﻿86 
  FOOTE 
  : 
  GEOLOGY 
  OF 
  MADRAS. 
  

  

  When 
  visited 
  by 
  me 
  in 
  1864, 
  and 
  again 
  in 
  1865, 
  the 
  wells, 
  which 
  

   afford 
  the 
  only 
  sections 
  existing 
  there, 
  were 
  full 
  to 
  overflowing 
  after 
  the 
  

   south-west 
  monsoon. 
  The 
  material 
  turned 
  out 
  of 
  those 
  near 
  Woter- 
  

   polliam 
  was 
  coarse 
  quartzite 
  shingle, 
  with 
  pale-drab 
  sandy 
  grit. 
  Near 
  

   the 
  south 
  end 
  of 
  the 
  valley, 
  close 
  to 
  the 
  Connicoma 
  tank, 
  pale-buff 
  sand 
  

   had 
  been 
  thrown 
  out 
  of 
  a 
  small 
  newly 
  sunk 
  well. 
  

  

  In 
  the 
  next 
  or 
  central 
  valley, 
  several 
  sections 
  were 
  met 
  with 
  in 
  the 
  

   banks 
  of 
  the 
  large 
  nullah 
  which 
  feeds 
  the 
  Con- 
  

  

  Conjibuddy 
  section. 
  

  

  jibuddy 
  tank, 
  and 
  in 
  the 
  dry 
  season 
  many 
  of 
  the 
  

   wells 
  would 
  probably 
  give 
  good 
  sections, 
  as 
  they 
  are 
  deep 
  and 
  not 
  walled 
  

   up. 
  The 
  most 
  southerly 
  of 
  these 
  sections 
  occurs 
  at 
  Conjibuddy 
  at 
  the 
  

   west 
  end 
  of 
  the 
  tank 
  bund, 
  which 
  was 
  breached 
  some 
  years 
  age, 
  and 
  the 
  

   ground 
  below 
  the 
  breach 
  excavated 
  by 
  the 
  escaping 
  waters 
  to 
  a 
  depth 
  

   of 
  from 
  12 
  to 
  15 
  feet. 
  The 
  lowest 
  rocks 
  seen 
  here 
  are 
  coarse 
  pebbly 
  

   sandstones 
  rather 
  friable 
  ; 
  these 
  are 
  seen 
  only 
  in 
  the 
  bed 
  of 
  the 
  channel, 
  

   and 
  not 
  more 
  than 
  one 
  foot 
  and 
  a 
  half 
  in 
  thickness 
  of 
  the 
  beds 
  

   is 
  exposed. 
  

  

  The 
  included 
  pebbles 
  consist 
  of 
  granitic 
  rocks, 
  quartzite, 
  and 
  occa- 
  

   sionally 
  of 
  blackish, 
  dark-grey 
  and 
  purplish 
  clay-slate. 
  The 
  matrix 
  is 
  

   drab-grey 
  or 
  greenish-grey 
  in 
  colour. 
  The 
  sandstones 
  dip 
  15°-20° 
  

   east-south-east. 
  Resting 
  on 
  these 
  pebbly 
  sandstones 
  is 
  a 
  very 
  coarse 
  

   boulder 
  bed 
  containing 
  very 
  large 
  rounded 
  masses 
  of 
  decomposing 
  syenite, 
  

   and 
  also 
  of 
  quartzite 
  with 
  occasional 
  smaller 
  fragments 
  of 
  slate. 
  Of 
  the 
  

   two 
  former, 
  many 
  of 
  the 
  boulders 
  must 
  weigh 
  from 
  2 
  to 
  3 
  and 
  4 
  cwt., 
  

   with 
  others 
  diminishing 
  from 
  that 
  size 
  down 
  to 
  mere 
  pebbles. 
  The 
  

   largest 
  piece 
  of 
  clay-slate 
  observed 
  weighed 
  about 
  7 
  or 
  8 
  lbs., 
  and 
  was 
  of 
  

   purple 
  color. 
  On 
  the 
  top 
  of 
  the 
  boulder-bed, 
  which 
  is 
  from 
  4 
  to 
  5 
  feet 
  

   thick, 
  lies 
  a 
  bed 
  of 
  rubble, 
  apparently 
  the 
  reconstructed 
  surface 
  of 
  the 
  

   boulder 
  bed, 
  which 
  has 
  a 
  thickness 
  of 
  about 
  a 
  yard, 
  and 
  is 
  in 
  its 
  turn 
  

   covered 
  by 
  about 
  3 
  feet 
  of 
  debris 
  of 
  shingly 
  laterite. 
  

  

  ( 
  86 
  ) 
  

  

  