﻿INTROIMVTION 
  TO 
  IJOTANY 
  

  

  Rapidly 
  running 
  surface 
  water 
  often 
  carries 
  away 
  part 
  01 
  

   all 
  of 
  the 
  fertile 
  soil. 
  1 
  In 
  grasslands, 
  meadows, 
  and 
  foreMed 
  

   areas 
  surface 
  water 
  is 
  retarded 
  in 
  its 
  rate 
  of 
  flow, 
  and 
  conse- 
  

   quently 
  does 
  not 
  carry 
  away 
  much 
  soil. 
  In 
  regions 
  that 
  were 
  

   once 
  forested 
  and' 
  from 
  which 
  the 
  timber 
  has 
  now 
  been 
  largely 
  

  

  FIG. 
  230. 
  Erosion 
  of 
  the 
  soil 
  following 
  removal 
  of 
  the 
  forest 
  

  

  This 
  land 
  was 
  covered 
  with 
  a 
  heavy 
  pine 
  forest 
  ami 
  had 
  a 
  rich 
  soil, 
  \\hich 
  was 
  

  

  held 
  upon 
  the 
  forest 
  Iloor. 
  When 
  the 
  timber 
  was 
  removed, 
  erosion 
  soon 
  eiit 
  

  

  ditches 
  through 
  the 
  pasture 
  land, 
  and 
  part 
  of 
  the 
  rich 
  soil 
  \\as 
  \\ashed 
  away 
  

  

  removed, 
  the 
  surface 
  water 
  soon 
  erodes 
  ditches 
  ( 
  li^. 
  - 
  : 
  >0), 
  

   which, 
  with 
  rapidly 
  deepening 
  channels 
  and 
  developing 
  tribu- 
  

   taries, 
  will 
  in 
  a 
  few 
  years 
  carry 
  away 
  much 
  of 
  the 
  fertile 
  soil 
  

  

  V 
  / 
  */ 
  

  

  of 
  the 
  forest 
  Hoor. 
  After 
  forest 
  I 
  ires, 
  which 
  themselves 
  destroy 
  

   much 
  of 
  the 
  humus 
  of 
  the 
  forest 
  soils, 
  the 
  surface 
  water, 
  

   which 
  is 
  no 
  longer 
  retarded 
  and 
  absorbed 
  by 
  humus. 
  Hows 
  

  

  1 
  " 
  Soil 
  Erosion, 
  ' 
  Jlnlklin 
  71, 
  Bureau 
  of 
  Soils, 
  U.S. 
  Dept. 
  Ayr., 
  1911. 
  

  

  