﻿76 
  EOOTE 
  : 
  GEOLOGY 
  OF 
  MADRAS. 
  

  

  Excepting 
  the 
  small 
  quarry 
  just 
  described 
  and 
  a 
  very 
  shallow 
  and 
  

   not 
  very 
  satisfactory 
  section 
  in 
  the 
  stream 
  formed 
  by 
  the 
  off-flow 
  of 
  the 
  

   waters 
  of 
  the 
  Alicoor 
  tank, 
  I 
  could 
  find 
  no 
  sections 
  in 
  the 
  whole 
  of 
  the 
  

   series 
  of 
  valleys 
  branching' 
  out 
  of 
  the 
  Alicoor 
  valley. 
  I 
  am 
  quite 
  un- 
  

   able, 
  therefore, 
  to 
  give 
  any 
  satisfactory 
  explanation 
  of 
  the 
  relative 
  posi- 
  

   tions 
  of 
  the 
  two 
  groups 
  of 
  formations. 
  As 
  before 
  stated, 
  there 
  is 
  no 
  

   evidence 
  of 
  any 
  kind 
  opposing 
  the 
  idea 
  that 
  the 
  compact 
  conglomerate 
  

   rested 
  conformably 
  on 
  the 
  uncompacted 
  beds 
  (seen 
  cropping 
  out 
  on 
  the 
  

   western 
  slopes 
  of 
  the 
  water), 
  and 
  have 
  only 
  been 
  removed 
  by 
  extensive 
  

   denudation. 
  

  

  The 
  small 
  amount 
  of 
  evidence 
  furnished 
  by 
  the 
  little 
  section 
  below 
  

  

  the 
  kalingula 
  of 
  the 
  Alicoor 
  tank 
  is 
  favorable 
  

   Alicoor 
  tank 
  section. 
  . 
  . 
  

  

  to 
  this 
  view, 
  the 
  beds 
  exposed 
  being 
  both 
  of 
  them 
  

  

  soft 
  and 
  uncompacted. 
  The 
  two 
  beds 
  here 
  seen 
  are 
  a 
  soft 
  clayey 
  grit, 
  

  

  mottled 
  white 
  and 
  brown, 
  and 
  underlaid 
  by 
  a 
  moderately 
  coarse 
  bed 
  of 
  

  

  uncompacted 
  quartzite 
  shingle 
  conglomerate. 
  The 
  two 
  small 
  sections 
  

  

  here 
  given 
  will 
  help 
  to 
  explain 
  the 
  apparent 
  structure 
  of 
  this 
  group 
  of 
  

  

  hills. 
  Figs. 
  5 
  and 
  6„ 
  

  

  Fig. 
  5.— 
  Ideal 
  section 
  from 
  Chinnareddypolliam 
  to 
  Hodson's 
  Pettah 
  hill. 
  

   o, 
  Gneiss 
  ; 
  b, 
  Runs 
  of 
  quartzite 
  bed 
  ; 
  c, 
  Sripermatoor 
  group 
  ; 
  d, 
  Sattavedu 
  group. 
  

  

  Fig. 
  6.— 
  Section 
  across 
  the 
  Alicoor 
  hills, 
  from 
  north-west 
  by 
  west 
  to 
  south-east 
  by 
  east. 
  

   a, 
  Gneiss; 
  c, 
  Sripermatoor 
  group; 
  d, 
  Sattavedu 
  group 
  ; 
  e, 
  talus. 
  Nos. 
  1—7. 
  Conglomerate 
  beds. 
  

  

  Only 
  one 
  section 
  was 
  met 
  with 
  on 
  the 
  west 
  side 
  of 
  the 
  Alicoor 
  hills 
  

  

  Beds 
  of 
  the 
  Sriperma- 
  nortnward 
  of 
  the 
  Alic 
  °or 
  valley 
  which 
  divides 
  

   toor 
  group. 
  them 
  from 
  the 
  southern 
  part 
  of 
  Naikenpolliam 
  

  

  ( 
  76 
  ) 
  

  

  