﻿M8 
  Bucher 
  — 
  Origin 
  of 
  Ripples, 
  and 
  

  

  the 
  troughs 
  by 
  the 
  receding 
  waters 
  which 
  exposed 
  the 
  

   crests. 
  

  

  3. 
  The 
  relation 
  existing 
  between 
  the 
  trend 
  of 
  oscilla- 
  

   tion-ripples 
  and 
  geographical 
  conditions, 
  too, 
  offers 
  a 
  

   highly 
  complex 
  problem. 
  In 
  practical 
  application 
  it 
  

   presents 
  itself 
  in 
  this 
  form: 
  Why 
  do 
  the 
  ripples 
  of 
  one 
  

   formation 
  show 
  a 
  pronounced 
  parallelism, 
  while 
  others 
  

   do 
  not? 
  

  

  In 
  the 
  case 
  of 
  parallel 
  ripples, 
  others 
  were 
  either 
  not 
  

   formed 
  or 
  not 
  preserved. 
  

  

  (a) 
  That 
  they 
  were 
  not 
  formed 
  might 
  be 
  due 
  (1) 
  to 
  

   practical 
  absence 
  of 
  winds 
  from 
  other 
  directions, 
  as 
  under 
  

   trade 
  wind 
  or 
  monsoon 
  conditions; 
  or 
  (2) 
  that 
  only 
  

   waves 
  from 
  one 
  direction 
  i 
  i 
  touched 
  bottom. 
  ' 
  ' 
  

  

  (b) 
  Of 
  the 
  factors 
  favoring 
  the 
  preservation 
  of 
  rip- 
  

   ples, 
  outlined, 
  only 
  one 
  may 
  have 
  a 
  selective 
  effect. 
  

  

  If 
  the 
  form 
  ratio 
  of 
  the 
  waterbody 
  is 
  such 
  that 
  only 
  

   the 
  largest 
  waves 
  stir 
  the 
  bottom 
  sufficiently 
  so 
  as 
  to 
  pro- 
  

   vide 
  the 
  sediment 
  with 
  which 
  to 
  cover 
  and 
  preserve 
  rip- 
  

   ples, 
  the 
  bottom 
  is, 
  for 
  long 
  periods, 
  exposed 
  to 
  the 
  

   rippling 
  action 
  of 
  the 
  smaller 
  waves. 
  The 
  smaller 
  rip- 
  

   ples 
  formed 
  by 
  them, 
  however, 
  will 
  not 
  ordinarily 
  be 
  pre- 
  

   served, 
  because 
  they 
  are 
  nearly 
  always 
  replaced 
  by 
  the 
  

   larger 
  ones 
  resulting 
  from 
  the 
  action 
  of 
  the 
  exceptional 
  

   waves. 
  According 
  to 
  Forel's 
  experiments, 
  these, 
  on 
  the 
  

   other 
  hand, 
  will 
  not 
  be 
  changed, 
  either 
  in 
  wave-length 
  or 
  

   orientation, 
  by 
  minor 
  agitations 
  of 
  the 
  sea-bottom 
  off- 
  

   ering 
  in 
  direction 
  up 
  to 
  45° 
  from 
  their 
  own 
  and, 
  conse- 
  

   quently, 
  are 
  by 
  far 
  the 
  most 
  likely 
  to 
  be 
  preserved. 
  

  

  Along 
  any 
  coast 
  facing 
  the 
  open 
  ocean, 
  the 
  direction 
  

   from 
  which 
  the 
  largest 
  waves 
  come 
  will 
  always 
  be 
  more 
  

   or 
  less 
  at 
  right 
  angles 
  to 
  the 
  shore. 
  Even 
  if 
  the 
  direction 
  

   of 
  greatest 
  fetch 
  of 
  the 
  wind 
  should 
  differ 
  considerably 
  

   from 
  that 
  of 
  a 
  right 
  angle, 
  the 
  waves 
  would 
  break 
  so 
  far 
  

   from 
  the 
  shore 
  as 
  to 
  turn 
  them 
  into 
  such 
  a 
  position 
  in 
  

   shallower 
  water. 
  

  

  In 
  shallow 
  seas 
  of 
  relatively 
  uniform 
  depth 
  and 
  small 
  

   form-ratio, 
  the 
  bottom 
  of 
  which 
  is 
  reached 
  practically 
  

   everywhere 
  by 
  most 
  waves, 
  such 
  as 
  probably 
  yielded 
  the 
  

   Largest 
  part 
  of 
  our 
  marine 
  sedimentary 
  record, 
  this 
  

   breaking 
  and 
  turning 
  of 
  the 
  wave-front 
  is 
  confined 
  in 
  its 
  

   effects 
  to 
  but 
  a 
  \ 
  civ 
  narrow 
  zone. 
  Throughout 
  the 
  largest 
  

   portion 
  of 
  the 
  sediments 
  of 
  such 
  large 
  or 
  small 
  embay- 
  

   ments 
  and 
  gulfs 
  the 
  Length 
  of 
  fetch 
  of 
  the 
  wind 
  would 
  

  

  