﻿122 
  GEORGE 
  MAW'S 
  NOTES 
  ON 
  A 
  JOURNEY 
  

  

  the 
  Sahara 
  submergence 
  ; 
  but 
  the 
  Great 
  Atlas 
  chain 
  to 
  the 
  N.W. 
  

   would 
  probably 
  have 
  partaken 
  of 
  the 
  general 
  depression, 
  and 
  the 
  

   comparatively 
  low 
  level 
  at 
  which 
  moraines 
  there 
  occur 
  would 
  have 
  

   been 
  brought 
  still 
  nearer 
  the 
  sea-level, 
  counterbalancing 
  the 
  effect 
  of 
  

   increased 
  refrigeration. 
  A 
  small 
  glacier 
  still 
  exists 
  at 
  a 
  height 
  of 
  

   between 
  8000 
  and 
  9000 
  feet 
  in 
  the 
  Sierra 
  Nevada 
  south 
  of 
  Granada, 
  

   in 
  latitude 
  37° 
  ; 
  and 
  supposing 
  the 
  Great 
  Atlas 
  had 
  partaken 
  of 
  the 
  

   elevation 
  of 
  3000 
  feet 
  assumed 
  by 
  Mr. 
  Dawkins 
  as 
  the 
  Postpliocene 
  

   height 
  of 
  the 
  present 
  Mediterranean 
  boundary, 
  a 
  corresponding 
  alti- 
  

   tude 
  of 
  the 
  Great 
  Atlas 
  of 
  from 
  15,000 
  to 
  16,000 
  feet 
  would 
  probably 
  

   have 
  afforded 
  sufficient 
  height 
  for 
  the 
  bearing 
  of 
  similar 
  small 
  glaciers 
  

   at 
  existing 
  temperatures. 
  The 
  high 
  land 
  of 
  Algeria 
  has 
  certainly 
  

   been 
  elevated 
  3000 
  feet 
  since 
  the 
  Sahara 
  submergence 
  ; 
  and 
  it 
  is 
  

   probable 
  that 
  its 
  maximum 
  elevation 
  may 
  have 
  reached 
  6000 
  feet 
  

   in 
  Postpliocene 
  times, 
  since 
  which 
  a 
  gradual 
  subsidence 
  of 
  3000 
  

   must 
  have 
  taken 
  place 
  and 
  appears 
  to 
  be 
  still 
  going 
  on. 
  

  

  EXPLANATION 
  OF 
  PLATE 
  XI. 
  

  

  Fig. 
  1. 
  Section 
  across 
  Algeria, 
  from 
  Algiers 
  to 
  L'Aghouat, 
  Sahara. 
  Vertical 
  

   scale 
  1 
  inch 
  to 
  9000 
  feet 
  ; 
  horizontal 
  scale 
  3& 
  inches 
  to 
  30 
  miles. 
  

   2. 
  Map 
  of 
  route 
  from 
  Algiers 
  to 
  L'Aghouat. 
  The 
  line 
  of 
  route 
  is 
  indi- 
  

   cated 
  by 
  a 
  dotted 
  line, 
  the 
  line 
  of 
  section 
  by 
  a 
  thick 
  black 
  line, 
  and 
  

   the 
  strike 
  of 
  the 
  beds 
  at 
  different 
  parts 
  by 
  fine 
  double 
  lines. 
  

  

  DlSCUSSIONa 
  

  

  Mr. 
  W. 
  Boyd 
  Dawkins 
  considered 
  an 
  elevation 
  of 
  from 
  2000 
  to 
  3000 
  

   feet 
  necessary 
  to 
  allow 
  of 
  that 
  migration 
  of 
  animals 
  through 
  Spain 
  and 
  

   Sicily, 
  to 
  and 
  from 
  Europe 
  and 
  Africa, 
  which 
  took 
  place 
  in 
  Pleisto- 
  

   cene 
  times; 
  and 
  this 
  view 
  appeared 
  to 
  be 
  confirmed 
  on 
  physical 
  

   grounds 
  by 
  Mr. 
  Maw. 
  He 
  believed 
  that 
  a 
  great 
  axis 
  of 
  disturbance 
  

   ran 
  east 
  and 
  west 
  along 
  the 
  course 
  of 
  the 
  Mediterranean 
  ; 
  and 
  to 
  

   this 
  the 
  strike 
  of 
  the 
  beds 
  observed 
  by 
  Mr. 
  Maw 
  was 
  parallel. 
  It 
  

   is 
  a 
  remarkable 
  fact 
  that 
  the 
  change 
  in 
  the 
  level 
  of 
  the 
  Sahara 
  

   observed 
  by 
  Mr. 
  Maw 
  should 
  be 
  the 
  same 
  as 
  that 
  which 
  has 
  taken 
  

   place 
  in 
  the 
  Mediterranean 
  area, 
  but 
  in 
  the 
  opposite 
  direction. 
  

   Probably 
  the 
  elevation 
  of 
  the 
  Sahara 
  was 
  coincident 
  with 
  the 
  

   depression 
  of 
  the 
  Mediterranean. 
  

  

  Mr. 
  Batterman 
  called 
  attention 
  to 
  the 
  excellent 
  drawing 
  of 
  a 
  

   desert 
  escarpment 
  exhibited 
  by 
  Mr. 
  Maw. 
  He 
  said 
  that 
  this 
  draw- 
  

   ing 
  perfectly 
  represented 
  what 
  is 
  to 
  be 
  seen 
  in 
  every 
  dry 
  desert 
  

   country, 
  like 
  the 
  north 
  of 
  Africa 
  or 
  Arabia. 
  In 
  the 
  latter 
  country 
  

   the 
  succession 
  of 
  the 
  beds 
  of 
  Neocomian 
  and 
  Tertiary 
  age 
  was 
  

   similar 
  to 
  that 
  observed 
  in 
  Algiers. 
  He 
  thought 
  that 
  the 
  disturb- 
  

   ances 
  attributed 
  by 
  Mr. 
  Maw 
  to 
  the 
  dissolving 
  out 
  of 
  salt, 
  were 
  in 
  

   reality 
  due 
  to 
  the 
  dissolving 
  of 
  gypsum. 
  

  

  Mr. 
  Davidson 
  remarked 
  that 
  thirty 
  years 
  ago 
  M. 
  de 
  Yerneuil 
  

   found 
  many 
  fossils 
  in 
  the 
  region 
  to 
  which 
  Mr. 
  Maw's 
  paper 
  related. 
  

   These 
  included 
  a 
  great 
  Ostrea, 
  Terebratulce^ 
  and 
  other 
  forms 
  which 
  

   were 
  both 
  Miocene 
  and 
  Pliocene. 
  

  

  