﻿50 
  BOSE 
  : 
  GEOLOGY 
  OF 
  THE 
  LOWER 
  NARBADA 
  VALLEY. 
  

  

  Physical 
  geology 
  of 
  the 
  Cretaceous 
  basin. 
  — 
  The 
  following' 
  points 
  have 
  

   been 
  already 
  indicated 
  : 
  — 
  

  

  (1) 
  The 
  nodular 
  limestone 
  becomes 
  attenuated 
  westward 
  ; 
  west 
  of 
  

  

  the 
  Wagni 
  river 
  it 
  is 
  highly 
  f 
  ossilif 
  erous, 
  but 
  east 
  of 
  that 
  river 
  

   fossils 
  are 
  rarer. 
  

  

  (2) 
  The 
  argillaceous 
  limestone, 
  and 
  the 
  overlying 
  coralline 
  limestone 
  

  

  also, 
  both 
  thin 
  out 
  to 
  the 
  west 
  ; 
  and 
  west 
  of 
  the 
  Wagni, 
  they 
  

   have 
  been 
  noticed 
  at 
  only 
  a 
  few 
  localities, 
  forming 
  short 
  and 
  

   narrow 
  bands. 
  1 
  

  

  (3) 
  The 
  Lametas, 
  unlike 
  the 
  groups 
  just 
  mentioned, 
  thicken 
  west- 
  

  

  ward, 
  and 
  rest 
  generally 
  upon 
  the 
  nodular 
  limestone. 
  

   The 
  resultant 
  movement 
  of 
  slow 
  terrestrial 
  depression 
  which 
  had 
  

   been 
  going 
  on 
  in 
  the 
  neocomian 
  sea 
  (the 
  northern 
  configuration 
  of 
  

   which 
  probably 
  coincided 
  with 
  the] 
  southern 
  outline 
  of 
  the 
  present 
  

   Vindhyan 
  range) 
  continued 
  during 
  the 
  earliest 
  portion 
  of 
  the 
  upper 
  creta- 
  

   ceous 
  epoch. 
  But 
  towards 
  the 
  end 
  of 
  the 
  nodular-limestone 
  age, 
  a 
  

   general, 
  gradual, 
  elevating 
  movement 
  set 
  in 
  west 
  of 
  the 
  Wagni, 
  lasting 
  

   very 
  nearly 
  until 
  the 
  conclusion 
  of 
  that 
  epoch 
  ; 
  and 
  the 
  subsidence 
  

   became 
  restricted 
  to 
  the 
  area 
  east 
  of 
  the 
  Wagni, 
  until 
  the 
  deposition 
  

   of 
  the 
  coralline 
  beds, 
  when 
  the 
  movement 
  was 
  reversed. 
  Thus 
  the 
  

   attenuated 
  condition 
  of 
  the 
  nodular 
  limestone 
  in 
  the 
  western 
  portion 
  

   of 
  the 
  cretaceous 
  basin 
  would 
  be 
  accounted 
  for 
  by 
  its 
  having 
  been 
  sub- 
  

   jected 
  to 
  marine 
  denudation, 
  while 
  raising 
  its 
  head 
  above 
  the 
  sea, 
  and 
  

   its 
  greater 
  thickness 
  eastward, 
  would 
  be 
  attributed 
  to 
  its 
  preservation 
  in 
  

   a 
  subsiding 
  bay. 
  The 
  argillaceous 
  and 
  coralline 
  limestones 
  would 
  be 
  

   well 
  protected 
  and 
  deposited 
  in 
  greater 
  and 
  increasing 
  depths 
  in 
  the 
  

   latter 
  area 
  ; 
  whereas, 
  in 
  the 
  former, 
  they 
  would 
  be 
  so 
  liable 
  to 
  be 
  removed 
  

   the 
  moment 
  they 
  were 
  thrown 
  down, 
  that 
  not 
  more 
  than 
  a 
  few 
  patches 
  

   could 
  be 
  expected 
  to 
  be 
  preserved. 
  We 
  should 
  expect 
  the 
  organisms 
  

   that 
  lived 
  in 
  the 
  coralline 
  sea 
  to 
  have 
  been 
  deeper-sea 
  forms 
  than 
  those 
  

   imbedded 
  in 
  the 
  Deola 
  and 
  Chirakhan 
  marl, 
  and 
  such 
  is 
  the 
  case. 
  

  

  3 
  In 
  his 
  necessarily 
  hurried 
  preliminary 
  survey 
  Mr. 
  Blanford 
  did 
  not 
  notice 
  these 
  

   hands 
  (see 
  Manual, 
  p. 
  295). 
  

  

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  50 
  ] 
  

  

  