﻿Related 
  Sedimentary 
  Surface 
  Forms. 
  197 
  

  

  water-formed 
  ripples, 
  while 
  it 
  may 
  be 
  very 
  much 
  smaller 
  

   in 
  wind-formed 
  ripples. 
  Thus, 
  among 
  the 
  values 
  given 
  in 
  

   table 
  2. 
  we 
  find 
  the 
  indices 
  4, 
  5, 
  6, 
  while 
  Cornish 
  reports 
  

   that 
  in 
  the 
  long 
  train 
  of 
  moderately 
  large 
  ripples 
  meas- 
  

   ured 
  on 
  dune 
  sand 
  north 
  of 
  Ismailia, 
  Egypt, 
  the 
  individ- 
  

   ual 
  ratios 
  varied 
  from 
  11-3 
  to 
  54 
  (exceptionally). 
  58 
  

   Kindle 
  59 
  found 
  on 
  the 
  moulds 
  of 
  two 
  examples 
  of 
  water- 
  

   made 
  ripple 
  mark 
  taken 
  respectively 
  in 
  the 
  St. 
  Lawrence 
  

   river 
  and 
  Lake 
  Ontario, 
  the 
  indices 
  4 
  and 
  6-3, 
  while 
  the 
  

   ratios 
  of 
  two 
  examples 
  of 
  moulds 
  of 
  wind-made 
  ripples 
  

   taken 
  at 
  Wellington 
  were 
  24 
  and 
  25. 
  "The 
  sharp 
  con- 
  

   trast 
  in 
  the 
  height 
  of 
  the 
  crest 
  in 
  dune 
  ripples 
  and 
  in 
  sub- 
  

   aqueous 
  ripples 
  is 
  illustrated 
  by 
  the 
  profiles 
  of 
  examples 
  

   of 
  both 
  types 
  which 
  have 
  about 
  the 
  same 
  amplitude" 
  

   given 
  in 
  figs. 
  2 
  and 
  3 
  of 
  his 
  paper. 
  

  

  "While 
  it 
  is 
  desirable 
  to 
  have 
  this 
  rule 
  confirmed 
  by 
  a 
  

   much 
  greater 
  number 
  of 
  observations, 
  we 
  are 
  certainly 
  

   justified 
  in 
  applying 
  it 
  at 
  least 
  tentatively 
  to 
  fossil 
  rip- 
  

  

  The 
  wave-length 
  of 
  eolian 
  ripples 
  ranges 
  from 
  about 
  

   2 
  cm. 
  to 
  100 
  cm. 
  ; 
  they 
  were 
  even 
  reported 
  as 
  large 
  as 
  

   200 
  cm. 
  (Baschin, 
  1. 
  c.j. 
  It 
  is, 
  however, 
  highly 
  probable 
  

   that 
  these 
  largest 
  ones, 
  at 
  least, 
  were 
  not 
  formed 
  inde- 
  

   pendently, 
  but 
  owe 
  their 
  origin 
  to 
  conditions 
  presently 
  

   to 
  be 
  described. 
  

  

  The 
  wave-length 
  of 
  eolian 
  ripples 
  increases 
  with 
  the 
  

   velocity 
  of 
  the 
  wind 
  (Hahmann, 
  1912, 
  p. 
  658-659). 
  From 
  

   Sokolow's 
  observations 
  it 
  seemed 
  to 
  follow 
  that 
  the 
  wave 
  

   length 
  also 
  increases 
  with 
  the 
  size 
  of 
  the 
  grains 
  ; 
  

   Hahmann 
  's 
  experiments, 
  however, 
  seemed 
  to 
  prove 
  the 
  

   opposite. 
  He 
  assumed 
  that 
  in 
  his 
  experiments 
  the 
  air 
  

   blast 
  was 
  not 
  allowed 
  to 
  act 
  long 
  enough 
  on 
  the 
  sand. 
  

   This 
  explanation 
  is 
  plausible, 
  but 
  it 
  remains 
  to 
  be 
  veri- 
  

   fied. 
  If 
  my 
  interpretation 
  of 
  the 
  influence 
  of 
  the 
  size 
  of 
  

   the 
  grain 
  on 
  the 
  inclination 
  of 
  the 
  weather 
  side 
  is 
  correct, 
  

   there 
  does 
  not 
  seem 
  to 
  be 
  an 
  inherent 
  reason 
  why 
  the 
  

   effect 
  should 
  not 
  be 
  in 
  air 
  the 
  reverse 
  of 
  that 
  in 
  water. 
  

  

  A 
  very 
  important 
  series 
  of 
  observations 
  was 
  recently 
  

   published 
  by 
  W. 
  J. 
  H. 
  King 
  (1916). 
  He 
  observed 
  on 
  the 
  

   lee 
  of 
  some 
  stones 
  rippling 
  of 
  larger 
  amplitude 
  super- 
  

  

  jm, 
  On 
  Desert 
  Dunes 
  bordering 
  the 
  Nile 
  Delta, 
  ibid., 
  15, 
  pp. 
  27-2^, 
  

   1900. 
  H 
  ' 
  

  

  39 
  Kindle, 
  E. 
  M., 
  Eeeent 
  and 
  fossil 
  ripple-mark, 
  Geol. 
  Surv. 
  Canada, 
  Mus. 
  

   Bull, 
  25, 
  p. 
  12, 
  1917. 
  

  

  Air. 
  Jour. 
  Sci.— 
  Fourth 
  Series, 
  Vol. 
  XLVII. 
  No. 
  279.— 
  March, 
  1919. 
  

  

  