﻿62 
  FOOTE 
  : 
  GEOLOGY 
  OF 
  MADRAS. 
  

  

  lateritic 
  gravel, 
  in 
  which 
  some 
  smaller 
  lumps 
  occupy 
  a 
  higher 
  level, 
  

   some 
  3^ 
  to 
  4 
  feet 
  ahove 
  the 
  surface 
  of 
  the 
  grit 
  bed 
  No. 
  4. 
  In 
  color 
  

   these 
  blocks 
  are 
  grey 
  or 
  greenish-grey, 
  and 
  they 
  are 
  formed 
  of 
  gritty 
  

   detritus 
  of 
  granitic 
  rocks 
  ; 
  in 
  this 
  respect 
  and 
  to 
  some 
  extent 
  in 
  color 
  

   they 
  resemble 
  the 
  underlying 
  Rajmahal 
  grit 
  bed. 
  The 
  grit 
  is 
  con- 
  

   siderably 
  indurated. 
  The 
  number 
  of 
  blocks 
  is 
  not 
  large, 
  and 
  some 
  

   have 
  been 
  built 
  into 
  a 
  retaining 
  wall 
  to 
  a 
  waste-weir 
  for 
  the 
  

   channel. 
  Of 
  those 
  exposed 
  in 
  the 
  section, 
  some 
  eight 
  or 
  ten 
  only 
  in 
  

   number, 
  I 
  broke 
  up 
  all 
  but 
  two 
  or 
  three 
  in 
  search 
  of 
  fossils, 
  of 
  which 
  

   a 
  considerable 
  number 
  was 
  obtained. 
  The 
  fossils 
  were 
  Ammonites 
  (four 
  

   or 
  five 
  species) 
  , 
  Belemnites, 
  Nautilus 
  ? 
  Pleurotomaria, 
  two 
  or 
  three 
  

   species, 
  &c. 
  No 
  similar 
  blocks 
  were 
  seen 
  anywhere 
  else. 
  They 
  are 
  true 
  

   water-borne 
  boulders 
  (the 
  largest 
  measuring 
  less 
  than 
  half 
  a 
  cubic 
  yard 
  

   in 
  its 
  solid 
  contents), 
  but 
  whence 
  they 
  come 
  could 
  not 
  be 
  ascertained; 
  

   nothing 
  resembling 
  them 
  was 
  to 
  be 
  found 
  on 
  the 
  higher 
  grounds 
  to 
  the 
  

   west 
  and 
  north, 
  though 
  specially 
  searched. 
  Probably 
  these 
  grit 
  boulders 
  

   were 
  derived 
  from 
  some 
  formation 
  which 
  was 
  all 
  but 
  entirely 
  removed 
  

   by 
  denudation 
  prior 
  to 
  the 
  commencement 
  of 
  the 
  lateritic 
  period. 
  

  

  Other 
  boulders 
  of 
  gneissic 
  rocks 
  of, 
  in 
  some 
  cases, 
  larger 
  size 
  occur 
  

   in 
  the 
  lateritic 
  gravel 
  of 
  this 
  place. 
  

  

  ( 
  62 
  ) 
  

  

  