﻿354 
  

  

  J. 
  Barrell 
  — 
  The 
  Piedmont 
  Terraces 
  

  

  in 
  certain 
  directions 
  giving 
  current 
  effects, 
  and 
  varia- 
  

   tions 
  in 
  storms 
  and 
  in 
  depth 
  of 
  water 
  modify 
  it 
  from 
  one 
  

   scale 
  to 
  another. 
  

  

  A 
  study 
  of 
  the 
  relation 
  of 
  depth 
  to 
  distance 
  from 
  shore 
  

   for 
  specific 
  types 
  of 
  water 
  bodies 
  gives 
  the 
  following 
  

   results 
  : 
  

  

  Bottom 
  Profiles 
  established 
  oy 
  Wave 
  Action. 
  

   Depths 
  of 
  water 
  in 
  feet. 
  

  

  Distances 
  from 
  shore 
  in 
  miles. 
  

  

  Type 
  of 
  water 
  body 
  5 
  10 
  20 
  80 
  100 
  

  

  Stormy 
  shelf 
  seas 
  95 
  110 
  140 
  300 
  300 
  

  

  Stormy 
  epeiric 
  seas 
  .55 
  70 
  90 
  110 
  110 
  

  

  Quiet 
  epeiric 
  seas 
  35 
  50 
  70 
  90 
  90 
  

  

  Wide 
  lagoons 
  15 
  15 
  

  

  Playa 
  seas 
  to 
  5 
  ... 
  

  

  Fig. 
  15. 
  

  

  Fig. 
  15. 
  — 
  Profile 
  to 
  show 
  that, 
  with 
  a 
  stationary 
  land, 
  erosion 
  occurs 
  

   on 
  all 
  parts 
  of 
  the* 
  profile 
  of 
  equilibrium. 
  

  

  That 
  erosion 
  must 
  take 
  place 
  on 
  all 
  parts 
  of 
  the 
  profile 
  

   of 
  equilibrium, 
  under 
  stationary 
  conditions 
  of 
  land 
  and 
  

   sea, 
  may 
  be 
  shown 
  in 
  the 
  following 
  manner. 
  In 
  fig. 
  15 
  

   let 
  ABODE 
  and 
  A'B'C'D'E' 
  be 
  two 
  consecutive 
  posi- 
  

   tions 
  of 
  the 
  profile 
  of 
  equilibrium. 
  As 
  the 
  curve 
  remains 
  

   the 
  same 
  in 
  form 
  for 
  both 
  positions, 
  the 
  distances 
  AA', 
  

   BB', 
  etc. 
  must 
  be 
  equal. 
  The 
  area 
  of 
  ABB'A' 
  is 
  equal 
  to 
  

   that 
  of 
  a 
  rectangle 
  with 
  the 
  base 
  BB' 
  and 
  height 
  AM, 
  

   and 
  the 
  same 
  relation 
  is 
  true 
  for 
  the 
  other 
  areas. 
  There- 
  

  

  

  