﻿TRAP 
  DYKES. 
  29 
  

  

  enormous 
  volume 
  of 
  discharge 
  that 
  these 
  numerous 
  and 
  extensive 
  

   fissures 
  afforded, 
  there 
  is 
  no 
  need 
  to 
  look 
  for 
  volcanic 
  vents, 
  or 
  foci, 
  

   although, 
  in 
  the 
  Girnar 
  mountain 
  and 
  a 
  few 
  other 
  hills, 
  there 
  is 
  some 
  

   evidence 
  of 
  the 
  latter 
  kind 
  of 
  discharge 
  at 
  the 
  close 
  of 
  the 
  trappean 
  

   outflow. 
  

  

  The 
  character 
  of 
  the 
  dyke-trap 
  generally 
  differs 
  from 
  that 
  of 
  the 
  

   adjacent 
  flows, 
  or 
  beds; 
  this 
  may 
  probably 
  arise 
  

   from 
  the 
  difference 
  of 
  condition 
  under 
  which 
  the 
  

   matter 
  solidified. 
  The 
  rock, 
  in 
  very 
  many 
  of 
  the 
  dykes, 
  has 
  a 
  prismatic, 
  

   or 
  columnar 
  structure, 
  transverse 
  to 
  the 
  direction 
  of 
  the 
  dyke. 
  In 
  

   very 
  few 
  instances 
  was 
  the 
  dyke-trap 
  observed 
  to 
  be 
  amygdaloidal, 
  or 
  

   vesicular 
  ; 
  and 
  where 
  such 
  is 
  the 
  case, 
  it 
  may 
  be 
  presumed 
  to 
  occur 
  near 
  

   the 
  surface, 
  or 
  overflow 
  : 
  at 
  this 
  latter 
  point 
  a 
  dyke 
  would 
  naturally 
  

   become 
  ill-defined 
  and 
  blended 
  with 
  the 
  lateral 
  flow. 
  This, 
  indeed, 
  appears 
  

   to 
  be 
  the 
  case 
  in 
  the 
  dyke 
  at 
  Harmaria, 
  north 
  of 
  Mewasa, 
  where 
  the 
  

   dyke-rock, 
  in 
  places, 
  is 
  indistinguishable 
  from 
  the 
  adjoining 
  bed, 
  or 
  

   flow, 
  and 
  is 
  only 
  traceable 
  as 
  a 
  dyke 
  here 
  and 
  there 
  by 
  irregular 
  lines 
  of 
  

   contact. 
  

  

  The 
  long 
  dyke 
  west 
  of 
  Charkhari 
  (north 
  of 
  Mewasa) 
  displays 
  a 
  

   different 
  structure 
  at 
  different 
  levels 
  within 
  its 
  

   walls; 
  where 
  seen 
  in 
  the 
  bed 
  of 
  a 
  nala 
  it 
  has 
  a 
  

   fissile 
  splintery 
  structure, 
  is 
  very 
  close-grained, 
  or 
  micro-crystalline; 
  

   while, 
  at 
  a 
  higher 
  level 
  of 
  the 
  same 
  dyke 
  in 
  the 
  hill 
  ridge 
  above, 
  the 
  

   rock 
  has 
  lost 
  the 
  characters 
  just 
  described, 
  and 
  has 
  assumed 
  a 
  spheroidal, 
  

   or 
  boulder-like, 
  structure 
  on 
  the 
  weathered 
  surface, 
  and 
  internally 
  is 
  

   more 
  distinctly 
  crystalline. 
  

  

  The 
  Khokhri 
  dyke 
  (south 
  of 
  Gondal) 
  is 
  120 
  feet 
  wide 
  east 
  of 
  the 
  

   town, 
  and 
  may 
  be 
  as 
  much 
  as 
  200 
  feet 
  in 
  some 
  parts, 
  but 
  its 
  decomposed 
  

   sides 
  and 
  walls 
  are 
  not 
  clearly 
  defined. 
  

  

  The 
  great 
  dyke 
  running 
  eastward 
  from 
  Karmal 
  Kotra, 
  and 
  twice 
  

   crossed 
  by 
  the 
  Bhadar 
  river, 
  east 
  of 
  Gondal, 
  is 
  more 
  like 
  an 
  irregular 
  

   intrusion 
  than 
  a 
  fissure 
  dyke. 
  It 
  is 
  very 
  irregular 
  without 
  definite 
  

   walls, 
  and 
  in 
  one 
  place 
  it 
  has 
  a 
  bedded 
  appearance. 
  

  

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