﻿90 
  EOOTE 
  : 
  GEOLOGY 
  OF 
  MADRAS 
  

  

  ferruginous, 
  soft 
  clayey 
  sandstone. 
  The 
  beds 
  roll 
  about 
  a 
  g-ood 
  deal, 
  but 
  

  

  at 
  low 
  angles, 
  rarely, 
  if 
  ever, 
  exceeding 
  7° 
  or 
  8°. 
  There 
  are 
  rnany 
  sections 
  

  

  of 
  the 
  shales 
  in 
  the 
  banks 
  of 
  the 
  Kullaur, 
  and 
  on 
  the 
  south 
  side 
  of 
  the 
  

  

  nullah 
  a 
  little 
  south-west 
  of 
  Nungumbaukum, 
  (Nunibaucum 
  of 
  map), 
  the 
  

  

  sliales 
  form 
  a 
  small 
  vertical 
  cliff 
  about 
  12 
  feet 
  high, 
  capped 
  by 
  4 
  feet 
  of 
  

  

  laterite 
  gravel. 
  Further 
  down 
  the 
  nullah 
  about 
  half 
  a 
  mile 
  from 
  the 
  

  

  Corteliar, 
  the 
  southern 
  bank 
  of 
  the 
  Kullaur 
  shows 
  a 
  small 
  scarp 
  of 
  shales, 
  

  

  „ 
  . 
  , 
  , 
  , 
  . 
  in 
  the 
  base 
  of 
  which 
  mav 
  be 
  seen 
  numerous 
  large 
  

   Conglomerate 
  bed 
  in 
  J 
  ° 
  

  

  the 
  shales 
  near 
  Punch. 
  au( 
  j 
  sma 
  \\ 
  pebbles 
  of 
  quartzite 
  and 
  weathered 
  trap. 
  

   The 
  trap 
  is 
  identical 
  in 
  appearance 
  with 
  that 
  found 
  by 
  Mr. 
  King 
  in 
  

   dykes 
  in 
  rocks 
  of 
  the 
  Kaddapa 
  series 
  north 
  of 
  Nagloperam. 
  This 
  is 
  

   the 
  only 
  case 
  in 
  which 
  these 
  shales 
  were 
  observed 
  to 
  include 
  anything 
  

   larger 
  than 
  grains 
  of 
  grit 
  or 
  a 
  few 
  small 
  gritty 
  laminse. 
  

  

  The 
  banks 
  of 
  the 
  Attrampakkam 
  nullah 
  offer 
  very 
  similar 
  sections, 
  

  

  . 
  . 
  which 
  show 
  the 
  rolling 
  about 
  of 
  the 
  shales, 
  and 
  

  

  Attrampakkam 
  see- 
  ° 
  ' 
  

  

  tl0US 
  - 
  also 
  the 
  great 
  erosion 
  which 
  the 
  surface 
  of 
  the 
  

  

  formation 
  underwent, 
  before 
  the 
  deposition 
  of 
  the 
  laterite. 
  

  

  The 
  hollows 
  formed 
  by 
  that 
  erosion 
  are 
  now 
  filled 
  with 
  lateritic 
  

   shingle 
  conglomerate 
  containing 
  numerous 
  stone 
  implements. 
  

  

  The 
  upper 
  part 
  of 
  the 
  shales 
  is 
  freeer 
  from 
  ferruginous 
  sandy 
  part- 
  

   ings, 
  and, 
  as 
  a 
  rule, 
  also 
  from 
  iron- 
  stains, 
  excepting 
  of 
  course 
  from 
  such 
  

   as 
  proceed 
  from 
  infiltration 
  of 
  ferriferous 
  water 
  from 
  the 
  overlying 
  laterite. 
  

   The 
  shale 
  beds 
  here 
  proved 
  but 
  very 
  sparingly 
  fossiliferous. 
  In 
  one 
  of 
  

   the 
  reddish-brown 
  friable 
  sandstone 
  layers 
  occurring 
  in 
  the 
  shales 
  about 
  

   half 
  a 
  mile 
  north-west 
  of 
  Attrampakkam 
  village, 
  the 
  cast 
  of 
  a 
  small 
  

   shell, 
  resembling 
  a 
  Lucina, 
  was 
  found 
  with 
  a 
  few 
  obscure 
  impressions 
  of 
  

   plants. 
  These 
  were 
  the 
  only 
  organic 
  remains 
  found 
  in 
  the 
  Attrampakkam 
  

   millah 
  sections. 
  The 
  shales 
  in 
  the 
  Kullaur 
  yielded 
  only 
  a 
  fragment 
  of 
  

   an 
  Ammonite 
  with 
  some 
  obscure 
  and 
  indeterminable 
  plant 
  remains, 
  found 
  

   at 
  Nungumbaukum. 
  

  

  I 
  «JU 
  ) 
  

  

  