﻿60 
  POOTE 
  : 
  GEOLOGY 
  OF 
  MADRAS. 
  

  

  The 
  same 
  succession 
  of 
  beds 
  is 
  displayed, 
  but 
  less 
  clearly, 
  in 
  the 
  

  

  small 
  outlying 
  hill 
  at 
  Manjakaranei, 
  with 
  this 
  

  

  Manjakaranei 
  section. 
  ^^ 
  ^ 
  ^ 
  capping 
  bed 
  of 
  y^fa 
  appears 
  

  

  to 
  pass 
  down 
  gradually 
  into 
  vermicularly 
  cellular 
  clayey 
  grits, 
  with 
  a 
  

   few 
  lateritic 
  lumps. 
  These 
  grits 
  again 
  appear 
  to 
  graduate 
  into 
  the 
  

   coarse, 
  mottled, 
  friable 
  grits, 
  which 
  themselves 
  become 
  purer 
  and 
  whiter 
  

   the 
  deeper 
  they 
  go. 
  This 
  outlier 
  forms 
  a 
  small 
  island 
  in 
  the 
  alluvium 
  

   of 
  the 
  Corteliar 
  and 
  Narnaveram 
  river 
  delta. 
  The 
  height 
  of 
  this 
  hill 
  is 
  

   about 
  50 
  feet 
  above 
  the 
  surrounding 
  fields. 
  The 
  thickness 
  of 
  the 
  true 
  

   laterite 
  is 
  about 
  4 
  or 
  5 
  feet 
  at 
  the 
  utmost. 
  

  

  Whether 
  the 
  vermicularly 
  cellular 
  clayey 
  grits 
  into 
  which 
  the 
  

   laterite 
  apparently 
  passes 
  really 
  belong 
  to 
  the 
  laterite 
  series 
  or 
  to 
  the 
  

   Cuddalore 
  series 
  has 
  yet 
  to 
  be 
  decided. 
  In 
  this 
  section 
  the 
  laterite 
  

   appears 
  to 
  belong 
  to 
  the 
  Cuddalore 
  series, 
  and 
  so 
  also 
  does 
  the 
  laterite 
  on 
  

   top 
  of 
  the 
  line 
  of 
  cliffs 
  along 
  thti 
  Corteliar, 
  but 
  in 
  the 
  Yerumeivetti- 
  

   paleiyam 
  section 
  there 
  is 
  no 
  apparent 
  downward 
  passage 
  into 
  the 
  mottled 
  

   grits. 
  As 
  in 
  the 
  case 
  of 
  the 
  Tanjore 
  area 
  of 
  Cuddalore 
  rocks, 
  (*) 
  

   the 
  want 
  of 
  conformity 
  between 
  them 
  and 
  the 
  capping 
  bed 
  of 
  laterite 
  

   is 
  more 
  apparent 
  in 
  the 
  great 
  breadth 
  of 
  the 
  overlap, 
  or 
  westward 
  

   extension 
  of 
  the 
  laterite 
  over 
  the 
  adjacent 
  gneiss 
  region, 
  than 
  by 
  a 
  

   positive 
  and 
  distinct 
  discrepancy 
  in 
  the 
  position 
  of 
  the 
  respective 
  strata 
  

   visible 
  in 
  any 
  particular 
  section 
  ; 
  so 
  in 
  the 
  case 
  of 
  the 
  laterite 
  and 
  Cudda- 
  

   lore 
  series, 
  in 
  the 
  part 
  of 
  the 
  Madras 
  district 
  just 
  described, 
  does 
  

   the 
  wide 
  extension 
  of 
  the 
  laterite 
  on 
  all 
  sides 
  far 
  beyond 
  the 
  utmost 
  

   extent 
  of 
  the 
  Cuddalore 
  rocks 
  prove 
  the 
  existence 
  of 
  an 
  overlap 
  and 
  

   of 
  a 
  real 
  unconformity. 
  

  

  (*) 
  See 
  Memoirs, 
  Geological 
  Survey 
  of 
  India, 
  Vol. 
  IV, 
  Part 
  2, 
  p. 
  42. 
  

  

  ( 
  CO 
  ) 
  

  

  