﻿68 
  FOOTE 
  : 
  GEOLOGY 
  OF 
  MADRAS. 
  

  

  hundred 
  feet, 
  for 
  they 
  are 
  both 
  over- 
  and 
  . 
  under-laid 
  by 
  other 
  conglo- 
  

   merate 
  beds 
  of 
  equal 
  or 
  greater 
  thickness. 
  The 
  dip 
  is, 
  as 
  nearly 
  as 
  can 
  

   be 
  ascertained 
  on 
  the 
  extremely 
  rugged 
  surfaces, 
  which 
  are 
  only 
  exposed 
  

   for 
  a 
  few 
  square 
  feet, 
  about 
  18°. 
  What 
  may 
  be 
  the 
  nature 
  of 
  the 
  beds 
  

   intermediate 
  between 
  these 
  projecting 
  outcrops 
  of 
  very 
  coarse 
  conglo- 
  

   merate, 
  I 
  cannot 
  pretend 
  to 
  say, 
  so 
  entirely 
  is 
  the 
  true 
  surface 
  obscured 
  by 
  

   the 
  debris 
  of 
  the 
  conglomerates, 
  but 
  I 
  am 
  inclined 
  to 
  think 
  these 
  spaces 
  

   must 
  be 
  occupied 
  by 
  other 
  conglomerates 
  less 
  coarse 
  and 
  cemented 
  by 
  a 
  

   less 
  compact 
  material. 
  

  

  At 
  the 
  head 
  of 
  a 
  smaller 
  ravine 
  opening 
  into 
  the 
  Narnaveram 
  river 
  

   valley 
  about 
  one 
  and 
  a 
  half 
  mile 
  north-west 
  of 
  Sirgulpilly, 
  a 
  fair 
  section 
  of 
  

   one 
  of 
  these 
  immensely 
  coarse 
  conglomerate 
  beds 
  may 
  be 
  seen. 
  The 
  face 
  

   of 
  the 
  section 
  is 
  16 
  or 
  20 
  feet 
  deep, 
  and 
  shows 
  thousands 
  of 
  projecting 
  peb- 
  

   bles, 
  few 
  smaller 
  than 
  a 
  man's 
  fist 
  and 
  many 
  larger 
  than 
  a 
  cocoanut, 
  all 
  

   impacted 
  in 
  a 
  brownish-red 
  ferruginous 
  cement, 
  and 
  apparently 
  without 
  

   any 
  stratification. 
  At 
  the 
  top 
  of 
  the 
  section, 
  which 
  appears 
  to 
  have 
  

   been 
  made 
  in 
  the 
  hope 
  of 
  finding 
  sandstones 
  fit 
  for 
  quarrying, 
  the 
  

   true 
  surface 
  of 
  the 
  bed 
  is 
  exposed 
  for 
  a 
  few 
  square 
  yards, 
  and 
  here 
  the 
  

   cementing 
  material 
  appears 
  spread 
  over 
  the 
  pebbles 
  very 
  smoothly. 
  This 
  

   hard 
  dark 
  chocolate-red 
  matrix 
  has 
  been 
  one 
  source 
  of 
  the 
  ferruginous 
  

   pellets, 
  of 
  which 
  much 
  of 
  the 
  true 
  laterite 
  of 
  the 
  neighbourhood 
  is 
  com- 
  

   posed. 
  The 
  surface 
  of 
  this 
  conglomerate 
  bed 
  shows 
  a 
  dip 
  of 
  10° 
  — 
  12° 
  

   to 
  south-south-east. 
  

  

  The 
  structure 
  of 
  the 
  northern 
  end 
  of 
  the 
  Sattavedu 
  hills 
  was 
  inves- 
  

   tigated 
  by 
  Mr. 
  King, 
  who 
  found 
  them 
  to 
  consist 
  of 
  thick 
  beds 
  of 
  very 
  

   coarse 
  conglomerate 
  with 
  many 
  intercalated 
  beds 
  of 
  sandstone 
  of 
  red 
  

   and 
  reddish-brown 
  color. 
  The 
  beds 
  are 
  exposed 
  in 
  steep 
  cliffs 
  in 
  the 
  

   narrow 
  valleys 
  among 
  the 
  hills, 
  one 
  of 
  which 
  cliffs 
  attains 
  a 
  height 
  of 
  

   150 
  feet. 
  These 
  sandstones 
  proved 
  unfossiliferous, 
  though 
  very 
  carefully 
  

   examined. 
  The 
  shingle 
  enclosed 
  in 
  the 
  conglomerate 
  consists 
  only 
  of 
  

   quartzite. 
  

  

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