﻿Related 
  Sedimentary 
  Surface 
  Forms. 
  159 
  

  

  (d.) 
  The 
  wave-length 
  decreases 
  with 
  increasing 
  salin- 
  

   ity, 
  i. 
  e. 
  density 
  of 
  the 
  water, 
  not, 
  however, 
  as 
  a 
  linear 
  

   function. 
  The 
  higher 
  the 
  concentration, 
  the 
  greater 
  is 
  

   the 
  decrease. 
  

  

  (e.) 
  The 
  wave-length 
  increases 
  with 
  rising 
  tempera- 
  

   ture. 
  This 
  increase 
  is 
  not 
  due 
  to 
  the 
  effect 
  of 
  tempera- 
  

   ture 
  on 
  the 
  density 
  of 
  the 
  water: 
  for 
  it 
  continues 
  uni- 
  

   formly 
  from 
  below 
  to 
  beyond 
  4°C. 
  

  

  (d.) 
  and 
  (e.) 
  are 
  due 
  to 
  the 
  changes 
  in 
  the 
  viscosity 
  of 
  

   the 
  liquid. 
  The 
  viscosity 
  of 
  solutions 
  decreases 
  with 
  

   rising 
  temperature 
  and 
  increases 
  with 
  increasing 
  salin- 
  

   ity. 
  The 
  higher 
  the 
  concentration, 
  the 
  more 
  rapid 
  the 
  

   increase 
  of 
  viscosity. 
  The 
  curves 
  constructed 
  by 
  Hah- 
  

   mann 
  after 
  his 
  experiments, 
  showing 
  the 
  relations 
  

   between 
  wave-length, 
  density 
  and 
  temperature, 
  corre- 
  

   spond 
  directly 
  to 
  those 
  showing 
  viscosity 
  as 
  a 
  function 
  

   of 
  temperature 
  and 
  density, 
  except 
  that 
  they 
  are 
  the 
  

   reverse 
  of 
  the 
  latter 
  (for 
  details 
  compare 
  Hahmann, 
  pp. 
  

   667 
  to 
  668). 
  The 
  wave-length, 
  therefore, 
  is 
  inversely 
  

   proportional 
  to 
  the 
  viscosity 
  of 
  the 
  liquid. 
  

  

  (/.) 
  The 
  wave-length 
  increases 
  with 
  increasing 
  size 
  

   of 
  the 
  grain, 
  whether 
  in 
  linear 
  proportion 
  or 
  not, 
  could 
  

   not 
  be 
  determined. 
  In 
  case 
  of 
  mixtures, 
  the 
  largest 
  

   grains, 
  if 
  present 
  in 
  sufficient 
  numbers, 
  determine 
  the 
  

   wave-length 
  (Hahmann, 
  pp. 
  648-9). 
  Fine 
  grains 
  mixed 
  

   with 
  coarser 
  material 
  help 
  greatly 
  to 
  increase 
  the 
  sharp- 
  

   ness 
  of 
  the 
  crest 
  without, 
  however, 
  affecting 
  the 
  wave- 
  

   length. 
  

  

  (g.) 
  The 
  wave-length 
  is 
  independent 
  of 
  the 
  density 
  

   of 
  the 
  debris. 
  Hahmann 
  mixed 
  iron-filings 
  and 
  fine 
  sand 
  

   in 
  equal 
  proportions 
  and 
  obtained 
  the 
  same 
  wave-length 
  

   as 
  with 
  fine 
  sand 
  along 
  (pp. 
  653-5). 
  (Spec. 
  gr. 
  2-6 
  vs. 
  

   7-5!). 
  

  

  (h.) 
  The 
  wave-length 
  appeared 
  to 
  be 
  independent 
  of 
  

   the 
  thickness 
  of 
  the 
  bed 
  of 
  sand 
  (p. 
  655). 
  

  

  (i.) 
  No 
  data 
  exist 
  concerning 
  the 
  influence 
  of 
  the 
  

   shape 
  of 
  the 
  grains. 
  

  

  5. 
  The 
  formation 
  of 
  current-ripples. 
  13 
  

  

  From 
  the 
  foregoing 
  we 
  can 
  describe 
  the 
  formation 
  of 
  

   current-ripples 
  as 
  the 
  establishment 
  of 
  a 
  layer 
  of 
  vortices 
  

   with 
  a 
  horizontal 
  axis, 
  separating 
  the 
  essentially 
  rigid 
  

   bed 
  from 
  the 
  liquid. 
  The 
  resulting 
  arrangement 
  of 
  flow 
  

  

  13 
  See 
  also 
  p. 
  199 
  ff. 
  

  

  