﻿Belated 
  Sedimentary 
  Surface 
  Forms. 
  203 
  

  

  existence 
  of 
  similar 
  waves 
  at 
  the 
  contact 
  of 
  two 
  immis- 
  

   cible 
  liquids 
  of 
  different 
  specific 
  gravity 
  and 
  opposite 
  

   direction 
  of 
  flow 
  was 
  demonstrated 
  by 
  0. 
  Reynolds 
  in 
  a 
  

   very 
  elegant 
  experiment. 
  73 
  

  

  A 
  remarkable 
  observation 
  was 
  published 
  by 
  Geinitz. 
  74 
  

   In 
  many 
  brick 
  factories 
  the 
  wet 
  clay 
  is 
  formed 
  by 
  a 
  press 
  

   into 
  long 
  bars 
  and 
  then 
  cnt 
  to 
  the 
  proper 
  size 
  by 
  means 
  

   of 
  a 
  wire, 
  moving 
  much 
  like 
  the 
  blade 
  in 
  a 
  breadcutting 
  

   machine. 
  Geinitz 
  observed 
  that 
  this 
  wire 
  does 
  not 
  cut 
  a 
  

   smooth 
  surface, 
  but 
  passes 
  through 
  the, 
  clay 
  in 
  a 
  sinuous 
  

   curve, 
  producing 
  on 
  the 
  surface 
  of 
  the 
  cut 
  a 
  pattern 
  

   exactly 
  analogous 
  to 
  that 
  of 
  current-ripples, 
  showing 
  the 
  

   same 
  anastomosing, 
  gently 
  curved 
  ridges 
  with 
  a 
  steep 
  

   and 
  a 
  gentle 
  side, 
  and 
  a 
  wave-length 
  from 
  crest 
  to 
  crest 
  

   of 
  0-14 
  to 
  0-2 
  cm. 
  The 
  steep 
  side, 
  however, 
  faced 
  the 
  

   wire, 
  that 
  is, 
  " 
  up-stream. 
  " 
  

  

  Geinitz 
  called 
  attention 
  to 
  the 
  delicate 
  ruffling 
  of 
  the 
  

   surface 
  of 
  schistosity 
  of 
  many 
  slates, 
  which 
  may 
  repre- 
  

   sent 
  an 
  analogous 
  phenomenon 
  of 
  friction. 
  75 
  

  

  Another 
  no 
  less 
  remarkable 
  observation 
  is 
  reported 
  

   by 
  V. 
  Cornish. 
  76 
  On 
  steep 
  roads 
  from 
  the 
  Saddlestone 
  

   Slate 
  Quarry 
  and 
  Cove 
  Quarry, 
  Coniston, 
  Lanes., 
  sledges 
  

   are 
  used 
  to 
  convey 
  the 
  slate 
  down 
  to 
  the 
  railway, 
  the 
  load 
  

   for 
  a 
  sledge 
  being 
  half 
  a 
  ton. 
  The 
  sledges 
  are 
  only 
  

   dragged 
  downhill, 
  each, 
  when 
  empty, 
  being 
  placed 
  in 
  the 
  

   cart 
  to 
  which 
  on 
  the 
  down 
  journey 
  it 
  acts 
  as 
  a 
  drag. 
  

   These 
  sledges 
  produce 
  on 
  the 
  road 
  undulations 
  of 
  a 
  sym- 
  

   metrical 
  and 
  rounded 
  form, 
  resembling 
  a 
  curve 
  of 
  sines. 
  

   Their 
  average 
  wave-length 
  is 
  14' 
  9" 
  for 
  both 
  roads, 
  while 
  

   their 
  height 
  averages 
  7*5". 
  The 
  length 
  of 
  the 
  sledge- 
  

   runners 
  is 
  4' 
  7". 
  Similar 
  undulations 
  of 
  nearly 
  the 
  same 
  

   dimensions 
  were 
  observed 
  by 
  Cornish 
  on 
  snow-covered 
  

   roads 
  in 
  Canada, 
  where 
  they 
  are 
  called 
  "cahots." 
  For 
  

  

  73 
  Phil. 
  Trans. 
  Roy. 
  Soc, 
  London, 
  vol. 
  174, 
  pp. 
  943-944, 
  1884. 
  

  

  74 
  Geinitz, 
  E., 
  Ripplemarks 
  auf 
  Ziegelsteinen, 
  Centralbl. 
  f. 
  Min., 
  etc., 
  1911, 
  

   p. 
  640-643 
  (with 
  illustrations). 
  

  

  75 
  This 
  rippling 
  of 
  the 
  cleavage 
  surface 
  may 
  attain 
  larger 
  dimensions 
  in 
  

   slates 
  and 
  schists 
  (cf. 
  Ilenke, 
  Zeitscher. 
  Deutsch. 
  Geol. 
  Ges. 
  Monatsberichte, 
  

   1911, 
  p. 
  104). 
  True 
  ripple-marks 
  must, 
  however, 
  not 
  be 
  mistaken 
  for 
  it 
  in 
  

   rocks 
  showing 
  slaty 
  cleavage 
  in 
  argillaceous 
  layers. 
  For 
  an 
  interesting 
  dis- 
  

   cussion 
  see 
  Krause, 
  Zeitschr. 
  Deutsch. 
  Geol. 
  Ges. 
  Monatsberichte, 
  1911, 
  p. 
  

   196-202. 
  

  

  Whether 
  the 
  peculiar 
  pattern, 
  found 
  commonly 
  on 
  the 
  surface 
  of 
  the 
  layers 
  

   of 
  the 
  so-called 
  " 
  Wellenkalk 
  ' 
  ' 
  of 
  the 
  European 
  Trias 
  may 
  be 
  ascribed 
  to 
  

   the 
  same 
  cause, 
  as 
  Geinitz 
  suggests, 
  appears 
  quite 
  doubtful. 
  

  

  76 
  Cornish, 
  Vaughan, 
  On 
  Eegular 
  Undulations 
  produced 
  in 
  a 
  Road 
  by 
  the 
  

   use 
  of 
  sledges, 
  Brit. 
  Assoc. 
  Adv. 
  Sci., 
  Report, 
  1902, 
  p. 
  730-731; 
  1903, 
  

   p. 
  314 
  and 
  plate 
  10 
  (excellent 
  photograph). 
  

  

  