﻿54 
  BOSE 
  : 
  GEOLOGY 
  OF 
  THE 
  LOWER 
  NARBADA 
  VALLEY. 
  

  

  At 
  Chandgarh, 
  the 
  trap 
  is 
  seen 
  superposed 
  on 
  the 
  metamorphics 
  . 
  

   Further 
  west, 
  however, 
  it 
  occupies 
  the 
  valley 
  between 
  ridges 
  of 
  Vindhyan 
  

   rocks, 
  as 
  near 
  Pamakheri. 
  The 
  fact 
  of 
  the 
  occurrence 
  of 
  a 
  dyke 
  a 
  mile 
  

   and 
  a 
  half 
  north 
  of 
  the 
  place, 
  as 
  well 
  as 
  of 
  another 
  (slightly 
  exposed) 
  at 
  

   Sakerghat, 
  makes 
  it 
  almost 
  certain 
  that 
  this 
  trap 
  was 
  erupted 
  out 
  of 
  a 
  

   local 
  fissure. 
  

  

  In 
  the 
  bed 
  of 
  the 
  Narbada, 
  at 
  Boria, 
  two 
  miles 
  south-west 
  of 
  Chand- 
  

   garh, 
  a 
  good 
  dyke 
  is 
  seen 
  striking 
  very 
  nearly 
  east- 
  west. 
  It 
  runs 
  pretty 
  

   straight 
  down 
  to 
  Jamoti 
  (or 
  Palasi), 
  masses 
  of 
  the 
  Brjawar 
  limestone 
  

   being 
  found 
  resting 
  on 
  it 
  at 
  places. 
  At 
  the 
  last-mentioned 
  place, 
  it 
  

   apparently 
  divides, 
  passing 
  round 
  an 
  island 
  composed 
  of 
  highly 
  disturbed, 
  

   nearly 
  vertical, 
  Vindhyans; 
  the 
  northern 
  branch 
  is 
  lost 
  under 
  deep 
  

   water, 
  but 
  reappears 
  at 
  the 
  western 
  end 
  of 
  the 
  islet 
  ; 
  the 
  southern 
  

   branch 
  is 
  traced 
  to 
  some 
  distance 
  and 
  then 
  lost 
  under 
  the 
  Vindhyans. 
  

  

  Numerous 
  small 
  dykes 
  occur 
  between 
  Chandgarh 
  and 
  Mandhata. 
  

   These 
  are, 
  however, 
  not 
  traceable 
  to 
  any 
  considerable 
  distance. 
  

  

  The 
  columnar 
  dyke 
  in 
  the 
  Dhar 
  forest 
  has 
  been 
  already 
  described 
  ; 
  

   there 
  is 
  a 
  similar 
  dyke 
  in 
  the 
  Deccan-trap 
  at 
  Palasi 
  in 
  the 
  north-eastern 
  

   corner 
  of 
  the 
  same 
  forest, 
  close 
  to 
  the 
  Vindhyan 
  range. 
  Here, 
  too, 
  it 
  

   forms 
  a 
  hill 
  elevated 
  a 
  couple 
  of 
  hundred 
  feet 
  above 
  the 
  general 
  level 
  of 
  

   the 
  valley 
  ; 
  the 
  columns 
  are 
  horizontal, 
  except 
  on 
  the 
  northern 
  face 
  of 
  

   the 
  hill, 
  where 
  they 
  are 
  highly 
  inclined. 
  

  

  There 
  is 
  another 
  dyke 
  hill 
  of 
  horizontal 
  columns 
  also 
  in 
  the 
  Deccan 
  

   trap, 
  two 
  miles. 
  north 
  of 
  Tharwa 
  (near 
  Katkut). 
  

  

  Opposite 
  the 
  town 
  of 
  Mandlesar 
  (once 
  the 
  seat 
  of 
  a 
  small 
  British 
  

   cantonment) 
  there 
  is 
  seen 
  in 
  the 
  bed 
  of 
  the 
  Narbada 
  in 
  the 
  dry 
  season 
  

   a 
  low 
  ridge 
  running 
  in 
  a 
  north-east 
  — 
  south-west 
  direction. 
  The 
  rock 
  

   composing 
  it 
  is 
  found 
  to 
  be 
  crystalline, 
  the 
  central 
  portion 
  being 
  much 
  

   more 
  so 
  than 
  the 
  lateral. 
  The 
  triclinic 
  felspar 
  is 
  quite 
  large 
  enough 
  to 
  

   be 
  well 
  seen 
  with 
  the 
  unassisted 
  eye 
  ; 
  the 
  augite 
  is 
  also 
  large, 
  coloured 
  

   dark 
  brown, 
  irregular, 
  and 
  full 
  of 
  cracks. 
  [See 
  Plate, 
  fig. 
  2.] 
  

  

  The 
  texture 
  of 
  the 
  rock, 
  and 
  the 
  straightness 
  of 
  the 
  direction 
  

   in 
  which 
  the 
  ridge 
  runs 
  raise 
  a 
  presumption 
  in 
  favour 
  of 
  its 
  being 
  

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  54 
  ) 
  

  

  