﻿48 
  THEOBALD: 
  GEOLOGY 
  OF 
  PEGU. 
  

  

  up, 
  whereby 
  no 
  traces 
  of 
  bedding 
  or 
  intercalation 
  of 
  deposits 
  of 
  varying 
  

   composition 
  ever 
  took 
  place, 
  and 
  the 
  final 
  result 
  was 
  the 
  homogenous 
  

   one 
  we 
  see. 
  This 
  hypothesis 
  is, 
  of 
  course, 
  a 
  possible 
  one 
  ; 
  but 
  is 
  there 
  

   any 
  river 
  within 
  the 
  tropics 
  where 
  such 
  a 
  mode 
  of 
  deposition 
  can 
  be 
  confi- 
  

   dently 
  said 
  to 
  have 
  given 
  rise 
  to 
  such 
  a 
  bed 
  as 
  we 
  are 
  dealing 
  with 
  ? 
  The 
  

   Nile, 
  of 
  course, 
  is 
  cited 
  in 
  point 
  ; 
  but 
  one 
  requires 
  a 
  better 
  knowledge 
  of 
  its 
  

   deposits 
  before 
  the 
  cases 
  can 
  be 
  compared. 
  The 
  inundation 
  of 
  the 
  Nile 
  

   may 
  be 
  strictly 
  compared 
  with 
  the 
  inundations 
  of 
  the 
  Irrawadi 
  ; 
  but 
  the 
  

   result 
  is 
  practically 
  nil 
  in 
  the 
  case 
  of 
  the 
  latter 
  river. 
  It 
  is 
  open 
  to 
  

   great 
  doubt 
  if 
  so 
  much 
  is 
  deposited 
  on 
  the 
  surface 
  of 
  the 
  inundated 
  

   country, 
  save 
  in 
  the 
  immediate 
  vicinity 
  of 
  the 
  river 
  banks, 
  as 
  is 
  removed 
  

   from 
  it 
  by 
  scour 
  on 
  the 
  falling 
  of 
  the 
  river, 
  and 
  the 
  drainage 
  of 
  the 
  

   country, 
  which 
  thereon 
  takes 
  place, 
  as 
  I 
  will 
  shortly 
  explain. 
  Anyhow, 
  

   the 
  superficial 
  crust 
  of 
  fluviatile 
  silt 
  ranging, 
  according 
  to 
  circum- 
  

   stances, 
  from 
  a 
  few 
  inches 
  to 
  a 
  few 
  feet, 
  is 
  sufficiently 
  distinguishable, 
  as 
  

   a 
  rule, 
  from 
  the 
  homogenous 
  clay 
  whereon 
  it 
  rests 
  ; 
  and 
  to 
  suppose 
  that 
  

   the 
  whole 
  of 
  this 
  clay 
  has 
  originated 
  by 
  infinitesimal 
  accretions 
  to 
  a 
  

   land 
  surface 
  occasionally 
  flooded, 
  seems 
  not 
  to 
  be 
  warranted 
  by 
  our 
  

   experience 
  of 
  the 
  behaviour 
  of 
  modern 
  rivers, 
  and 
  least 
  of 
  all 
  by 
  such 
  

   rivers 
  as 
  now 
  occupy 
  the 
  area 
  in 
  question. 
  It 
  is 
  difficult, 
  indeed, 
  to 
  

   conceive 
  a 
  greater 
  contrast 
  between 
  the 
  composition 
  of 
  a 
  deep 
  bank 
  of 
  

   the 
  older 
  alluvium 
  and 
  a 
  similar 
  one 
  composed 
  of 
  modern 
  fluviatile 
  

   deposits 
  ; 
  and 
  this 
  contrast 
  may 
  be 
  studied 
  almost 
  anywhere 
  within 
  the 
  

   Gano-etic 
  valley. 
  The 
  ancient 
  alluvium 
  is 
  a 
  homogenous 
  clay. 
  The 
  newer 
  

   alluvium 
  is 
  compounded 
  of 
  beds 
  ranging 
  from 
  a 
  fine 
  silver 
  sand 
  to 
  a 
  fat 
  

   unctuous 
  loam, 
  thrown 
  down 
  not 
  in 
  extremely 
  thin 
  beds, 
  but 
  in 
  strong 
  

   one, 
  2 
  or 
  3 
  feet 
  beds, 
  which 
  are 
  often 
  composed 
  of 
  thin 
  laminar 
  

   strata, 
  but 
  each 
  thick 
  bed 
  representing 
  the 
  result 
  of 
  one 
  flood. 
  Thus 
  

   far 
  this 
  contrast 
  is 
  simple, 
  but 
  the 
  question 
  doubtless 
  remains 
  if 
  the 
  

   other 
  method 
  supposed 
  in 
  the 
  case 
  of 
  the 
  spill 
  of 
  a 
  river, 
  whose 
  annual 
  

   inundation 
  gives 
  merely 
  an 
  infinitesimal 
  addition 
  to 
  the 
  surface 
  growth 
  

   of 
  the 
  country, 
  would 
  not 
  adequately 
  explain 
  the 
  homogeneity 
  of 
  a 
  

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