﻿Vol. 
  53.] 
  GEOLOGY 
  OF 
  PART 
  OF 
  THE 
  NUBIAN 
  DESERT. 
  361 
  

  

  at 
  the 
  base 
  of 
  the 
  cliffs 
  by 
  the 
  river. 
  This 
  lowest 
  part 
  of 
  the 
  great 
  

   plain 
  of 
  Nubian 
  Sandstone 
  is 
  at 
  Korosko 
  about 
  380 
  feet 
  above 
  the 
  

   Mediterranean, 
  and 
  it 
  rises 
  to 
  about 
  1700 
  feet 
  at 
  the 
  foot 
  of 
  Jebel 
  

   Raft 
  in 
  the 
  eastern 
  desert, 
  while 
  in 
  the 
  western 
  desert 
  much 
  lower 
  

   altitudes 
  are 
  met 
  with, 
  and 
  the 
  plateau 
  100 
  miles 
  south 
  of 
  the 
  oases 
  

   of 
  Kharga 
  and 
  of 
  Dakhla 
  has 
  only 
  attained 
  an 
  altitude 
  of 
  500 
  and 
  

   800 
  feet 
  respectively. 
  

  

  The 
  caravan 
  road 
  from 
  Korosko 
  to 
  Abu 
  Hamed, 
  which 
  passes 
  by 
  

   the 
  Murrat 
  Wells, 
  ascends 
  for 
  the 
  first 
  50 
  miles 
  through 
  the 
  sand- 
  

   stone 
  plateau 
  and 
  finally 
  comes 
  out 
  upon 
  the 
  high 
  plateau, 
  passing 
  

   through 
  a 
  gap 
  in 
  the 
  escarpment 
  which 
  overlooks 
  the 
  former 
  plateau 
  

   at 
  the 
  Bab 
  el 
  Korosko. 
  This 
  is 
  approximately 
  1600 
  feet 
  above 
  sea- 
  

   level. 
  The 
  higher 
  plateau 
  is 
  a 
  gently 
  undulating 
  plain 
  with 
  isolated 
  

   hills 
  of 
  sandstone, 
  and 
  it 
  drains 
  to 
  the 
  east 
  into 
  the 
  Wadi 
  Kabkaba 
  ; 
  

   this 
  in 
  its 
  turn 
  joins 
  the 
  Wadi 
  Allaki, 
  which 
  meets 
  the 
  Nile 
  at 
  

   Siala. 
  

  

  To 
  the 
  south 
  and 
  east 
  this 
  plain 
  is 
  bounded 
  by 
  hills 
  of 
  crys- 
  

   talline 
  rocks, 
  against 
  the 
  flanks 
  of 
  which 
  the 
  sandstone 
  has 
  been 
  

   horizontally 
  laid 
  down. 
  

  

  (2) 
  The 
  Crystalline 
  Rocks 
  (massive 
  and 
  schistose) 
  . 
  

  

  Coming 
  from 
  Korosko 
  to 
  the 
  Murrat 
  Wells 
  the 
  crystalline 
  rocks 
  

   are 
  first 
  met 
  with 
  in 
  the 
  Wadi 
  Mogharin 
  on 
  the 
  east 
  side 
  of 
  Jebel 
  

   Raft, 
  which 
  seems 
  to 
  consist 
  mainly 
  of 
  granite, 
  diorite, 
  etc., 
  while 
  

   the 
  Nubian 
  Sandstone 
  is 
  laid 
  down 
  horizontally 
  on 
  the 
  flanks 
  of 
  

   these 
  on 
  the 
  north 
  side. 
  It 
  is 
  possible 
  that 
  Jebel 
  Khatab 
  el 
  

   Atshan 
  may 
  be 
  an 
  outlier 
  of 
  these 
  crystalline 
  rocks; 
  this 
  is 
  

   inferred 
  from 
  the 
  appearance 
  of 
  its 
  black 
  summit 
  rising 
  above 
  the 
  

   sandstone 
  which 
  forms 
  its 
  lower 
  slopes, 
  and 
  also 
  from 
  the 
  statement 
  

   of 
  the 
  Arabs 
  that 
  there 
  is 
  a 
  rainwater-reservoir 
  in 
  this 
  hill. 
  On 
  the 
  

   south 
  and 
  east 
  side 
  of 
  Jebel 
  Raft 
  there 
  is 
  an 
  area 
  of 
  low 
  ground 
  

   occupied 
  by 
  schists, 
  dipping 
  at 
  various 
  angles 
  from 
  40° 
  to 
  vertical, 
  

   and 
  much 
  intersected 
  by 
  dykes. 
  Those 
  south 
  of 
  Jebel 
  Raft 
  have 
  a 
  

   direction 
  of 
  strike 
  which 
  varies 
  a 
  few 
  degrees 
  on 
  either 
  side 
  of 
  east 
  

   and 
  west, 
  while 
  those 
  to 
  the 
  east 
  of 
  this 
  hill 
  and 
  in 
  the 
  neighbourhood 
  

   of 
  Jebel 
  Banat 
  Raft 
  and 
  Kageritbar 
  have 
  a 
  distinct 
  north-and-south 
  

   strike, 
  which 
  is 
  continued 
  until 
  the 
  massive 
  crystalline 
  rocks 
  of 
  

   Tilat 
  Abda 
  are 
  reached. 
  

  

  The 
  schists 
  occur 
  on 
  the 
  south 
  side 
  of 
  Jebel 
  Raft 
  and 
  at 
  a 
  short 
  

   distance 
  to 
  the 
  north 
  of 
  Murrat 
  Wells, 
  but 
  are 
  seen 
  in 
  their 
  greatest 
  

   development 
  between 
  this 
  place 
  and 
  the 
  west 
  side 
  of 
  Jebel 
  Raft. 
  

   Here, 
  in 
  the 
  Wadi 
  Om 
  Nabadi, 
  are 
  the 
  ancient 
  gold-workings 
  which 
  

   are 
  indicated 
  by 
  Linant 
  de 
  Bellefonds 
  in 
  his 
  map 
  of 
  the 
  Etbai. 
  The 
  

   valley 
  is 
  crowded 
  with 
  ruins 
  of 
  small 
  circular 
  huts, 
  about 
  6| 
  feet 
  

   in 
  diameter, 
  built 
  of 
  loose 
  rubble-stone, 
  which 
  were 
  the 
  dwellings 
  

   of 
  the 
  workmen, 
  and 
  the 
  lower 
  part 
  of 
  a 
  granite 
  hand-mill 
  lay 
  near, 
  

   but 
  this 
  probably 
  was 
  for 
  grinding 
  corn 
  rather 
  than 
  for 
  crushing 
  the 
  

   rock, 
  for 
  that 
  was 
  done 
  with 
  rubbing-stones 
  about 
  3 
  to 
  4 
  pounds 
  in 
  

   weight. 
  1 
  had 
  not 
  time 
  to 
  make 
  a 
  very 
  detailed 
  examination 
  of 
  

  

  