﻿23 
  

  

  Section 
  5. 
  — 
  (d). 
  Pachmari 
  group. 
  

   This 
  group 
  is 
  for 
  the 
  most 
  part 
  the 
  simplest 
  and 
  best 
  defined 
  of 
  the 
  

  

  whole 
  series. 
  Consisting 
  entirely 
  of 
  massive 
  

   Its 
  extension. 
  J 
  

  

  banks 
  of 
  sandstone 
  with 
  overlapping 
  superposi- 
  

   tion 
  among 
  themselves, 
  it 
  is 
  generally 
  in 
  sharp 
  contact 
  with 
  clay 
  depo- 
  

   sits 
  on 
  the 
  north, 
  and 
  with 
  shaly 
  carbonaceous 
  beds 
  at 
  its 
  base 
  on 
  the 
  

   south. 
  There 
  is, 
  however, 
  sufficient 
  evidence 
  of 
  its 
  close 
  relationship 
  to 
  

   the 
  beds 
  above 
  and 
  below 
  it; 
  that 
  it 
  is 
  but 
  a 
  sub-division 
  of 
  a 
  continu- 
  

   ous 
  series 
  of 
  deposits. 
  It 
  measures 
  twelve 
  miles 
  across 
  where 
  widest, 
  in 
  

   about 
  the 
  exact 
  centre 
  of 
  the 
  basin. 
  For 
  the 
  greater 
  part 
  of 
  this 
  dis- 
  

   tance, 
  on 
  the 
  north 
  side, 
  there 
  is 
  a 
  steady 
  dip 
  of 
  10°, 
  flattening 
  some- 
  

   what 
  on 
  the 
  rise. 
  This 
  gives 
  a 
  thickness 
  of 
  at 
  least 
  8,000 
  feet. 
  As 
  the 
  

   southern 
  cliffs 
  become 
  worn 
  back 
  to 
  east 
  and 
  west 
  of 
  the 
  central 
  line 
  

   the 
  dip 
  produces 
  a 
  decreasing 
  elevation 
  of 
  the 
  range, 
  and 
  also 
  of 
  the 
  

   lower 
  boundary 
  of 
  the 
  group. 
  At 
  Rorighat 
  and 
  Almod, 
  in 
  the 
  central 
  

   position, 
  the 
  underlying 
  shales, 
  of 
  (e), 
  crop 
  out 
  at 
  a 
  height 
  of 
  about 
  2,500 
  

   feet, 
  and 
  some 
  700 
  feet 
  over 
  the 
  gorges 
  of 
  the 
  Denwa 
  and 
  Sonbudra. 
  At 
  

   twelve 
  miles 
  to 
  east-north-east, 
  where 
  the 
  Denwa 
  begins 
  to 
  cut 
  through 
  the 
  

   range, 
  the 
  base 
  of 
  the 
  sandstone 
  is 
  at 
  the 
  level 
  of 
  the 
  river. 
  The 
  group 
  

   is 
  here 
  reduced 
  to 
  seven 
  miles 
  in 
  width, 
  and 
  throughout 
  the 
  gorge 
  

   there 
  is 
  a 
  steady 
  northerly 
  dip 
  of 
  at 
  least 
  10° 
  in 
  unbroken 
  sandstone 
  

   giving 
  a 
  thickness 
  of 
  6,000 
  feet. 
  Similarly 
  at 
  fourteen 
  miles 
  to 
  the 
  west 
  

   the 
  Sonbudra 
  Cuts 
  a 
  gorge 
  four 
  miles 
  long, 
  giving 
  a 
  thickness 
  of 
  3,500 
  

   feet 
  ; 
  and 
  fifteen 
  miles 
  further 
  west, 
  the 
  Tawa 
  cuts 
  a 
  straight 
  gor«-e 
  of 
  

   two 
  miles 
  through 
  the 
  same 
  inclined 
  sandstones, 
  giving 
  a 
  thickness 
  of 
  

   1,700 
  feet. 
  

  

  The 
  interesting 
  stratigraphical 
  question 
  suggests 
  itself, 
  what 
  may 
  

   Its 
  prolongation 
  in 
  be 
  the 
  prolongation 
  to 
  the 
  deep 
  of 
  this 
  great 
  

   depth 
  - 
  band 
  of 
  hard 
  rock 
  ? 
  It 
  is 
  a 
  point 
  of 
  critical 
  im- 
  

  

  portance, 
  as 
  bearing 
  upon 
  the 
  possibility 
  of 
  working 
  the 
  coal 
  which 
  may 
  

   be 
  presumed' 
  to 
  occur 
  beneath 
  all 
  these 
  formations 
  near 
  the 
  bottom 
  of 
  

  

  ( 
  155 
  ) 
  

  

  