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  OLDHAM: 
  GREAT 
  EARTHQUAKE 
  OF 
  1897. 
  

  

  adhesion 
  of 
  the 
  subsoil 
  to 
  the 
  underlying 
  rock 
  is 
  great, 
  where 
  its 
  

   thickness 
  is 
  small, 
  or 
  where 
  the 
  violence 
  of 
  the 
  shock 
  is 
  not 
  great 
  

   enough, 
  the 
  slippage 
  of 
  the 
  surface 
  layer 
  does 
  not 
  amount 
  to 
  a 
  land- 
  

   slip, 
  and 
  in 
  these 
  cases 
  the 
  hillsides 
  are 
  found 
  to 
  be 
  scarred 
  with 
  

   fissures. 
  At 
  the 
  other 
  extreme, 
  _ 
  the 
  momentum 
  imparted 
  to 
  the 
  

   surface 
  layer 
  may 
  be 
  so 
  great 
  that 
  an 
  actual 
  outward 
  pull 
  is 
  set 
  up, 
  

   sufficient 
  to 
  overcome 
  the 
  resistance, 
  both 
  of 
  gravity 
  and 
  the 
  adhe- 
  

   sion 
  of 
  the 
  subsoil 
  to 
  the 
  rock, 
  and 
  then 
  we 
  have 
  not 
  merely 
  a 
  land- 
  

   slip, 
  but 
  the 
  whole 
  face 
  of 
  the 
  hill 
  shot 
  bodily 
  off. 
  The 
  condition-s 
  

   that 
  allow 
  of 
  this 
  appear 
  to 
  be 
  rare, 
  but 
  they 
  certainly 
  did 
  occur 
  in 
  

   some 
  of 
  the 
  high 
  scarps 
  of 
  the 
  Khasi 
  and 
  Garo 
  Hills. 
  

  

  So 
  far 
  I 
  have 
  spoken 
  only 
  of 
  the 
  landslips 
  produced 
  by 
  the 
  dis- 
  

   placement 
  of 
  the 
  more 
  or 
  less 
  weathered 
  surface 
  layer 
  ; 
  they 
  seldom: 
  

   extend 
  deep 
  into 
  the 
  hill, 
  and 
  resemble 
  in 
  all 
  their 
  characters 
  ordi- 
  

   nary 
  landslips 
  of 
  the 
  same 
  scale. 
  Besides 
  these, 
  the 
  high 
  sandstone 
  

   scarps 
  of 
  the 
  southern 
  edge 
  of 
  the 
  Khasi 
  and 
  Garo 
  Hills 
  exhibit 
  land- 
  

   slips 
  due 
  to 
  the 
  throwing 
  off 
  of 
  a 
  greater 
  or 
  less 
  width 
  of 
  solid 
  sand- 
  

   stone, 
  in 
  a 
  manner 
  precisely 
  analogous 
  to 
  that 
  described 
  in 
  Chap- 
  

   ter 
  VI 
  but 
  on 
  a 
  larger 
  scale. 
  

  

  In 
  the 
  case 
  of 
  both 
  these 
  forms 
  of 
  landslips, 
  the 
  part 
  of 
  the 
  hill 
  

   which 
  is 
  left 
  standing 
  is 
  always 
  scarred 
  with 
  deep 
  fissures, 
  extending 
  

   more 
  or 
  less 
  parallel 
  to 
  the 
  free 
  face 
  of 
  the 
  fall, 
  and 
  due 
  to 
  a 
  partial 
  

   detachment 
  of 
  the 
  material 
  between 
  them 
  and 
  the 
  edge 
  of 
  the 
  actual 
  

   slip. 
  These 
  fissures 
  are 
  very 
  conspicuous 
  on 
  the 
  Bctlpakram 
  

   plateau 
  west 
  of 
  the 
  Mahadeo 
  valley, 
  as 
  shown 
  in 
  Plate 
  XXVII, 
  fig. 
  1, 
  

   but 
  they 
  are 
  in 
  all 
  cases 
  a 
  secondary 
  effect 
  of 
  the 
  transmitted 
  earth- 
  

   quake 
  wave, 
  just 
  as 
  the 
  sand 
  vents 
  and 
  earth 
  fissures 
  treated 
  in 
  the 
  

   last 
  chapter. 
  

  

  Having 
  noticed 
  the 
  mode 
  of 
  formation 
  of 
  the 
  landslips, 
  we 
  have 
  

   now 
  to 
  consider 
  the 
  limitations 
  on 
  their 
  formation. 
  Foremost 
  among 
  

   these 
  must 
  be 
  placed 
  the 
  violence 
  of 
  the 
  earthquake, 
  for 
  it 
  is 
  only 
  

   under 
  very 
  exceptional 
  circumstances 
  that 
  a 
  wave 
  of 
  low 
  velocity, 
  or 
  

   acceleration, 
  of 
  wave 
  particle 
  could 
  give 
  rise 
  to 
  landslips. 
  Given 
  a 
  

   ( 
  U2 
  ) 
  

  

  