﻿112 
  GEORGE 
  MAW'S 
  NOTES 
  ON 
  A 
  JOURNEY 
  

  

  the 
  salt-rock 
  near 
  the 
  fifth 
  caravansary, 
  bright 
  red 
  and 
  green 
  marls 
  

   are 
  exposed 
  in 
  the 
  banks 
  of 
  the 
  Oued 
  Melh, 
  dipping 
  south 
  at 
  ars 
  

   angle 
  of 
  35°. 
  These 
  bright-coloured 
  marls 
  appear 
  to 
  overlie 
  the 
  

   grey 
  saliferous 
  marls 
  of 
  the 
  salt-mountain, 
  and 
  form 
  the 
  base 
  of 
  the 
  

   series 
  of 
  the 
  Hauts 
  Plateaux. 
  Their 
  well-marked 
  mineral 
  character 
  

   enables 
  their 
  horizon 
  to 
  be 
  identified 
  in 
  several 
  localities 
  further 
  

   south. 
  The 
  Hauts 
  Plateaux 
  may 
  be 
  described 
  as 
  a 
  great 
  synclinal, 
  

   about 
  35 
  miles 
  across, 
  forming 
  an 
  open 
  tableland 
  of 
  an 
  average 
  

   height 
  of 
  3700 
  feet, 
  bounded 
  north 
  and 
  south 
  by 
  successive 
  series 
  of 
  

   terraced 
  escarpments. 
  The 
  beds 
  are 
  probably 
  of 
  Lower 
  Cretaceous 
  

   age, 
  and 
  apparently 
  a 
  repetition 
  of 
  those 
  of 
  the 
  Tell 
  Plateau, 
  consisting 
  

   of 
  grey 
  gypseous 
  marls 
  alternating 
  with 
  well-defined 
  courses 
  of 
  hard 
  

   fine-grained 
  argillaceous 
  and 
  calcareous 
  stone. 
  The 
  town 
  and 
  fortress 
  

   of 
  Djelfa 
  is 
  situated 
  near 
  the 
  centre 
  of 
  this 
  tableland, 
  at 
  a 
  height 
  

   of 
  3600 
  feet 
  ; 
  seven 
  miles 
  further 
  south 
  the 
  road 
  attains 
  its 
  highest 
  

   point, 
  at 
  a 
  height 
  of 
  a 
  little 
  over 
  4000 
  feet, 
  which, 
  however, 
  is 
  not 
  

   the 
  actual 
  summit, 
  as 
  higher 
  terraces 
  both 
  right 
  and 
  left 
  surmount 
  

   the 
  main 
  level 
  of 
  the 
  plateau, 
  and 
  probably 
  attain 
  a 
  level 
  of 
  about 
  

   4700 
  feet. 
  The 
  road 
  now 
  descends 
  the 
  southern 
  escarpment, 
  crossing 
  

   over 
  the 
  same 
  series 
  of 
  beds 
  dipping 
  north 
  that 
  were 
  passed 
  in 
  

   ascending 
  from 
  the 
  Kechers 
  de 
  Sel 
  to 
  Djelfa 
  ; 
  and 
  at 
  Ai'n-el-Ibel, 
  

   the 
  sixth 
  caravansary, 
  the 
  bright 
  red 
  and 
  green 
  marls 
  seen 
  near 
  

   the 
  salt 
  -mountain 
  are 
  again 
  exposed, 
  underlain 
  by 
  a 
  conglomerate 
  

   at 
  a 
  height 
  of 
  3300 
  feet. 
  Mr. 
  Tristram, 
  in 
  his 
  ' 
  Great 
  Sahara,' 
  

   records 
  the 
  occurrence 
  of 
  irregular 
  beds 
  of 
  lignite 
  in 
  this 
  neigh- 
  

   bourhood. 
  

  

  From 
  the 
  Hauts 
  Plateaux 
  to 
  L'Aghouat. 
  — 
  From 
  Ai'n-el-Ibel, 
  the 
  

   road 
  gradually 
  descends 
  over 
  an 
  undulating 
  plateau 
  of 
  red 
  and 
  yellow 
  

   sandstone, 
  probably 
  a 
  recurrence 
  of 
  the 
  sandstone 
  thrown 
  up 
  in 
  the 
  

   anticlinal 
  of 
  Guelt-el-Stel. 
  The 
  sandstone 
  south 
  of 
  Ai'n-el-Ibel 
  dips 
  

   21° 
  N.N.E., 
  and 
  further 
  south 
  gradually 
  decreases 
  in 
  inclination 
  till 
  

   within 
  a 
  mile 
  or 
  two 
  of 
  the 
  seventh 
  caravansary 
  of 
  Sidi 
  Makhelouf, 
  

   where 
  level 
  strata 
  of 
  red 
  sandstone, 
  forming 
  apparently 
  the 
  crown 
  of 
  

   the 
  low 
  anticlinal 
  are 
  reached 
  ; 
  these 
  are 
  the 
  lowest 
  beds 
  exposed 
  in 
  

   this 
  part 
  of 
  the 
  section. 
  At 
  the 
  caravansary 
  of 
  Sidi 
  Makhelouf, 
  

   2725 
  feet 
  above 
  the 
  sea, 
  the 
  sandstone 
  on 
  the 
  south 
  side 
  of 
  the 
  an- 
  

   ticlinal 
  commences 
  to 
  dip 
  S.S.W. 
  at 
  an 
  angle 
  of 
  from 
  10° 
  to 
  15°. 
  At 
  

   this 
  point 
  the 
  open 
  plateau 
  merges 
  into 
  a 
  valley 
  shut 
  in 
  by 
  ranges 
  

   of 
  the 
  beds 
  overlying 
  the 
  sandstone. 
  These 
  present 
  scarped 
  faces 
  on 
  

   either 
  side 
  of 
  the 
  gradually 
  narrowing 
  strath. 
  Between 
  Sidi 
  Makh- 
  

   elouf 
  and 
  Metlili, 
  at 
  a 
  height 
  of 
  2700 
  feet, 
  several 
  low 
  sandstone 
  

   hills 
  (Fig. 
  1) 
  rise 
  out 
  of 
  the 
  valley, 
  and 
  are 
  remarkable 
  for 
  their 
  

   perfectly 
  fiat 
  tops 
  at 
  a 
  uniform 
  level 
  independent 
  of 
  their 
  stratifica- 
  

   tion, 
  which 
  inclines 
  at 
  an 
  angle 
  of 
  15°. 
  I 
  can 
  only 
  account 
  for 
  their 
  

   contour 
  by 
  marine 
  denudation. 
  Here 
  also 
  the 
  fundamental 
  sand- 
  

   stone 
  begins 
  to 
  be 
  shrouded 
  over 
  by 
  grey 
  loam, 
  which 
  is 
  continuous 
  

   with 
  the 
  grey 
  loam 
  covering 
  the 
  open 
  Sahara 
  plain 
  further 
  south 
  ; 
  

   it 
  is 
  noticeable 
  that 
  this 
  superficial 
  deposit 
  sets 
  in 
  at 
  exactly 
  the 
  

   height 
  at 
  which 
  it 
  occurs 
  north 
  of 
  the 
  Hauts 
  Plateaux, 
  near 
  the 
  

   Itochers 
  de 
  Sel, 
  and 
  at 
  the 
  height 
  at 
  which 
  the 
  isolated 
  range 
  of 
  

  

  