 
  residual 
  and 
  wind-blown 
  

   materials 
  to 
  make 
  up 
  the 
  mantle 
  rock. 
  Loess 
  caps 
  most 
  

   of 
  the 
  hills 
  near 
  the 
  Missouri 
  Eiver 
  and 
  laps 
  down 
  over 
  

   the 
  sidehills 
  in 
  many 
  places 
  to- 
  meet 
  the 
  alluvium 
  of 
  the 
  

   valleys. 
  The 
  loess 
  reaches 
  a 
  thickness 
  of 
  50 
  feet 
  or 
  

   more 
  but 
  is 
  ordinarily 
  less 
  than 
  20 
  feet 
  in 
  thickness. 
  On 
  

   the 
  hilltops 
  a 
  few 
  miles 
  from 
  the 
  river 
  finer, 
  wind-blown 
  

   materials 
  make 
  up 
  most 
  of 
  the 
  mantle 
  rock 
  and 
  under 
  it 
  

   are 
  residual 
  and 
  glacial 
  materials. 
  Most 
  of 
  the 
  residual 
  

   deposits 
  are 
  composed 
  of 
  chert 
  derived 
  from 
  the 
  cherty 
  

   limestones 
  and 
  dolomites. 
  

  

  Keyes 
  Sections. 
  1 
  — 
  Dr. 
  Charles 
  Keyes 
  recently 
  pub- 
  

   lished 
  sections 
  that 
  differ 
  so 
  widely 
  from 
  the 
  writer's 
  

   observations 
  that 
  it 
  seems 
  worthwhile 
  pointing 
  out 
  the 
  

   differences. 
  

  

  Keyes' 
  sections 
  show 
  the 
  Chouteau 
  resting 
  on 
  the 
  

   Hannibal 
  shales, 
  which, 
  he 
  says, 
  "decline 
  in 
  thickness 
  

   westward 
  until 
  by 
  the 
  time 
  Cooper 
  County 
  is 
  reached 
  

   they 
  disappear 
  by 
  attenuation. 
  ' 
  ' 
  The 
  writer 
  does 
  not 
  

   know 
  of 
  a 
  place 
  where 
  the 
  Chouteau 
  rests 
  on 
  the 
  Hanni- 
  

   bal 
  excepting 
  within 
  about 
  20 
  miles 
  of 
  Hannibal. 
  At 
  the 
  

   western 
  end 
  of 
  his 
  section 
  Keyes 
  shows 
  the 
  Chouteau 
  

   resting 
  on 
  the 
  Louisiana 
  limestone 
  but 
  the 
  Louisiana 
  

   does 
  not 
  outcrop 
  within 
  100 
  miles 
  of 
  this 
  western 
  end 
  

   and 
  probably 
  does 
  not 
  occur 
  within 
  90 
  miles 
  of 
  it. 
  

   Keyes' 
  section 
  shows 
  the 
  Saverton 
  shales 
  extending 
  

   nearly 
  to 
  the 
  western 
  end, 
  but 
  these 
  shales 
  are 
  not 
  known 
  

   within 
  100 
  miles 
  of 
  that 
  place. 
  His 
  section 
  shows 
  the 
  

   Snider 
  shales 
  extending 
  from 
  Hannibal 
  to 
  Cooper 
  

   County. 
  The 
  writer 
  has 
  mapped 
  these 
  shales 
  in 
  what 
  

   appears 
  to 
  be 
  their 
  total 
  extent, 
  and 
  that 
  is 
  entirely 
  in 
  

   Callaway 
  and 
  Montgomery 
  counties. 
  The 
  Callaway 
  

   limestone 
  appears 
  in 
  Keyes' 
  section 
  from 
  its 
  western 
  

   end 
  to 
  near 
  Hannibal; 
  some 
  30 
  miles 
  too 
  far 
  west 
  and 
  

   at 
  least 
  that 
  distance 
  too 
  far 
  northeast. 
  

  

  Keyes 
  \ 
  section 
  shows 
  Silurian 
  all 
  the 
  way 
  from 
  Sedalia 
  

   to 
  Hannibal. 
  The 
  writer 
  has 
  not 
  found 
  Silurian 
  out- 
  

   cropping 
  at 
  any 
  place 
  along 
  the 
  Missouri 
  River 
  or 
  its 
  

   tributaries. 
  It 
  probably 
  does 
  not 
  come 
  within 
  100 
  miles 
  

   of 
  Sedalia. 
  His 
  section 
  shows 
  no 
  Cooper 
  or 
  Sylamore, 
  

  

  7 
  Proceedings 
  of 
  the 
  Iowa 
  Academy 
  of 
  Sciences, 
  vol. 
  23, 
  p. 
  113. 
  

  

  