﻿138 
  Geological 
  Society: 
  — 
  

  

  and 
  aplite. 
  In 
  each 
  case 
  the 
  greater 
  resistance 
  offered 
  to 
  denu- 
  

   dation 
  is 
  related 
  to 
  the 
  presence 
  of 
  less 
  foliated 
  and 
  more 
  felsic 
  

   rocks 
  than 
  are 
  found 
  in 
  the 
  adjacent 
  plains. 
  There 
  remains 
  a 
  

   fourth 
  type 
  — 
  perhaps 
  the 
  most 
  abundant 
  — 
  in 
  which 
  no 
  differences 
  

   have 
  been 
  recognized. 
  Many 
  of 
  these 
  seem 
  to 
  be 
  isolated 
  relics 
  

   of 
  gneissic 
  escarpments 
  ; 
  and 
  it 
  is 
  suggested 
  that 
  desert 
  erosion, 
  

   involving 
  the 
  attack 
  of 
  slopes 
  at 
  their 
  base 
  by 
  arid 
  weathering, 
  

   and 
  the 
  removal 
  of 
  disintegrated 
  material 
  by 
  wind, 
  is 
  the 
  most 
  

   favourable 
  condition 
  for 
  the 
  development 
  and 
  maintenance 
  of 
  

   an 
  inselberg 
  landscape. 
  Existing 
  conditions 
  of 
  denudation 
  are 
  

   considered 
  to 
  be 
  unfavourable 
  to 
  inselberg 
  survival; 
  for 
  the 
  

   peaks 
  appear 
  to 
  be 
  worn 
  down 
  by 
  the 
  removal 
  of 
  superficial 
  

   layers 
  by 
  exfoliation 
  more 
  rapidly 
  than 
  the 
  surface 
  of 
  the 
  plateau 
  

   is 
  lowered. 
  

  

  2. 
  ' 
  The 
  Inferior 
  Oolite 
  and 
  Contiguous 
  Deposits 
  of 
  the 
  Crew- 
  

   kerne 
  District 
  (Somerset).' 
  By 
  Linsdall 
  Richardson, 
  F.R.IS.E., 
  

   F.G.S. 
  

  

  November 
  7th. 
  — 
  Dr. 
  Alfred 
  Harker, 
  F.R.S., 
  President, 
  

   in 
  the 
  Chair. 
  

  

  A 
  Lecture 
  on 
  'The 
  Nimrud 
  Crater 
  in 
  Turkish 
  Armenia' 
  

   was 
  delivered 
  by 
  Felix 
  Oswald, 
  B.A., 
  D.Sc, 
  F.G-.S. 
  

  

  The 
  Nimrud 
  volcano, 
  one 
  of 
  the 
  largest 
  volcanic 
  craters 
  in 
  the 
  

   world, 
  is 
  situated 
  on 
  the 
  western 
  shore 
  of 
  Lake 
  Van, 
  and 
  was 
  

   surveyed 
  and 
  investigated 
  geologically 
  for 
  the 
  first 
  time 
  by 
  the 
  

   speaker 
  in 
  1898. 
  The 
  Avestern 
  half 
  of 
  the 
  crater 
  is 
  occupied 
  by 
  a 
  

   deep 
  lake 
  of 
  fresh 
  water, 
  while 
  the 
  eastern 
  half 
  is 
  composed 
  of 
  

   recent 
  augite-rhyolites, 
  partly 
  cloaked 
  in 
  white 
  volcanic 
  ash. 
  The 
  

   crater- 
  wall 
  is 
  highest 
  on 
  the 
  north 
  (9903 
  feet), 
  rising 
  in 
  abrupt 
  

   precipices 
  over 
  2000 
  feet 
  above 
  the 
  lake 
  (7653 
  feet). 
  The 
  southern 
  

   wall 
  is 
  also 
  precipitous, 
  but 
  only 
  reaches 
  the 
  height 
  of 
  9434 
  feet 
  

   (the 
  south-eastern 
  part). 
  A 
  large 
  slice 
  of 
  the 
  crater- 
  wall 
  has 
  

   slipped 
  down 
  on 
  the 
  south-west, 
  so 
  as 
  to 
  form 
  a 
  narrow 
  shelf, 
  

   800 
  feet 
  above 
  the 
  lake. 
  The 
  crater 
  is 
  nearly 
  circular, 
  8405 
  yards 
  

   from 
  west-south-west 
  to 
  east-north-east, 
  while 
  the 
  transverse 
  axis 
  

   is 
  7905 
  yards. 
  The 
  lowest 
  points 
  lie 
  on 
  the 
  long 
  axis, 
  reaching 
  

   only 
  8139 
  feet 
  on 
  the 
  western, 
  and 
  8148 
  feet 
  on 
  the 
  eastern 
  rim. 
  

  

  The 
  crater- 
  wall 
  has 
  an 
  external 
  slope 
  of 
  33° 
  on 
  the 
  south 
  and 
  

   east, 
  where 
  it 
  consists 
  exclusively 
  of 
  overlapping 
  lenticular 
  flows 
  of 
  

   augite-rhyolite 
  and 
  obsidian. 
  On 
  the 
  south-west, 
  west, 
  north-west, 
  

   and 
  north 
  these 
  are 
  capped 
  by 
  thin 
  sheets 
  of 
  cindery 
  basalt 
  which 
  

   must 
  have 
  possessed 
  great 
  fluidity, 
  extending 
  for 
  many 
  miles 
  to 
  

   form 
  Avide 
  plains 
  of 
  gentle 
  slope 
  and 
  great 
  fertility 
  down 
  to 
  Lake 
  

   Van 
  on 
  the 
  east 
  and 
  into 
  the 
  Plain 
  of 
  Mush 
  on 
  the 
  Avest. 
  These 
  

   basalt-noAvs 
  dammed 
  up 
  the 
  north-east 
  to 
  south-west 
  A-alley 
  between 
  

  

  