﻿T 
  H 
  E 
  

  

  AMERICAN 
  JOURNAL 
  OF 
  SCIENCE 
  

  

  [FOURTH 
  SERIES.] 
  

  

  Aet. 
  XII. 
  — 
  On 
  Ripples 
  and 
  Related 
  Sedimentary 
  Sur- 
  

   face 
  Forms 
  and 
  their 
  Paleo 
  geographic 
  Interpretation; 
  

   by 
  Walter 
  H. 
  Bucher. 
  

  

  Introduction. 
  

  

  Very 
  few 
  of 
  the 
  data, 
  which 
  the 
  geologist 
  can 
  use 
  in 
  his 
  

   attempts 
  to 
  reconstruct 
  the 
  geography 
  of 
  past 
  times, 
  

   allow 
  of 
  but 
  one 
  interpretation. 
  He 
  has 
  to 
  rely 
  on 
  com- 
  

   bining 
  a 
  number 
  of 
  independent 
  data 
  and 
  thus 
  by 
  elimina- 
  

   tion 
  find 
  an 
  approach 
  to 
  the 
  truth. 
  The 
  reliability 
  of 
  his 
  

   conclusions 
  depends, 
  therefore, 
  on 
  the 
  number 
  of 
  data 
  at 
  

   his 
  command 
  and 
  on 
  his 
  ability 
  to 
  correctly 
  interpret 
  

   them. 
  

  

  The 
  paleogeographical 
  importance 
  of 
  fossil 
  ripples 
  was 
  

   early 
  recognized, 
  but 
  until 
  recently 
  little 
  confidence 
  could 
  

   be 
  placed 
  in 
  inferences 
  drawn 
  from 
  them, 
  since 
  such 
  

   information 
  as 
  existed 
  concerning 
  the 
  conditions 
  attend- 
  

   ing 
  their 
  formation 
  was 
  scattered 
  and 
  unsystematic. 
  

  

  If 
  this 
  paper 
  contributes 
  to 
  the 
  understanding 
  and 
  the 
  

   confidence 
  in 
  the 
  interpretation 
  of 
  rippled 
  surfaces 
  and, 
  

   thereby, 
  increases 
  the 
  small 
  number 
  of 
  data 
  by 
  which 
  the 
  

   geologist 
  can 
  check 
  his 
  reconstructions, 
  it 
  has 
  served 
  its 
  

   purpose. 
  

  

  Part 
  I. 
  The 
  Origin 
  of 
  Ripples 
  and 
  related 
  Sedimen- 
  

   tary 
  Surface 
  Forms. 
  

  

  Table 
  of 
  Contents. 
  

   I. 
  Subaqueous 
  current-ripples. 
  

  

  1. 
  The 
  first 
  critical 
  point 
  of 
  current 
  velocity. 
  

  

  2. 
  The 
  first 
  appearance 
  of 
  current 
  ripples. 
  

  

  3. 
  Rhomboid 
  ripples. 
  

  

  Am. 
  Jotjr. 
  Sci.— 
  Fourth 
  Series, 
  Vol. 
  XLVII, 
  No. 
  279.— 
  March, 
  1919. 
  

   11 
  

  

  