﻿JURASSIC 
  ROCKS 
  ! 
  AIJCOOR 
  ARE4. 
  81 
  

  

  There 
  is 
  much 
  less 
  difficulty 
  in 
  supposing 
  that 
  these 
  blocks 
  are 
  

   really 
  the 
  remains 
  of 
  a 
  thin 
  bed 
  of 
  quartzite, 
  partially 
  bioken 
  up 
  by 
  the 
  

   destruction 
  of 
  the 
  underlying 
  much 
  softer 
  gneissic 
  rockt; 
  the 
  larger 
  

   masses 
  being 
  left 
  nearly 
  in 
  their 
  original 
  position, 
  or 
  shifted 
  only 
  to 
  

   little 
  distances, 
  and 
  that 
  the 
  other 
  materials 
  of 
  the 
  conglomerate, 
  which 
  

   appear 
  to 
  include 
  them, 
  were 
  heaped 
  over 
  and 
  around 
  them 
  it 
  some 
  

   subsequent 
  period 
  of 
  subsidence. 
  

  

  With 
  reference 
  to 
  this, 
  some 
  importance 
  seems 
  to 
  attach 
  to 
  'he 
  

   fact 
  that 
  blocks 
  of 
  gneissic 
  rocks 
  of 
  great 
  size 
  only 
  begin 
  to 
  be 
  include! 
  

   in 
  the 
  Rajmahal 
  conglomerates 
  to 
  the 
  southward 
  of 
  the 
  country 
  where 
  

   these 
  great 
  quartzite 
  masses 
  are 
  met 
  with. 
  

  

  If 
  these 
  blocks 
  be 
  considered 
  as 
  the 
  ruins 
  in 
  situ 
  of 
  a 
  bed 
  of 
  quart- 
  

   zite, 
  it 
  is 
  the 
  most 
  southerly 
  extension 
  of 
  the 
  Kaddapa 
  series 
  known. 
  

  

  Many 
  examples 
  of 
  the 
  inclusion 
  of 
  great 
  blocks 
  and 
  boulders 
  of 
  

   gneiss 
  in 
  the 
  conglomerate 
  beds 
  of 
  the 
  same 
  age 
  underlying 
  the 
  cretace- 
  

   ous 
  rocks 
  in 
  Trichinopoly 
  district, 
  are 
  cited 
  in 
  Mr. 
  H. 
  R 
  Blanford's 
  

   report 
  on 
  the 
  Cretaceous 
  rocks 
  (Memoirs, 
  Geological 
  Survey 
  of 
  India, 
  

   vol. 
  IV, 
  pp. 
  40 
  and 
  47). 
  

  

  Overlying 
  these 
  blocks, 
  which 
  apparently 
  represent 
  the 
  base 
  of 
  the 
  

  

  lower 
  group 
  of 
  the 
  Bajmahal 
  rocks, 
  is 
  a 
  series 
  of 
  

   Higher 
  beds. 
  . 
  

  

  very 
  coarse 
  conglomerates 
  with 
  intercalated 
  friable 
  

  

  sandstones 
  and 
  clayey 
  grits, 
  and 
  higher 
  up 
  in 
  the 
  series 
  sandy 
  shales 
  

  

  also 
  appear 
  in 
  thin 
  layers. 
  The 
  whole 
  series 
  is 
  by 
  no 
  means 
  known, 
  

  

  owing 
  to 
  the 
  paucity 
  of 
  sections 
  penetrating 
  the 
  thick 
  layer 
  of 
  debris 
  

  

  which 
  everywhere 
  covers 
  the 
  surface 
  of 
  the 
  hills 
  to 
  a 
  depth 
  very 
  often 
  

  

  of 
  two 
  or 
  three 
  yards 
  or 
  more* 
  

  

  Only 
  four 
  sections 
  were 
  seen 
  along 
  the 
  southern 
  slopes 
  of 
  the 
  

  

  „ 
  ., 
  u 
  - 
  _ 
  Naikenpolliam 
  ridge 
  from 
  east 
  of 
  Panoor 
  to 
  the 
  

  

  tion 
  ' 
  most 
  southerly 
  extremity 
  close 
  to 
  Chinnareddy- 
  

  

  polliam, 
  in 
  which 
  the 
  debris 
  was 
  penetrated. 
  The 
  first 
  of 
  these 
  occurs 
  at 
  

   l 
  ( 
  81 
  ) 
  

  

  