﻿Related 
  Sedimentary 
  Surface 
  Forms. 
  153 
  

  

  system 
  of 
  dunes." 
  "In 
  certain 
  experiments 
  on 
  flume 
  

   traction 
  a 
  slow 
  current 
  moving 
  over 
  a 
  smooth 
  channel 
  bed 
  

   of 
  wood, 
  swept 
  along 
  a 
  small 
  quantity 
  of 
  sand. 
  With 
  

   increase 
  of 
  the 
  load 
  of 
  sand, 
  local 
  deposits 
  were 
  induced, 
  

   which 
  took 
  the 
  form 
  of 
  thin 
  straggling 
  patches, 
  similar 
  

   to 
  one 
  another 
  in 
  outline 
  and 
  separated 
  by 
  approximately 
  

   equal 
  bare 
  spaces." 
  Baschin 
  (1899, 
  p. 
  420) 
  has 
  called 
  

   attention 
  to 
  a 
  similar 
  arrangement 
  of 
  wind-blown 
  sand 
  

   in 
  parallel 
  elongated 
  patches, 
  as 
  it 
  may 
  at 
  times 
  be 
  

   observed 
  on 
  asphalted 
  streets. 
  

  

  3. 
  Rhomboid 
  ripples. 
  

  

  Still 
  more 
  suggestive 
  is 
  a 
  peculiar 
  form 
  of 
  current- 
  

   ripples 
  that 
  was 
  described 
  by 
  H. 
  Engels 
  (1905), 
  the 
  head 
  

   of 
  the 
  laboratory 
  of 
  Eiver 
  Engineering 
  at 
  Dresden. 
  In 
  

   his 
  experiments 
  the 
  first 
  effect 
  of 
  transportation 
  by 
  a 
  

   uniform 
  current 
  was 
  the 
  formation 
  of 
  small 
  rhomb 
  oidal, 
  

   scale-like 
  tongues 
  of 
  sand, 
  arranged 
  in 
  a 
  reticular 
  pattern, 
  

   strikingly 
  resembling 
  that 
  of 
  the 
  scales 
  of 
  a 
  Ganoid. 
  

   Each 
  tongue 
  has 
  one 
  acute 
  angle 
  pointing 
  down 
  stream, 
  

   formed 
  by 
  two 
  steep 
  leesides, 
  while 
  the 
  other, 
  pointing 
  up 
  

   stream, 
  is 
  formed 
  by 
  the 
  gentle 
  slope 
  extending 
  into 
  the 
  

   reentrant 
  angle 
  of 
  the 
  leesides 
  of 
  two 
  tongues 
  of 
  the 
  

   following, 
  alternating 
  row. 
  4 
  I 
  suggest 
  the 
  name 
  rhom- 
  

   boid 
  {current-) 
  ripple 
  for 
  this 
  peculiar 
  form 
  which 
  must 
  

   not 
  be 
  confused 
  with 
  polygonal 
  interference 
  ripples 
  (cf. 
  

   p. 
  190 
  ff.). 
  In 
  Engel's 
  experiments, 
  with 
  increasing- 
  

   velocity 
  of 
  the 
  current, 
  common 
  current 
  ripples 
  took 
  

   their 
  place. 
  

  

  4. 
  Data 
  concerning 
  current-ripples. 
  

  

  1. 
  Ground 
  plan. 
  5 
  — 
  Where 
  developed 
  over 
  large 
  sur- 
  

   faces 
  by 
  a 
  current 
  of 
  uniform 
  direction, 
  as 
  on 
  tidal 
  flats, 
  

   current-ripples 
  consist 
  of 
  numerous 
  essentially 
  parallel, 
  

   long, 
  narrow, 
  more 
  or 
  less 
  equidistant 
  ridges, 
  trending 
  

   in 
  straight 
  or 
  gently 
  curved 
  lines 
  at 
  right 
  angles 
  to 
  the 
  

   current, 
  anastomosing 
  frequently, 
  in 
  general 
  offering 
  a 
  

  

  4 
  Kindle 
  (1917) 
  figures 
  on 
  pi. 
  19B 
  a 
  good 
  example 
  of 
  the 
  same 
  type 
  

   observed 
  on 
  a 
  beach 
  in 
  Lake 
  Erie. 
  The 
  only 
  case 
  of 
  this 
  very 
  striking 
  

   pattern 
  that 
  came 
  to 
  my 
  observation, 
  I 
  was 
  unable 
  at 
  the 
  time 
  (1913) 
  to 
  

   study 
  in 
  detail. 
  It 
  was 
  in 
  one 
  of 
  the 
  distributaries 
  of 
  a 
  waste 
  delta 
  built 
  

   into 
  Cobalt 
  Lake, 
  Ontario, 
  from 
  the 
  flumes 
  of 
  the 
  plant 
  of 
  the 
  Nipissing 
  

   Mining 
  Co. 
  

  

  5 
  Good 
  illustrations: 
  Brown, 
  1911, 
  p. 
  540, 
  fig. 
  3; 
  Epry, 
  1913, 
  pi. 
  1, 
  

   fig. 
  2; 
  Scott, 
  W. 
  B., 
  An 
  Introduction 
  to 
  Geology, 
  2d 
  ed., 
  1909, 
  fig. 
  ]27, 
  

   p. 
  248; 
  Kindle, 
  1917, 
  pi. 
  7, 
  9-11. 
  

  

  