﻿IS 
  J: 
  Bucher 
  — 
  Origin 
  of 
  Bipples, 
  and 
  

  

  of 
  this 
  use 
  of 
  ripples 
  in 
  structural 
  geology 
  is 
  offered 
  by 
  

   the 
  controversy 
  of 
  Rothpletz 
  39 
  and 
  Stuchlik 
  40 
  on 
  the 
  

   structure 
  of 
  the 
  Oligocene 
  lignite 
  beds 
  of 
  Peissenberg, 
  

   in 
  the 
  foothills 
  of 
  the 
  Bavarian 
  Alps, 
  which 
  also 
  serves 
  

   as 
  illustration 
  for 
  the 
  fact 
  that, 
  although 
  pointed 
  out 
  long 
  

   ago, 
  41 
  this 
  difference 
  between 
  cast 
  and 
  original 
  is 
  not 
  as 
  

   familiar 
  to 
  geologists 
  as 
  it 
  should 
  be. 
  

  

  Ripples 
  with 
  double 
  and 
  multiple 
  crests 
  are 
  interesting 
  

   abnormalities 
  about 
  which 
  little 
  more 
  is 
  known 
  than 
  their 
  

   existence. 
  42 
  

  

  All 
  oscillation 
  ripples 
  show 
  a 
  more 
  or 
  less 
  perfect 
  

   assortment 
  of 
  grains, 
  with 
  the 
  lightest 
  grains 
  forming 
  

   the 
  crests 
  and 
  the 
  heaviest 
  the 
  bottoms 
  of 
  the 
  troughs. 
  

   The 
  ripples 
  along 
  the 
  shore 
  of 
  any 
  pond 
  usually 
  show 
  

   the 
  dark 
  particles 
  of 
  organic 
  nature, 
  pollen, 
  fragments 
  

   of 
  leaves, 
  soot, 
  etc., 
  lining 
  the 
  crests 
  of 
  the 
  ripples, 
  while 
  

   the 
  troughs 
  are 
  clean 
  sand. 
  Off 
  the 
  west 
  side 
  of 
  the 
  

   island 
  of 
  Bourbon 
  in 
  the 
  Indian 
  ocean, 
  the 
  French 
  

   engineer 
  Siau 
  43 
  observed 
  ripples 
  the 
  crest 
  of 
  which 
  was 
  

   formed 
  by 
  white 
  coral 
  sand, 
  the 
  troughs 
  by 
  black 
  basalt 
  

   sand. 
  The 
  presence 
  of 
  this 
  assortment 
  of 
  grains 
  is 
  per- 
  

   haps 
  the 
  most 
  reliable 
  characteristic 
  of 
  oscillation 
  rip- 
  

   ples. 
  

  

  3. 
  Lines 
  of 
  flow. 
  — 
  The 
  very 
  complicated 
  system 
  of 
  

   stationary 
  vortices 
  which 
  is 
  set 
  up 
  by 
  the 
  oscillating 
  cur- 
  

   rent 
  was 
  studied 
  in 
  a 
  masterly 
  way 
  by 
  G. 
  H. 
  Darwin, 
  

   whose 
  well-known 
  paper 
  may 
  be 
  consulted 
  for 
  details. 
  

   The 
  vortices 
  ascend 
  from 
  either 
  side 
  of 
  the 
  ripple 
  crest, 
  

   rise 
  above 
  it 
  and 
  descend 
  to 
  the 
  center 
  of 
  the 
  trough. 
  

   Here, 
  by 
  combined 
  action, 
  they 
  build 
  up 
  the 
  small 
  central 
  

   ripple 
  so 
  common 
  in 
  oscillation-ripples. 
  Owing 
  to 
  the 
  

  

  39 
  Rothpletz, 
  Die 
  fossilen 
  oberoligocaenen 
  Wellenfurchen 
  des 
  Peissenbergs 
  

   u. 
  ihre 
  Bedeutung 
  fuer 
  den 
  dortigen 
  Bergbau, 
  Sitzungber. 
  math. 
  phys. 
  

   Klasse, 
  Kgl. 
  Bayr. 
  Akad. 
  Wiss., 
  34, 
  pp. 
  371-382, 
  1904. 
  

  

  40 
  Stuchlik, 
  Die 
  Faziesentwickelung 
  d. 
  suedbayrischen 
  Oligocaen-molasse- 
  

   Jahrb. 
  K. 
  K. 
  Geol., 
  Reichsanstalt, 
  Wien, 
  56, 
  1906. 
  

  

  41 
  Jukes 
  and 
  Geikie, 
  Student's 
  Manual 
  of 
  Geology, 
  3d 
  edit., 
  1871, 
  p. 
  63; 
  

   FUchs, 
  Th., 
  Studien 
  ii. 
  Fueoiden 
  u. 
  Hieroglyphen, 
  Denksehr. 
  Wien, 
  Akad. 
  

   Wiss., 
  62, 
  p. 
  372, 
  figs. 
  1 
  and 
  2, 
  1895; 
  Van 
  Hise, 
  C. 
  E., 
  Principles 
  of 
  North 
  

   American 
  pre-Cambrian 
  Geology, 
  16th 
  Ann. 
  Kept, 
  U. 
  S. 
  G. 
  S., 
  pt. 
  I, 
  1896, 
  

   pp. 
  719-721. 
  

  

  e 
  e, 
  g. 
  Forel, 
  1895, 
  vol. 
  2, 
  figs. 
  100 
  and 
  101, 
  p. 
  273; 
  Cornish 
  1901, 
  

   p. 
  194 
  and 
  pi. 
  2, 
  fig. 
  25 
  (excellent 
  photograph). 
  

  

  "The 
  locality 
  is 
  St. 
  Gilles, 
  practically 
  on 
  the 
  westernmost 
  point 
  of 
  the 
  

   island 
  of 
  Bourbon 
  or 
  Reunion, 
  about 
  5 
  miles 
  S.W. 
  of 
  St. 
  Paul 
  (see 
  e.g. 
  the 
  

   small 
  map 
  of 
  Reunion 
  in 
  "La 
  Grande 
  Encyclopedic,") 
  not 
  St. 
  Gilles 
  in 
  the 
  

   Atlantic 
  Ocean, 
  as 
  Pore! 
  stated 
  erroneously 
  in 
  his 
  paper 
  of 
  1883, 
  a 
  state- 
  

   ment, 
  which 
  has 
  found 
  its 
  way 
  into 
  most 
  textbooks. 
  Cf. 
  Comptes 
  Eendus, 
  

   vol. 
  12, 
  p. 
  775. 
  

  

  