﻿C. 
  Keyes 
  — 
  A 
  Rotating 
  Straticulate 
  Spheroid. 
  109 
  

  

  As 
  is 
  well 
  known 
  the 
  property 
  by 
  which 
  clays 
  or 
  shales 
  

   slip 
  with 
  greater 
  ease 
  in 
  some 
  directions 
  than 
  in 
  others 
  

   is 
  due 
  primarily 
  to 
  the 
  micaceous 
  or 
  lamellar 
  character 
  

   of 
  the 
  components. 
  "Whether 
  the 
  shale 
  beds 
  be 
  thick 
  or 
  

   thin 
  the 
  superior 
  proneness 
  to 
  glide 
  in 
  a 
  direction 
  paral- 
  

   lel 
  to 
  the 
  original 
  bedding 
  planes 
  persists. 
  This 
  ready 
  

   movement 
  in 
  shales 
  is 
  essentially 
  identical 
  with 
  the 
  

   "flow" 
  of 
  crystalline 
  rocks 
  at 
  great 
  depths 
  and 
  under 
  

   great 
  pressure. 
  It 
  is 
  strictly 
  intermolar 
  motion. 
  It 
  

   takes 
  place 
  not 
  alone 
  in 
  thick 
  beds 
  of 
  shale 
  but 
  in 
  the 
  thin 
  

   partings 
  between 
  brittle 
  formations. 
  It 
  is 
  apparent 
  in 
  

   the 
  thinnest 
  film 
  separating 
  limestone 
  and 
  sandstone 
  beds. 
  

   The 
  evidences 
  of 
  intermolar 
  movement 
  are 
  particularly 
  

   noticeable 
  in 
  sections 
  in 
  which 
  there 
  are 
  great 
  succes- 
  

   sions 
  of 
  thin 
  limestone 
  and 
  shale 
  layers. 
  The 
  Coal 
  

   Measures 
  in 
  Kansas, 
  Iowa, 
  or 
  Maryland 
  afford 
  illumi- 
  

   nating 
  examples. 
  

  

  Experimentally 
  the 
  straticulate 
  structures 
  and 
  the 
  

   deformative 
  conditions 
  in 
  nature 
  are 
  capable 
  of 
  very 
  

   close 
  if 
  not 
  exact 
  reproduction 
  in 
  the 
  arts. 
  Modern 
  

   newspaper 
  rolls 
  as 
  they 
  leave 
  the 
  mill 
  display 
  some 
  

   especially 
  instructive 
  tectonic 
  potentialities. 
  Compared 
  

   with 
  the 
  enormously 
  thick 
  Appalachian 
  section 
  of 
  alter- 
  

   nating 
  limestones 
  and 
  shales 
  the 
  paper 
  itself 
  is 
  analogous 
  

   to 
  the 
  rigid 
  layers 
  and 
  the 
  films 
  between 
  to 
  the 
  shale 
  

   partings. 
  The 
  chief 
  distinction 
  between 
  the 
  phenomenon 
  

   in 
  nature 
  and 
  in 
  the 
  arts 
  is 
  that 
  the 
  paper 
  is 
  relatively 
  

   enormously 
  tough 
  and 
  hence 
  cannot 
  readily 
  respond 
  to 
  

   rupture 
  strains 
  as 
  do 
  rock-layers. 
  The 
  rollpaper 
  is 
  not 
  

   tightly 
  wound, 
  but 
  the 
  winding 
  process 
  is 
  done 
  under 
  a 
  

   certain 
  measureable 
  tension, 
  which 
  is 
  retained 
  to 
  a 
  very 
  

   marked 
  degree 
  long 
  after 
  the 
  roll 
  is 
  released 
  from 
  the 
  

   spindle. 
  This 
  actual 
  or 
  potential 
  stress 
  is 
  perhaps 
  never 
  

   entirely 
  relieved 
  until 
  the 
  roll 
  is 
  finally 
  used 
  on 
  the 
  print- 
  

   ing 
  press. 
  

  

  Contrary 
  to 
  expectations, 
  the 
  unwinding 
  of 
  the 
  paper 
  

   roll 
  on 
  the 
  press, 
  or 
  its 
  slower 
  revolution 
  in 
  its 
  wrap- 
  

   per, 
  does 
  not 
  uniformly 
  relieve 
  the 
  original 
  stresses. 
  

   Because 
  of 
  slight 
  local 
  differences 
  in 
  the 
  texture 
  of 
  the 
  

   paper, 
  in 
  thickness 
  of 
  the 
  sheet, 
  in 
  direction 
  of 
  revolution, 
  

   or 
  in 
  drying 
  out 
  of 
  the 
  original 
  moist 
  condition, 
  the 
  

   layers 
  of 
  paper 
  locally 
  buckle. 
  Ordinarily 
  this 
  yielding 
  

   would 
  take 
  place 
  outwardly 
  but 
  the 
  strong 
  firmly 
  glued 
  

   wrapper 
  prevents 
  relief 
  in 
  that 
  direction. 
  The 
  result 
  is 
  

  

  