﻿W. 
  T. 
  Lee 
  — 
  Type 
  Section 
  of 
  Morrison 
  Formation. 
  183 
  

  

  Art. 
  XIII. 
  — 
  Type 
  Section 
  of 
  the 
  Morrison 
  Formation; 
  1 
  

   by 
  Willis 
  T. 
  Lee. 
  

  

  The 
  Morrison 
  formation 
  at 
  its 
  type 
  locality 
  at 
  Morri- 
  

   son, 
  Colorado, 
  requires 
  redefinition. 
  The 
  strata 
  origi- 
  

   nally 
  assigned 
  to 
  the 
  Morrison 
  include 
  some 
  that 
  are 
  

   equivalent 
  in 
  age 
  to 
  an 
  older 
  formation 
  ( 
  Sundance 
  of 
  the 
  

   Jurassic) 
  and 
  others 
  at 
  the 
  top 
  which 
  contain 
  fossil 
  

   plants 
  of 
  Upper 
  Cretaceous 
  type. 
  

  

  In 
  the 
  summer 
  of 
  1916, 
  I 
  visited 
  Morrison 
  in 
  company 
  

   with 
  Prof. 
  George 
  L. 
  Cannon, 
  who 
  assisted 
  years 
  ago 
  

   in 
  working 
  out 
  the 
  geology 
  of 
  this 
  region. 
  He 
  pointed 
  

   out 
  on 
  the 
  ground 
  the 
  formational 
  boundaries 
  used 
  by 
  

   him 
  and 
  his 
  associates 
  at 
  the 
  time 
  the 
  work 
  was 
  done 
  

   which 
  resulted 
  in 
  the 
  Denver 
  Monograph. 
  Together 
  we 
  

   went 
  to 
  the 
  old 
  quarries 
  where 
  the 
  dinosaurs 
  were 
  

   found. 
  At 
  this 
  time 
  he 
  called 
  my 
  attention 
  to 
  fossil 
  

   plants 
  in 
  the 
  upper 
  part 
  of 
  the 
  original 
  Morrison 
  and 
  

   also 
  to 
  the 
  plant 
  horizon 
  in 
  the 
  overlying 
  sandstone 
  

   where 
  he 
  and 
  Lieutenant 
  Beckwith 
  collected 
  the 
  plants 
  

   described 
  years 
  ago 
  by 
  Lesquereux 
  and 
  placed 
  in 
  the 
  

   Dakota 
  flora. 
  

  

  The 
  several 
  lithologic 
  units 
  of 
  the 
  section 
  at 
  Morrison 
  

   have 
  not 
  been 
  carefully 
  measured, 
  but 
  the 
  estimated 
  

   thicknesses 
  are 
  sufficiently 
  accurate 
  for 
  present 
  pur- 
  

   poses. 
  The 
  classification 
  which 
  seems 
  necessary 
  because 
  

   of 
  the 
  new 
  information 
  is 
  indicated 
  at 
  the 
  left 
  in 
  the 
  

   following 
  section. 
  Explanatory 
  notes 
  and 
  suggested 
  

   changes 
  are 
  in 
  parentheses. 
  

  

  Estimated 
  

   thickness 
  

   in 
  feet 
  

   Section 
  at 
  Morrison, 
  Colorado. 
  

  

  Dakota 
  group, 
  265 
  feet. 
  

  

  1 
  Sandstone, 
  massive, 
  quartzose 
  (the 
  "upper 
  Dakota" 
  

  

  of 
  some 
  geologists) 
  75 
  

  

  2 
  Shale, 
  sandy, 
  dark 
  colored. 
  ("Dakota 
  fire-clay") 
  5 
  

  

  3 
  Sandstone, 
  massive, 
  quartzose, 
  plant-bearing 
  near 
  

   the 
  base, 
  lower 
  2 
  inches 
  filled 
  with 
  carbonized 
  wood, 
  

   seemingly 
  a 
  fossil 
  soil; 
  horizon 
  of 
  plants 
  collected 
  

  

  1 
  Published 
  by 
  permission 
  of 
  the 
  Director 
  of 
  the 
  TJ. 
  S. 
  Geological 
  Survey. 
  

   This 
  paper 
  is 
  followed 
  by 
  one 
  on 
  the 
  Flora 
  of 
  the 
  Morrison 
  Formation 
  by 
  

   F. 
  H. 
  Knowlton. 
  

  

  