﻿166 
  OLDHAM: 
  GREAT 
  EARTHQUAKE 
  OF 
  1897, 
  

  

  which 
  movement 
  takes 
  place 
  is 
  nearly 
  horizontal 
  instead 
  of 
  nearly 
  

   vertical, 
  or 
  steeply 
  inclined. 
  Such 
  thrust-planes, 
  as 
  they 
  are 
  called, 
  

   have 
  now 
  been 
  recognised 
  as 
  a 
  common 
  structural 
  feature, 
  and 
  

   they 
  seldom, 
  if 
  ever, 
  occur 
  by 
  themselves, 
  but 
  are 
  accompanied 
  by 
  a 
  

   number 
  of 
  reversed 
  faults 
  of 
  ordinary 
  type, 
  running 
  upwards, 
  at 
  steep 
  

   inclination, 
  to 
  the 
  surface. 
  

  

  In 
  fig. 
  17 
  is 
  reproduced 
  a 
  portion 
  of 
  the 
  section 
  east 
  from 
  

   Quinaig, 
  as 
  drawn 
  by 
  the 
  Geological 
  Survey 
  of 
  Scotland, 
  1 
  showing 
  

   the 
  thrust-planes 
  T 
  T 
  and 
  the 
  minor 
  thrusts, 
  1 
  1. 
  If 
  this 
  were 
  

  

  SeaS, 
  of 
  

   GrUribeg* 
  

  

  T 
  T» 
  

  

  Fig 
  17. 
  Section 
  running 
  east 
  from 
  Quinaig, 
  in 
  the 
  northern 
  Highlands 
  of 
  Scotland. 
  

  

  enlarged 
  to 
  the 
  scale 
  of 
  the 
  Garo 
  and 
  Khasi 
  hills, 
  we 
  should 
  have 
  some- 
  

   thing 
  very 
  like 
  what 
  has 
  already 
  been 
  described 
  as 
  their 
  structure. 
  

  

  If 
  now 
  there 
  were 
  produced, 
  by 
  any 
  cause, 
  a 
  considerable 
  movement 
  

   along 
  the 
  great 
  thrust-plane 
  corresponding 
  to 
  T 
  1 
  — 
  which 
  it 
  must 
  be 
  

   recollected 
  is 
  buried 
  deep 
  below, 
  and 
  does 
  not 
  reach, 
  the 
  surface 
  — 
  

   there 
  would 
  be 
  smaller 
  movements 
  along 
  the 
  secondary 
  thrust-planes 
  

   T 
  T 
  and 
  the 
  tertiary 
  ones 
  t 
  t, 
  which 
  might 
  reach 
  the 
  surface 
  as 
  actual 
  

   faults, 
  but 
  would 
  very 
  probably 
  die 
  ©ut 
  and 
  give 
  rise 
  to 
  mere 
  changes 
  

   of 
  level 
  like 
  those 
  to 
  which 
  the 
  pools 
  in 
  the 
  Garo 
  and 
  Khasi 
  hills 
  

   were 
  due 
  ; 
  while 
  the 
  movement 
  along 
  the 
  thrust-plane 
  would 
  give 
  

   rise 
  to 
  the 
  horizontal 
  displacements 
  observed 
  in 
  the 
  trigonometri- 
  

   cally 
  fixed 
  peaks 
  in 
  the 
  Khasi 
  hills.* 
  

  

  We 
  have, 
  consequently, 
  an 
  hypothesis 
  which 
  satisfies 
  all 
  the 
  

   conditions 
  of 
  the 
  case. 
  It 
  accounts 
  for 
  the 
  permanent 
  change 
  

  

  1 
  Quart. 
  Jour. 
  Geol. 
  Soc, 
  XUV, 
  418 
  (1888). 
  

  

  2 
  See 
  appendix 
  G. 
  

  

  ( 
  166 
  ) 
  

  

  