﻿38 
  FOOTE 
  : 
  GEOLOGY 
  OF 
  MADRAS. 
  

  

  but 
  in 
  the 
  western 
  and 
  southern 
  parts 
  of 
  the 
  area 
  from 
  Callicoo- 
  

   pum 
  and 
  Mittanemali 
  ( 
  Metnavilly 
  of 
  map) 
  to 
  Avadi, 
  and 
  thence 
  on 
  

   to 
  close 
  to 
  the 
  south-east 
  of 
  the 
  Red 
  Hills 
  tank, 
  the 
  rising- 
  grounds 
  are 
  

   in 
  many 
  places 
  covered 
  with 
  the 
  massive 
  or 
  gravelly 
  varieties. 
  

  

  Striking 
  examples 
  of 
  the 
  association 
  of 
  the 
  laterite 
  conglomerates 
  

   and 
  gravels 
  may 
  be 
  seen 
  in 
  various 
  places, 
  e. 
  g., 
  

  

  Association 
  of 
  lateri- 
  

   tic 
  conglomerates 
  and 
  on 
  the 
  high 
  ground 
  between 
  Yenkadu 
  and 
  Irum- 
  

  

  gravels. 
  

  

  bedu 
  (Vemgada 
  and 
  Yerrempoor 
  of 
  the 
  Atlas 
  sheet), 
  

   three 
  miles 
  east 
  of 
  Sripermatoor. 
  Here 
  the 
  surface 
  all 
  around 
  Yenkadu 
  

   village 
  is 
  quite 
  purplish 
  in 
  color 
  from 
  the 
  immense 
  quantity 
  of 
  

   ' 
  pisolitic 
  laterite 
  gravel/ 
  which, 
  further 
  to 
  the 
  south-east 
  near 
  Irum- 
  

   bedu, 
  has 
  been 
  cemented 
  together 
  into 
  a 
  hard 
  and 
  almost 
  black 
  lateritic 
  

   conglomerate 
  apparently 
  very 
  rich 
  in 
  iron. 
  The 
  same 
  thing- 
  may 
  also 
  

   be 
  well 
  seen 
  to 
  the 
  south 
  of 
  Puduperu 
  (Poottoorpare 
  of 
  the 
  Atlas 
  

   sheet), 
  where 
  the 
  high 
  ground 
  south 
  of 
  the 
  old 
  high 
  road 
  is 
  capped 
  with 
  

   coarse 
  laterite 
  gravel 
  partially 
  cemented 
  into 
  a 
  hard 
  conglomerate. 
  

  

  It 
  is 
  by 
  no 
  means 
  easy 
  to 
  explain 
  the 
  isolated 
  occurrence 
  of 
  the 
  

   laterite 
  conglomerate 
  spreads 
  scattered 
  over 
  the 
  Madras 
  District. 
  

   Some 
  of 
  the 
  smaller 
  patches, 
  e. 
  g., 
  the 
  small 
  oval 
  patches 
  capping 
  the 
  

   Vellacotta 
  hill 
  and 
  the 
  Munjakaranei 
  hill, 
  must 
  be 
  regarded 
  as 
  

   outliers 
  separated 
  from 
  the 
  main 
  spreads 
  by 
  denuding 
  forces 
  of 
  various 
  

   kinds 
  ; 
  and 
  the 
  outlines 
  of 
  these 
  are 
  invariably 
  sharply 
  denned. 
  But 
  

   many 
  others 
  cannot 
  be 
  ascribed 
  entirely 
  to 
  the 
  denuding 
  effects 
  of 
  

   aqueous 
  or 
  atmospheric 
  agency, 
  but 
  are 
  due 
  to 
  the 
  peculiar 
  distribution 
  of 
  

   the 
  sedimentary 
  materials 
  at 
  the 
  time 
  of 
  the 
  formation 
  of 
  these 
  de- 
  

   posits. 
  It 
  would 
  appear, 
  then, 
  that 
  the 
  marine 
  currents 
  at 
  work 
  in 
  those 
  

   days, 
  deposited 
  in 
  many 
  places 
  great 
  masses 
  of 
  sand 
  of 
  mixed 
  character, 
  

  

  T 
  , 
  ., 
  , 
  •, 
  a 
  great 
  part 
  being 
  pure 
  silicious 
  sand, 
  but 
  a 
  great 
  

  

  Laterite 
  gravels 
  and 
  ox 
  or 
  ' 
  o 
  

  

  conglomerates 
  were 
  pos- 
  fc 
  ] 
  bei 
  ferruginous 
  sand, 
  probably 
  mag- 
  

  

  sibly 
  banks 
  of 
  magnetic 
  r 
  s> 
  & 
  •> 
  i 
  j 
  o 
  

  

  iron 
  sand. 
  netic 
  iron 
  sand, 
  great 
  abundance 
  of 
  which 
  is 
  at 
  

  

  the 
  present 
  time 
  constantly 
  being 
  carried 
  out 
  to 
  sea 
  at 
  every 
  fresh 
  in 
  

   ( 
  S8 
  ) 
  

  

  