﻿Belated 
  Sedimentary 
  Surface 
  Forms. 
  257 
  

  

  But 
  even 
  in 
  moist 
  climates 
  very 
  complicated 
  conditions 
  

   may 
  arise 
  which 
  would 
  call 
  for 
  the 
  greatest 
  caution 
  in 
  the 
  

   analysis 
  of 
  ample 
  data, 
  without 
  which 
  no 
  positive 
  results 
  

   could 
  be 
  hoped 
  for. 
  The 
  rift 
  valley 
  of 
  the 
  Rhine, 
  e. 
  g., 
  

   over 
  160 
  miles 
  long 
  between 
  Basel 
  to 
  Bingen, 
  was 
  filled 
  

   to 
  a 
  depth 
  of 
  over 
  100 
  m., 
  43 
  locally 
  even 
  over 
  150 
  m., 
  44 
  

   with 
  silt, 
  sand 
  and 
  gravel 
  by 
  the 
  Rhine 
  and 
  its 
  tribu- 
  

   taries. 
  The 
  Rhine 
  flows 
  from 
  south 
  to 
  north, 
  but 
  mean- 
  

   dered 
  over 
  a 
  large 
  part 
  of 
  the 
  20 
  miles 
  width 
  of 
  the 
  valley, 
  

   and 
  frequently 
  overlapped 
  widely 
  over 
  the 
  fans 
  built 
  

   by 
  its 
  tributaries, 
  each 
  of 
  which, 
  upon 
  emerging 
  from 
  the 
  

   bordering 
  horsts, 
  meandered 
  more 
  or 
  less 
  widely 
  over 
  

   the 
  confines 
  of 
  its 
  fan. 
  An 
  analysis 
  of 
  the 
  ripples 
  of 
  such 
  

   deposits 
  might 
  well 
  meet 
  with 
  insuperable 
  difficulties. 
  

   But 
  it 
  deserves 
  to 
  be 
  attempted 
  and 
  may, 
  when 
  combined 
  

   with 
  careful 
  studies 
  of 
  the 
  composition 
  of 
  the 
  associated 
  

   gravels 
  and 
  other 
  data, 
  yield 
  reliable 
  results 
  which 
  would 
  

   substitute 
  definite 
  geographical 
  conceptions 
  for 
  vague 
  

   notions. 
  

  

  In 
  the 
  Pottsville 
  series 
  of 
  Kentucky, 
  the 
  author 
  

   observed 
  at 
  several 
  localities 
  shaly 
  sandstones 
  in 
  which 
  

   the 
  ripples, 
  covering 
  nearly 
  every 
  layer, 
  showed 
  a 
  grad- 
  

   ual 
  and 
  continuous 
  change 
  of 
  direction 
  from 
  one 
  level 
  to 
  

   the 
  next, 
  reflecting 
  clearly 
  the 
  slow 
  shifting 
  of 
  the 
  current 
  

   in 
  some 
  part 
  of 
  a 
  meandering 
  stream. 
  One 
  mile 
  north- 
  

   east 
  of 
  Oil 
  Springs, 
  Johnson 
  Co., 
  Ky., 
  for 
  instance, 
  the 
  

   following 
  six 
  readings 
  were 
  taken 
  on 
  the 
  best 
  exposed 
  

   surfaces 
  within 
  a 
  thickness 
  of 
  three 
  feet 
  of 
  very 
  thin 
  

   bedded 
  shaly 
  sandstone 
  : 
  

  

  S 
  40 
  E 
  

   S 
  45 
  E 
  

  

  S 
  50 
  E 
  

   S 
  57 
  E 
  

   S 
  70 
  E 
  

   S 
  90 
  E 
  

  

  A 
  number 
  of 
  intervening 
  layers 
  showed 
  rippling 
  too, 
  

   which, 
  in 
  all 
  cases, 
  was 
  in 
  harmony 
  with 
  this 
  general 
  

   arrangement. 
  The 
  wave-length 
  of 
  the 
  ripples 
  varied 
  

   between 
  6-5 
  and 
  7-5 
  cm., 
  and 
  all 
  faced 
  southward. 
  

  

  4. 
  Current-ripples 
  as 
  evidence 
  of 
  exposure. 
  — 
  The 
  

   highly 
  characteristic 
  linguoid 
  ripples, 
  described 
  in 
  Part 
  

  

  43 
  G. 
  E. 
  Lepsius, 
  Das 
  Mainzer 
  Becken, 
  Darmstadt, 
  1883, 
  p. 
  156. 
  

  

  44 
  E. 
  g. 
  160 
  m. 
  at 
  Blodelsheim, 
  in 
  the 
  Upper 
  Alsace: 
  L. 
  Van 
  Werveke, 
  

   Uebersicht 
  ii. 
  d. 
  geol. 
  Bau 
  u. 
  d. 
  geol. 
  Entwickelung 
  des 
  Eeielislandes 
  Elsass- 
  

   Lothringen 
  u. 
  d. 
  Grossh. 
  Baden-Strassburg, 
  1913, 
  p. 
  45. 
  

  

  Am. 
  Jour. 
  Sci.— 
  Fourth 
  Series, 
  Vol. 
  XLVIT, 
  No. 
  280.— 
  April, 
  1919. 
  

  

  18 
  

  

  