﻿FROM 
  ALGIERS 
  TO 
  THE 
  SAHARA. 
  

  

  113 
  

  

  Fig. 
  1. 
  — 
  Flat-topped 
  Sandstone 
  Hills 
  between 
  Sidi 
  Mal-helotif 
  and 
  

   Metlili 
  (2700 
  feet 
  above 
  sea-level.) 
  

  

  Grey 
  loam 
  in 
  bottom 
  of 
  valley. 
  

  

  sand-dunes 
  occurs 
  in 
  the 
  same 
  locality. 
  I 
  shall 
  further 
  on 
  refer 
  to 
  

   these 
  evidences 
  of 
  the 
  former 
  extent 
  of 
  the 
  Sahara 
  submergence. 
  

  

  At 
  Metlili 
  the 
  flat 
  valley 
  narrows 
  to 
  a 
  mile 
  and 
  a 
  half 
  in 
  width, 
  

   and 
  follows 
  a 
  direct 
  southwest 
  course. 
  It 
  is 
  bounded 
  by 
  symmetrical 
  

   escarpments 
  250 
  feet 
  high, 
  composed 
  of 
  gypseous 
  marls 
  interstra- 
  

   tified 
  and 
  capped 
  with 
  harder 
  strata, 
  the 
  irregular 
  denudation 
  of 
  

   which 
  has 
  resulted 
  in 
  a 
  singular 
  range 
  of 
  isolated 
  bosses 
  and 
  pinnacles 
  

   separated 
  by 
  little 
  lateral 
  ravines. 
  Near 
  Metlili, 
  bright 
  red 
  and 
  

   green 
  marls 
  similar 
  to 
  those 
  at 
  AYn-el-Ibel 
  and 
  those 
  near 
  the 
  

   Bochers 
  de 
  Sel 
  are 
  again 
  observed 
  in 
  the 
  bottom 
  of 
  the 
  valley 
  ; 
  so 
  

   that 
  the 
  escarpments 
  bounding 
  it 
  probably 
  correspond 
  with 
  the 
  beds 
  

   of 
  the 
  Hauts 
  Plateaux; 
  the 
  upper 
  part 
  may 
  be 
  on 
  a 
  higher 
  horizon. 
  

   The 
  road 
  here 
  follows 
  for 
  a 
  few 
  miles 
  the 
  line 
  of 
  strike, 
  but 
  on 
  

   turning 
  S.E. 
  gradually 
  passes 
  an 
  ascending 
  series 
  of 
  beds, 
  under 
  

   which 
  the 
  red 
  and 
  green 
  marls 
  are 
  lost 
  ; 
  and 
  turning 
  through 
  a 
  break 
  

   in 
  the 
  eastern 
  escarpment, 
  where 
  the 
  flat 
  valley 
  widens 
  out, 
  drifted 
  

   sand 
  and 
  sandhills 
  commence 
  ; 
  the 
  open 
  plain 
  is 
  now 
  approached, 
  into 
  

   which 
  the 
  cliff-like 
  escarpments 
  die 
  out 
  as 
  isolated 
  ridges 
  running 
  

   N.E. 
  and 
  S.W., 
  separated 
  by 
  flat-bottomed 
  valleys 
  about 
  a 
  mile 
  wide. 
  

   The 
  scene 
  is 
  most 
  singular, 
  and 
  at 
  once 
  suggests 
  to 
  the 
  eye 
  the 
  sub- 
  

   mergence 
  of 
  the 
  older 
  land 
  beneath 
  a 
  newer 
  deposit, 
  which 
  continues 
  

   as 
  a 
  level 
  plain 
  as 
  far 
  as 
  the 
  eye 
  can 
  reach. 
  Three 
  or 
  four 
  parallel 
  

   ridges, 
  separated 
  by 
  intervening 
  straths, 
  terminate 
  the 
  high 
  ground, 
  

   each 
  alternate 
  flat 
  occurring 
  between 
  dip 
  slopes 
  and 
  on 
  denuded 
  

   anticlinals 
  (Fig. 
  2) 
  ; 
  the 
  final 
  escarpment, 
  dipping 
  N\W. 
  at 
  an 
  angle 
  

   of 
  25°, 
  presents 
  a 
  cliff-like 
  amphitheatre 
  facing 
  the 
  great 
  plain 
  

   (Fig. 
  3). 
  Beyond 
  this, 
  at 
  a 
  distance 
  of 
  about 
  three 
  miles, 
  isolated 
  

   rocks 
  with 
  a 
  complementary 
  escarpment 
  facing 
  N.W. 
  rise 
  up 
  out 
  of 
  

   the 
  plain, 
  and 
  dip 
  away 
  S.E. 
  at 
  a 
  steep 
  angle 
  under 
  the 
  shroud 
  of 
  

   grey 
  loam 
  and 
  sandhills. 
  On 
  one 
  of 
  these 
  rocks 
  L'Aghouat> 
  the 
  most 
  

   southern 
  French 
  fortress 
  in 
  this 
  part 
  of 
  Algeria, 
  rises 
  up 
  from 
  an 
  

   oasis 
  amid 
  an 
  immense 
  grove 
  of 
  date-palms, 
  and 
  presents 
  a 
  pictu- 
  

   resque 
  association 
  of 
  Arab 
  mud 
  houses, 
  French 
  military 
  buildings, 
  

   and 
  a 
  new 
  mosque. 
  The 
  town 
  is 
  situated 
  at 
  a 
  height 
  of 
  2333 
  feet 
  

   above 
  the 
  sea. 
  The 
  great 
  altitude 
  at 
  which 
  the 
  sandhills 
  commence 
  

   in 
  its 
  neighbourhood, 
  was 
  a 
  fact 
  I 
  had 
  not 
  anticipated, 
  as 
  further 
  to 
  

   the 
  N.E., 
  south 
  of 
  Biskra, 
  the 
  desert 
  plain 
  is 
  on 
  the 
  level 
  of 
  the 
  sea, 
  

  

  