﻿26 
  FOOTE 
  : 
  GEOLOGY 
  OF 
  MADRAS. 
  

  

  the 
  highly 
  turbid 
  waters 
  allowed 
  to 
  settle 
  their 
  sediment 
  in 
  tanks, 
  

   almost 
  every 
  part 
  of 
  the 
  sediment 
  they 
  bring 
  from 
  inland 
  would 
  be 
  

   carried 
  into 
  the 
  backwaters 
  or 
  out 
  to 
  sea 
  to 
  be 
  scattered 
  up 
  and 
  down 
  

   the'coast 
  according 
  to 
  the 
  set 
  of 
  the 
  great 
  periodical 
  coast-currents. 
  

  

  The 
  great 
  quantity 
  of 
  water 
  drawn 
  from 
  the 
  rivers 
  for 
  irrigation 
  

   purposes 
  must 
  materially 
  retard 
  the 
  scouring 
  action 
  by 
  which 
  these 
  

   rivers 
  deepen 
  their 
  beds, 
  which 
  would 
  otherwise 
  probably 
  soon 
  become 
  

   so 
  deep 
  as 
  to 
  be 
  useless 
  for 
  ordinary 
  irrigation 
  purposes. 
  Such 
  a 
  state 
  of 
  

   things 
  on 
  a 
  large 
  scale 
  was 
  taking 
  place 
  in 
  the 
  Coleroon 
  river, 
  when 
  the 
  

   Government 
  stepped 
  in 
  and 
  built 
  the 
  anicut, 
  or 
  dam, 
  across 
  the 
  river 
  

   at 
  the 
  head 
  of 
  the 
  (Seringham) 
  Sri 
  Rungum 
  island, 
  near 
  Trichinopoly. 
  

  

  The 
  positions 
  of 
  the 
  various 
  alluvial 
  valleys 
  are 
  clearly 
  shown 
  in 
  the 
  

   long 
  section 
  accompanying 
  this 
  report 
  (PI. 
  A) 
  . 
  

  

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  20 
  ) 
  

  

  