﻿92 
  FOOTE 
  : 
  GEOLOGY 
  OF 
  MADRAS. 
  

  

  Following 
  the 
  boundary 
  which 
  now 
  trends 
  north-westward, 
  a 
  small 
  

   section 
  (in 
  a 
  newly 
  excavated 
  well) 
  may 
  be 
  found 
  

   1 
  y 
  beside 
  a 
  group 
  of 
  trees 
  standing 
  on 
  the 
  rising 
  

  

  a-round 
  south 
  of 
  Pilyur 
  (Pilwoor 
  of 
  map). 
  Buff-colored 
  friable 
  sand- 
  

   stone, 
  with 
  small 
  ferruginous 
  concretions, 
  is 
  here 
  exposed 
  below 
  the 
  

   lateritic 
  gravels. 
  The 
  lithological 
  characters 
  of 
  this 
  sandstone 
  are 
  not 
  

   characteristic 
  enough 
  to 
  pronounce 
  it 
  decidedly 
  to 
  belong 
  to 
  the 
  Raj- 
  

   mahal 
  system 
  in 
  the 
  absence 
  of 
  fossils, 
  but 
  it 
  has 
  more 
  similarity 
  

   to 
  many 
  of 
  the 
  friable 
  sandstones 
  just 
  described 
  of 
  unquestionable 
  

   Rajmahal 
  age 
  than 
  to 
  the 
  gritty 
  sandstones 
  of 
  the 
  Cuddalore 
  series. 
  

   Of 
  similarly 
  doubtful 
  character 
  is 
  the 
  gritty 
  friable 
  sandstone 
  of 
  greyish- 
  

   white 
  color 
  with 
  slight 
  traces 
  of 
  shale 
  which 
  has 
  been 
  thrown 
  up 
  during 
  

   the 
  building 
  of 
  the 
  village 
  tank 
  of 
  Tirumullavayal 
  

   n-uirni 
  avaya 
  . 
  (Trimullavoil 
  of 
  map) 
  about 
  one 
  mile 
  and 
  three 
  

  

  quarters 
  north-east 
  of 
  Avadi 
  railway 
  station. 
  Here 
  the 
  general 
  appea- 
  

   rance 
  of 
  the 
  rock, 
  the 
  shales 
  excepted, 
  is 
  more 
  like 
  the 
  grit 
  beds 
  of 
  

   the 
  Cuddalore 
  series, 
  e. 
  g., 
  in 
  the 
  cliffs 
  along 
  the 
  Corteliar 
  at 
  Yermootapol- 
  

   liam. 
  The 
  real 
  affinity 
  can 
  only 
  be 
  settled 
  by 
  the 
  discovery 
  of 
  fossils 
  of 
  

   distinctive 
  character. 
  Similar 
  buff 
  shaly 
  sandstones 
  and 
  grits 
  show 
  at 
  

   various 
  points 
  along 
  the 
  railway 
  cuttings 
  near 
  Avadi 
  station, 
  but 
  only 
  

   to 
  a 
  very 
  small 
  extent 
  because 
  of 
  the 
  turfing 
  of 
  the 
  slopes. 
  In 
  litholo- 
  

   o-ical 
  character 
  they 
  bear 
  strong 
  resemblance 
  to 
  certain 
  sandstones 
  and 
  

   shales 
  occurring 
  at 
  Coopoor 
  a 
  few 
  miles 
  to 
  the 
  south-west, 
  which 
  will 
  

   be 
  described 
  further 
  on. 
  

  

  (c.) 
  — 
  The 
  Pganoor 
  area. 
  

  

  The 
  shape 
  of 
  this 
  area, 
  which 
  lies 
  south 
  of 
  the 
  Naggery 
  river, 
  is 
  

   extremely 
  irregular, 
  because 
  the 
  greater 
  part 
  of 
  the 
  surface 
  is 
  obscured 
  

   by 
  a 
  continuous 
  bed 
  of 
  shingly 
  laterite 
  conglomerate, 
  which 
  only 
  leaves 
  

   exposed 
  a 
  narrow 
  belt 
  of 
  Rajmahal 
  rocks 
  skirting 
  along 
  the 
  alluvium 
  

   of 
  the 
  Naggery 
  and 
  Corteliar 
  valley. 
  West 
  and 
  south-west 
  of 
  Pyanoor 
  

   this 
  belt 
  widens 
  considerably. 
  

  

  ( 
  02 
  ) 
  

  

  