﻿JURASSIC 
  ROCKS: 
  SRIPERMATOdR 
  AREA. 
  121 
  

  

  the 
  appearance 
  of 
  the 
  sandstones 
  is, 
  however, 
  so 
  characteristic 
  that 
  it 
  

   is 
  impossible 
  to 
  doubt 
  that 
  they 
  belong 
  to 
  the 
  Rajmahal 
  series 
  and 
  form 
  

   the 
  most 
  westerly 
  out-crop 
  of 
  it, 
  known 
  to 
  the 
  north 
  of 
  the 
  Palar 
  river. 
  

   In 
  this 
  case, 
  as 
  in 
  that 
  of 
  the 
  Cotrumbaueum 
  section 
  described 
  at 
  

   page 
  119, 
  there 
  was 
  no 
  appearance 
  of 
  the 
  Rajmahal 
  rocks 
  at 
  the 
  surface 
  ; 
  

   they 
  are, 
  therefore, 
  not 
  shown 
  on 
  the 
  map. 
  

  

  It 
  is 
  not 
  possible 
  to 
  arrive 
  at 
  any 
  conclusion 
  about 
  the 
  relations 
  of 
  

   these 
  southern 
  Rajmahal 
  rocks 
  to 
  those 
  occurring 
  in 
  Behar 
  and 
  Cutch, 
  

   till 
  the 
  comparison 
  of 
  the 
  fossil 
  floras 
  and 
  faunas 
  of 
  the 
  several 
  regions 
  

   shall 
  have 
  been 
  completed 
  and 
  published. 
  

  

  The 
  nature 
  of 
  the 
  rocks 
  in 
  the 
  Trichinopoly 
  region 
  in 
  a 
  lithological 
  

   point 
  of 
  view 
  accords 
  very 
  clearly, 
  especially 
  in 
  the 
  nature 
  of 
  the 
  boulder- 
  

   beds 
  and 
  the 
  generally 
  arenaceous 
  character 
  of 
  the 
  micaceous 
  shales. 
  The 
  

   differences 
  are 
  only 
  what 
  might 
  have 
  been 
  expected 
  from 
  the 
  differences 
  

   of 
  the 
  gneiss 
  rocks 
  in 
  the 
  two 
  districts. 
  In 
  the 
  Madras 
  and 
  North 
  Arcot 
  

   districts 
  the 
  quantity 
  and 
  purity 
  of 
  the 
  clay 
  beds 
  is, 
  on 
  the 
  whole, 
  very 
  

   remarkable, 
  but 
  is 
  the 
  natural 
  result 
  of 
  the 
  degradation 
  of 
  the 
  very 
  

   coarse 
  granitoid 
  gneiss 
  which 
  occurs 
  so 
  largely 
  in 
  the 
  country 
  north 
  and 
  

   west 
  of 
  the 
  Palar 
  and 
  Poiney 
  rivers, 
  both 
  in 
  the 
  low 
  country 
  and 
  

   forming 
  the 
  eastern 
  edge 
  of 
  the 
  Palamaner 
  table 
  land 
  and 
  the 
  mountain 
  

   spurs 
  descending 
  from 
  it. 
  This 
  coarse 
  granitoid 
  gneiss 
  contains, 
  as 
  a 
  

   rule, 
  a 
  very 
  large 
  proportion 
  of 
  felspar 
  of 
  more 
  than 
  one 
  variety, 
  which 
  

   by 
  decomposition 
  would 
  yield 
  infinitely 
  greater 
  supplies 
  of 
  pure 
  argilla- 
  

   ceous 
  matter 
  than 
  would 
  the. 
  far 
  more 
  highly 
  silicious 
  and 
  hornblendic 
  

   gneiss 
  of 
  the 
  Trichinopoly 
  and 
  Salem 
  mountain 
  regions. 
  

  

  There 
  is 
  a 
  very 
  marked 
  resemblance 
  between 
  the 
  Rajmahal 
  beds 
  

   occurring 
  in 
  the 
  Nellore 
  district 
  to 
  the 
  west 
  of 
  Ramiapatnam 
  and 
  those 
  

   described 
  as 
  occurring 
  in 
  the 
  southern 
  part 
  of 
  the 
  Alicoor 
  area 
  and 
  in 
  

   the 
  Pyanoor 
  area. 
  Micaceous 
  sandstone 
  and 
  shales 
  with 
  a 
  few 
  beds 
  of 
  

   gritty 
  sandstone 
  predominate 
  in 
  both 
  quarters, 
  and 
  are 
  remarkably 
  

   alike 
  both 
  in 
  color 
  and 
  texture. 
  They 
  agree 
  also 
  in 
  containing 
  very 
  

   Q 
  ( 
  121 
  ) 
  

  

  