﻿74 
  FOOTE 
  : 
  GEOLOGY 
  OF 
  MADRAS. 
  

  

  exposed 
  in 
  a 
  very 
  fine 
  cliff,, 
  at 
  the 
  head 
  of 
  a 
  large 
  ravine 
  opening 
  east- 
  

   ward, 
  to 
  a 
  depth 
  of 
  fully 
  100 
  feet. 
  The 
  head 
  of 
  this 
  ravine 
  is 
  very 
  

   remarkable, 
  as 
  presenting 
  unmistakeable 
  evidence 
  of 
  having 
  been 
  exca- 
  

   vated 
  by 
  marine 
  action. 
  

  

  The 
  conglomerate 
  bed 
  has 
  been 
  eaten 
  into 
  by 
  surf 
  action 
  so 
  much 
  

   that 
  a 
  perfect 
  amphitheatre 
  200 
  — 
  300 
  yards 
  across 
  

   and 
  of 
  about 
  the 
  same 
  depth 
  has 
  been 
  formed, 
  

   surrounded 
  by 
  truly 
  vertical 
  cliffs. 
  These 
  cliffs 
  are 
  highest 
  at 
  the 
  apex 
  

   of 
  the 
  curve, 
  the 
  dip 
  of 
  the 
  bed 
  being 
  down 
  the 
  valley 
  (eastward) 
  . 
  On 
  

   the 
  south 
  of 
  the 
  amphitheatre 
  a 
  cave 
  of 
  some 
  magnitude 
  has 
  been 
  formed 
  

   by 
  the 
  undermining 
  of 
  the 
  cliff. 
  The 
  shape 
  of 
  the 
  cave 
  in 
  plan 
  is 
  that 
  

   of 
  a 
  shallow 
  crescent, 
  the 
  chord 
  of 
  the 
  arc 
  measuring 
  about 
  230 
  feet 
  

   and 
  the 
  greatest 
  depth 
  being 
  about 
  65 
  feet. 
  

  

  The 
  greatest 
  height 
  of 
  the 
  arched 
  opening 
  cannot 
  be 
  much 
  under 
  

   30 
  feet, 
  which 
  decreases 
  to 
  4 
  or 
  5 
  feet 
  at 
  the 
  back 
  of 
  the 
  cave, 
  the 
  floor 
  

   rising 
  also 
  in 
  the 
  same 
  direction. 
  

  

  Both 
  floor 
  and 
  roof 
  consist 
  of 
  the 
  conglomerate, 
  and 
  are 
  not 
  

   covered 
  by 
  any 
  incrustation. 
  At 
  the 
  back 
  of 
  the 
  cave 
  is 
  a 
  perfectly 
  

   loose 
  accumulation 
  of 
  grey 
  calcareous 
  dust, 
  1 
  or 
  2 
  feet 
  thick, 
  con- 
  

   sisting 
  apparently 
  of 
  decomposed 
  bat's 
  dung 
  and 
  ashes. 
  It 
  contains 
  

   nothing 
  but 
  some 
  dead 
  snail 
  shells 
  of 
  the 
  species 
  common 
  in 
  the 
  

   neighbourhood. 
  A 
  small 
  quantity 
  of 
  deliciously 
  clear 
  and 
  cool 
  water 
  

   drips 
  from 
  the 
  roof 
  at 
  the 
  west 
  end, 
  and 
  is 
  collected 
  in 
  chatties 
  by 
  the 
  

   goat 
  herds 
  frequenting 
  the 
  valley. 
  The 
  waters 
  of 
  the 
  small 
  stream 
  

   falling 
  over 
  the 
  cliffs 
  just 
  above 
  the 
  cave, 
  when 
  in 
  flood, 
  must 
  scour 
  the 
  

   greater 
  part 
  of 
  the 
  floor, 
  and 
  this 
  alone 
  is 
  sufficient 
  to 
  account 
  for 
  the 
  

   absence 
  of 
  any 
  accumulation 
  of 
  soil, 
  &c, 
  in 
  the 
  cave, 
  but 
  the 
  stream 
  

   drains 
  too 
  small 
  an 
  area 
  ever 
  to 
  have 
  been 
  large 
  enough 
  to 
  have 
  had 
  

   much 
  influence, 
  if 
  any, 
  in 
  enlarging 
  the 
  cave. 
  

  

  Another 
  similar 
  but 
  much 
  smaller 
  cave 
  occurs 
  in 
  the 
  next 
  overlying 
  

   conglomerate 
  bed 
  a 
  few 
  hundred 
  yards 
  further 
  down 
  the 
  ravine. 
  

   ( 
  71 
  ) 
  

  

  