﻿20 
  EEDDEN 
  : 
  GEOLOGY 
  OF 
  KATHlAWAlt 
  PENINSULA 
  IN 
  GUZERAT. 
  

  

  meratic, 
  while 
  the 
  later 
  outbursts 
  are 
  more 
  trachytic, 
  f 
  elsitic, 
  and 
  dioritic, 
  

  

  occasionally 
  with 
  lenticular 
  masses 
  and 
  thin 
  bands 
  of 
  uncrystallized 
  

  

  rock, 
  resembling- 
  obsidian, 
  or 
  pitchstone. 
  1 
  Some 
  of 
  the 
  trap-flows 
  are 
  

  

  thoroughly 
  crystalline; 
  often 
  showing 
  a 
  porphyritic 
  appearance 
  on 
  the 
  

  

  weathered 
  surface; 
  others 
  are 
  more 
  homogeneous, 
  compact, 
  and 
  apha- 
  

  

  nitic 
  ; 
  while 
  others 
  again 
  are 
  more 
  or 
  less 
  decomposed, 
  many 
  of 
  these 
  are 
  

  

  highly 
  amygdaloidal. 
  In 
  the 
  western 
  part 
  of 
  the 
  field, 
  especially 
  north 
  

  

  of 
  Rajkot, 
  zeolites 
  are 
  abundant 
  in 
  the 
  decomposed 
  

   Zeolites 
  abundant. 
  . 
  

  

  traps, 
  occurring 
  often 
  in 
  large 
  crystalline 
  masses 
  ; 
  

  

  and 
  geodes 
  of 
  agate 
  and 
  chalcedony, 
  lined 
  with 
  quartz 
  crystals, 
  are 
  also 
  

  

  numerous. 
  

  

  The 
  traps 
  are, 
  as 
  a 
  rule, 
  thinly 
  bedded 
  : 
  in 
  a 
  scarp 
  of 
  320 
  feet, 
  nine 
  

   miles 
  south 
  of 
  Chotila, 
  one 
  may 
  count, 
  from 
  a 
  distance 
  of 
  many 
  miles, 
  at 
  

   least 
  eight 
  superimposed 
  flows, 
  thus 
  giving 
  an 
  average 
  of 
  40 
  feet 
  for 
  

   each 
  ; 
  but 
  several 
  of 
  them 
  are 
  not 
  half 
  this 
  thickness, 
  and 
  probably 
  thers 
  

   are 
  many 
  more 
  flows 
  than 
  can 
  be 
  superficially 
  discerned. 
  It 
  may 
  be 
  

   mentioned 
  that 
  the 
  great 
  dyke 
  passing 
  Mewasa 
  has 
  cut 
  through 
  all 
  the 
  

   beds 
  in 
  the 
  scarp 
  just 
  referred 
  to. 
  

  

  The 
  nature 
  of 
  the 
  floor, 
  wherever 
  the 
  traps 
  rest 
  on 
  Umia 
  sandstones, 
  

  

  is 
  often 
  irregular 
  and 
  uneven, 
  showing 
  distinct 
  

   Varied 
  floor. 
  • 
  . 
  

  

  unconformity. 
  The 
  annexed 
  sketch 
  section, 
  show- 
  

   ing 
  such 
  an 
  unconformity, 
  was 
  taken 
  in 
  a 
  quarry 
  at 
  the 
  sandstone 
  inlier 
  

   between 
  6 
  and 
  7 
  miles 
  west-south-west 
  of 
  Chotila. 
  

  

  I 
  have 
  already 
  stated 
  that 
  the 
  

   basal 
  part 
  of 
  the 
  trappean 
  series 
  

   is 
  frequently 
  very 
  miscellaneous 
  ; 
  

   but 
  this 
  is 
  not 
  always 
  the 
  case 
  ; 
  

   notably 
  in 
  the 
  hilly 
  country 
  west 
  

   and 
  northwest 
  of 
  Chotila, 
  where 
  sketch 
  section 
  

  

  CL 
  Trap. 
  p. 
  S 
  cuxcts 
  to 
  rut, 
  . 
  

  

  a 
  homogeneous 
  trap-flow 
  is 
  seen 
  

  

  resting, 
  with 
  apparent 
  conformity 
  of 
  bedding, 
  upon 
  Umia 
  sandstone, 
  

  

  1 
  It 
  is 
  nearer 
  obsidian 
  tban 
  pitchstone; 
  its 
  hardness 
  is 
  from 
  6 
  to 
  7; 
  it 
  is 
  slightly 
  de- 
  

   composed 
  by 
  acid. 
  Before 
  the 
  blow-pipe, 
  however, 
  a 
  splinter 
  fuses 
  to 
  a 
  frothy 
  light-grey 
  

   glass., 
  

  

  ( 
  92 
  ) 
  

  

  