﻿14 
  F00TE 
  : 
  GEOLOGY 
  OP 
  MADRAS. 
  

  

  The 
  most 
  westerly 
  accumulation 
  of 
  blown 
  sands 
  observed 
  lies 
  about 
  

   seven 
  miles 
  north-west 
  of 
  Pulicat 
  on 
  the 
  south 
  shore 
  of 
  the 
  Pulicat 
  lake 
  

   north 
  of 
  the 
  village 
  of 
  Pungalum 
  ; 
  it 
  is 
  of 
  small 
  extent, 
  being 
  only 
  a 
  

   mile 
  and 
  a 
  half 
  from 
  east 
  to 
  west 
  and 
  about 
  half 
  a 
  mile 
  at 
  its 
  broadest 
  

   part. 
  From 
  its 
  more 
  than 
  usually 
  reddish 
  color, 
  I 
  am 
  inclined 
  to 
  

   attribute 
  its 
  formation 
  in 
  part 
  to 
  the 
  action 
  of 
  the 
  south-west 
  monsoon 
  

   sweeping 
  over 
  the 
  very 
  sandy 
  surface 
  of 
  the 
  decomposing 
  laterite 
  grit 
  

   beds 
  lying 
  to 
  the 
  south 
  of 
  it. 
  

  

  No 
  blown 
  sands, 
  which 
  were 
  of 
  sufficient 
  size 
  or 
  extent 
  to 
  merit 
  any 
  

   notice, 
  were 
  seen 
  along 
  any 
  of 
  the 
  rivers 
  in 
  the 
  area 
  now 
  treated 
  of. 
  

  

  b. 
  — 
  Soils. 
  

   The 
  soils 
  found 
  within 
  the 
  area 
  here 
  treated 
  of 
  are 
  almost 
  invariably 
  

   formed 
  of 
  the 
  decomposed 
  subsoil, 
  moved 
  about 
  and 
  redistributed 
  by 
  

   the 
  action 
  of 
  the 
  heavy 
  rain-fall 
  to 
  such 
  an 
  extent 
  that 
  in 
  many 
  sections 
  

   they 
  present 
  the 
  appearance 
  of 
  truly 
  sedimentary 
  formations, 
  and 
  in 
  fact 
  

   constitute 
  a 
  link 
  between 
  the 
  truly 
  sedimentary 
  and 
  truly 
  sub-aerial 
  

   deposits. 
  They 
  are 
  almost 
  everywhere 
  sandy 
  or 
  loamy, 
  and 
  on 
  the 
  

   gneissic 
  and 
  lateritic 
  formations 
  of 
  varying 
  shades 
  of 
  red 
  color, 
  

   the 
  intensity 
  depending 
  on 
  the 
  percentage 
  of 
  iron 
  they 
  contain. 
  

  

  On 
  the 
  alluvial 
  formations 
  the 
  soil 
  is 
  generally 
  very 
  pale, 
  reddish 
  

   or 
  brownish-white 
  in 
  color, 
  and 
  consists 
  most 
  frequently 
  of 
  a 
  nearly 
  

   pure 
  sand. 
  

  

  White 
  soda 
  soils 
  were 
  noticed 
  along 
  the 
  eastern 
  branch 
  of 
  the 
  

   Adyar 
  river, 
  which 
  rises 
  in 
  the 
  great 
  Nundiveram 
  tank. 
  

  

  Regur 
  (rigar), 
  or 
  true 
  black-soil, 
  not 
  resulting 
  from 
  tank 
  deposits, 
  

   was 
  observed 
  in 
  one 
  place 
  only 
  near 
  the 
  Arconum 
  railway 
  junction 
  ; 
  and 
  

   there 
  it 
  covers 
  but 
  a 
  small 
  area. 
  

  

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