﻿UPPER 
  CRETACEOUS 
  SERIES. 
  (lGNEOUS.) 
  59 
  

  

  able 
  igneous 
  intrusions. 
  One 
  of 
  these 
  forms 
  a 
  ridge 
  broken 
  at 
  Jolwat 
  evi- 
  

   dently 
  by 
  denudation. 
  It 
  is 
  capped 
  by 
  masses 
  of 
  a 
  peculiarly 
  altered, 
  brown- 
  

   ish 
  calcareous 
  rock, 
  so 
  often 
  alluded 
  to 
  in 
  the 
  preceding 
  pages, 
  1 
  and 
  termi- 
  

   nates 
  at 
  Kulwat 
  by 
  the 
  Hatni 
  in 
  a 
  tract 
  of 
  altered 
  infra-trappeans 
  simi- 
  

   lar 
  to 
  that 
  from 
  which 
  it 
  originates. 
  The 
  altered 
  rock 
  is 
  harder 
  than 
  the 
  

   trap, 
  so 
  that 
  it 
  stands 
  meteoric 
  degradation 
  better 
  than 
  the 
  latter, 
  and 
  

   forms 
  the 
  peaks 
  and 
  summits 
  of 
  trap 
  hills. 
  This 
  circumstance, 
  as 
  well 
  

   as 
  its 
  colour, 
  led 
  me 
  at 
  one 
  time 
  to 
  confound 
  it 
  with 
  the 
  Barwani 
  f 
  el 
  stone. 
  

   But 
  the 
  former 
  is 
  markedly 
  calcareous, 
  whereas 
  the 
  latter 
  is 
  not 
  so, 
  ex- 
  

   cept 
  on 
  the 
  weathered 
  surface 
  ; 
  besides, 
  felspar 
  crystals 
  are 
  abundant 
  in 
  

   the 
  one, 
  but 
  quite 
  absent 
  in 
  the 
  other. 
  There 
  are 
  other 
  points 
  of 
  differ- 
  

   ence, 
  as 
  will 
  be 
  presently 
  seen. 
  The 
  rock 
  in 
  question 
  is 
  so 
  common 
  in 
  

   the 
  trap 
  country 
  west 
  of 
  the 
  Hatni, 
  south 
  of 
  the 
  metamorphic 
  and 
  cre- 
  

   taceous 
  tracts, 
  that 
  it 
  demands 
  a 
  few 
  lines 
  of 
  detailed 
  notice. 
  

   The 
  following 
  characters 
  may 
  be 
  tabulated 
  : 
  — 
  

  

  1. 
  It 
  is 
  usually 
  found 
  in 
  unbedded 
  masses 
  at 
  the 
  top 
  of 
  trap 
  hills 
  

  

  and 
  ridges. 
  

  

  2. 
  These 
  ridges 
  are 
  of 
  a 
  rather 
  compact 
  and 
  fine-grained 
  but 
  crys- 
  

  

  talline 
  rock 
  (dolerite) 
  forming 
  in 
  several 
  cases 
  the 
  lateral 
  por- 
  

   tion 
  of 
  dykes 
  with 
  markedly 
  crystalline 
  rock 
  structure 
  at 
  the 
  

   centre. 
  

  

  3. 
  The 
  ridges 
  run 
  in 
  a 
  line 
  generally 
  in 
  an 
  east- 
  western 
  direction. 
  

  

  4. 
  The 
  rock 
  under 
  notice 
  is 
  at 
  places 
  associated 
  with 
  highly 
  altered 
  

  

  and 
  intensely 
  hardened 
  shaly 
  and 
  silicious 
  rocks. 
  

   But 
  the 
  most 
  marked 
  peculiarity 
  of 
  the 
  rock, 
  and 
  that 
  which 
  above 
  all 
  

   renders 
  its 
  lithology 
  most 
  puzzling, 
  is 
  the 
  presence 
  in 
  it 
  at 
  places 
  of 
  nests 
  

   and 
  patches 
  of 
  a 
  trappean-looking 
  substance, 
  the 
  igneous 
  origin 
  of 
  which 
  

   is 
  manifest 
  under 
  the 
  microscope. 
  Considering, 
  as 
  I 
  did 
  at 
  starting, 
  the 
  

   strange 
  rock 
  as 
  inter-trappean, 
  owing 
  to 
  its 
  invariable 
  superposition 
  on 
  

   the 
  trap, 
  I 
  accounted 
  for 
  the 
  presence 
  of 
  the 
  volcanic 
  matter 
  in 
  it 
  by 
  

   the 
  showering 
  of 
  the 
  former 
  into 
  the 
  lake 
  or 
  sea, 
  in 
  which 
  streams 
  were 
  

   depositing 
  calcareous 
  sediment 
  in 
  inter-trappean 
  times 
  and 
  getting 
  mixed 
  

  

  1 
  See 
  pages 
  27, 
  30. 
  

  

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  59 
  ) 
  

  

  