﻿FISSURES 
  AND 
  VENTS. 
  log 
  

  

  In 
  the 
  foregoing 
  passages 
  the 
  bearing 
  of 
  the 
  phenomena, 
  which 
  

   were 
  observed 
  on 
  the 
  formation 
  of 
  earth 
  fissures 
  and 
  sand 
  vents 
  has 
  

   been 
  discussed 
  ; 
  we 
  must 
  now 
  consider 
  their 
  extent 
  and 
  distribution. 
  

   Before 
  entering 
  into 
  this, 
  however, 
  it 
  may 
  be 
  well 
  to 
  notice 
  one 
  

   qualification 
  which 
  must 
  be 
  borne 
  in 
  mind 
  whenever 
  it 
  is 
  said 
  that 
  

   they 
  were 
  universal 
  or 
  generally 
  distributed 
  over 
  any 
  specified 
  area, 
  

   namely 
  that 
  they 
  can 
  only 
  occur 
  where 
  the 
  local 
  conditions 
  are 
  

   favourable. 
  

  

  The 
  whole 
  of 
  the 
  hill 
  area 
  must, 
  of 
  course 
  be 
  excluded, 
  but 
  even 
  

   in 
  the 
  alluvium 
  there 
  are 
  large 
  tracts 
  of 
  an 
  older 
  alluvium, 
  charac- 
  

   terised 
  by 
  a 
  much 
  greater 
  compactness 
  than 
  the 
  newer. 
  This 
  

   older 
  alluvium 
  is 
  usually 
  of 
  a 
  red 
  colour 
  and 
  forms 
  elevated 
  tracts, 
  

   rising 
  from 
  the 
  newer, 
  of 
  which 
  the 
  Madhupur 
  jungle, 
  lying 
  between 
  

   Dacca 
  and 
  Maimansingh, 
  is 
  the 
  best 
  known, 
  though 
  not 
  the 
  only 
  one. 
  

   To 
  the 
  north 
  of 
  the 
  Ganges 
  and 
  in 
  the 
  Assam 
  Valley 
  there 
  are 
  several 
  

   tracts 
  of 
  similar 
  alluvium, 
  which 
  have 
  everywhere 
  escaped 
  Assuring 
  

   or 
  the 
  formation 
  of 
  sand 
  vents, 
  owing 
  to 
  their 
  greater 
  compactness 
  

   and 
  the 
  absence 
  of 
  beds 
  of 
  loose 
  waterlogged 
  sand. 
  Even 
  in 
  the 
  

   newer 
  alluvium 
  such 
  beds 
  of 
  sand 
  are 
  not 
  everywhere 
  near 
  enouo-h 
  

   to 
  the 
  surface 
  to 
  allow 
  of 
  the 
  production 
  of 
  the 
  effects 
  described 
  in 
  

   this 
  chapter, 
  but 
  with 
  these 
  exceptions 
  it 
  may 
  be 
  said 
  that 
  fissures 
  

   and 
  sand 
  vents 
  were 
  universal 
  throughout 
  the 
  Goalpara 
  and 
  Kamrup 
  

   districts, 
  the 
  western 
  part 
  of 
  Darrang 
  and 
  the 
  greater 
  part 
  of 
  

   Nowgong, 
  Sylhet, 
  and 
  the 
  northern 
  parts 
  of 
  Cachar. 
  In 
  Bengal 
  

   they 
  were 
  equally 
  prevalent 
  throughout 
  Rangpur, 
  Dinajpur, 
  Raj- 
  

   shahi, 
  Maldah, 
  Purniah, 
  Pabna, 
  Bogra, 
  Maimansingh, 
  and 
  the 
  greater 
  

   part 
  of 
  Dacca. 
  

  

  Outside 
  the 
  area 
  over 
  which 
  they 
  were 
  widespread, 
  there 
  is 
  a 
  

   larger 
  area 
  where 
  they 
  were 
  less 
  frequent. 
  Fissures 
  and 
  sand 
  vents 
  

   are 
  said 
  to 
  have 
  been 
  formed 
  in 
  the 
  Murang 
  district 
  of 
  the 
  Nepal 
  

   Tarai, 
  north 
  of 
  Purniah. 
  In 
  Bhagalpur 
  a 
  few 
  were 
  found 
  in 
  the 
  

   Supul 
  sub-division, 
  and 
  near 
  Colgong, 
  on 
  the 
  banks 
  of 
  the 
  Kosi 
  and 
  

   Ganges, 
  respectively. 
  A 
  fissure 
  50 
  feet 
  long 
  by 
  1 
  foot 
  broad 
  is 
  said 
  to 
  

  

  ( 
  109 
  ) 
  

  

  