﻿26 
  THEOBALD 
  : 
  GEOLOGY 
  OP 
  PEGU. 
  

  

  of 
  river 
  channel, 
  or 
  ground 
  occupied 
  by 
  river 
  deposits, 
  as 
  we 
  see 
  in 
  the 
  

  

  valley 
  'of 
  the 
  Ganges, 
  where 
  these 
  cover 
  entire 
  districts, 
  but 
  merely 
  a 
  

  

  well 
  marked 
  channel 
  rarely 
  exceeding 
  3 
  miles 
  in 
  breadth, 
  and 
  which 
  

  

  is 
  barely 
  sufficient 
  to 
  give 
  delivery 
  to 
  ordinary 
  floods, 
  though 
  of 
  this 
  

  

  narrow 
  area 
  but 
  a 
  small 
  portion 
  is 
  occupied 
  by 
  the 
  cold-weather 
  channel 
  

  

  of 
  the 
  river. 
  At 
  no 
  place 
  does 
  the 
  width 
  of 
  the 
  stream 
  between 
  its 
  

  

  permanent 
  banks* 
  carved 
  out 
  of 
  the 
  older 
  alluvium 
  exceed 
  6 
  miles 
  ; 
  and 
  

  

  it 
  only 
  attains 
  this 
  unusual 
  width 
  at 
  Tham-bya-deing, 
  where 
  the 
  

  

  Western 
  bank 
  of 
  the 
  river 
  is 
  very 
  low, 
  and 
  has 
  been 
  subjected 
  to 
  very 
  

  

  destructive 
  erosion 
  at 
  the 
  point 
  or 
  outlet 
  where 
  the 
  Bassein 
  river 
  is 
  

  

  given 
  off. 
  Indeed, 
  considering 
  the 
  low 
  nature 
  of 
  the 
  country, 
  and 
  a 
  fall 
  

  

  which, 
  I 
  believe, 
  exists 
  from 
  the 
  Irrawadi 
  at 
  this 
  point 
  to 
  the 
  Bassein 
  

  

  river, 
  it 
  seems 
  not 
  improbable 
  that 
  this 
  cutting 
  back, 
  would, 
  if 
  left 
  

  

  unchecked 
  by 
  man, 
  prove 
  the 
  first 
  step 
  towards 
  the 
  formation 
  of 
  a 
  great 
  

  

  delivery 
  channel 
  of 
  the 
  Irrawadi 
  into 
  the 
  Bassein 
  river, 
  along 
  the 
  course 
  

  

  of 
  the 
  small 
  creek 
  before 
  alluded 
  to, 
  which 
  has 
  now 
  been 
  closed 
  by 
  the 
  

  

  engineers. 
  At 
  Prome, 
  48 
  miles 
  above 
  Menghyee, 
  the 
  assumed 
  head 
  of 
  

  

  the 
  delta, 
  the 
  ordinary 
  flood-rise 
  of 
  the 
  Irrawadi 
  according 
  to 
  Colonel 
  

  

  Stoddart 
  (vide 
  Report 
  in 
  Supplement 
  to 
  British 
  Burmah 
  Gazette, 
  

  

  September 
  17th, 
  1870, 
  and 
  original 
  in 
  Public 
  Works 
  Department 
  Office), 
  

  

  is 
  from 
  33 
  to 
  34 
  feet 
  above 
  the 
  lowest 
  level 
  of 
  the 
  river; 
  but 
  in 
  1868, 
  

  

  the 
  great 
  flood 
  of 
  that 
  year 
  rose 
  to 
  a 
  height 
  of 
  36*23 
  feet, 
  or 
  2 
  feet 
  

  

  higher 
  than 
  any 
  previously 
  recorded 
  flood. 
  The 
  discharge 
  per 
  second 
  

  

  during 
  the 
  great 
  flood, 
  was 
  1,424,000 
  cubic 
  feet 
  per 
  second, 
  whilst 
  the 
  

  

  discharge 
  of 
  an 
  ordinary 
  flood 
  amounts 
  only 
  to 
  1,312,000 
  cubic 
  feet,f 
  

  

  * 
  My 
  use 
  of 
  the 
  term 
  'permanent 
  banks' 
  may 
  be 
  objected 
  to, 
  as 
  high 
  floods 
  establish 
  

   a 
  spill 
  over 
  them 
  ; 
  but 
  as 
  they 
  are 
  carved 
  out 
  of 
  the 
  older 
  alluvium 
  as 
  distinguished 
  from 
  

   the 
  modern 
  river's 
  deposits, 
  I 
  believe 
  my 
  use 
  of 
  the 
  term 
  is 
  correct. 
  

  

  f 
  I 
  have 
  been 
  given 
  to 
  understand 
  by 
  J. 
  R. 
  Gordon, 
  Engineer 
  at 
  Henzada, 
  that 
  by 
  

   a 
  series 
  of 
  careful 
  and 
  extended 
  experiments 
  he 
  has 
  found 
  that 
  the 
  calculations 
  of 
  discharge 
  

   made 
  by 
  Colonel 
  Stoddart 
  are 
  somewhat 
  below 
  the 
  truth, 
  the 
  ordinary 
  flood 
  maximum 
  of 
  

   31st 
  August 
  1872 
  giving 
  a 
  discharge 
  per 
  second 
  of 
  1,442,007 
  cubic 
  feet 
  with 
  a 
  mean 
  

   velocity 
  of 
  6451 
  feet 
  per 
  second. 
  

   ( 
  214 
  ) 
  

  

  