﻿FROM 
  ALGIERS 
  TO 
  THE 
  SAHARA. 
  109 
  

  

  Cyprina, 
  Area, 
  Pedunculitis, 
  and 
  several 
  species 
  of 
  Ostrea 
  and 
  

   Pecten. 
  

  

  The 
  calcareous 
  freestone 
  is 
  highly 
  ferruginous, 
  and 
  contains 
  

   deposits 
  of 
  hydrous 
  sesquioxide 
  of 
  iron, 
  undistinguishable 
  from 
  the 
  

   iron- 
  ores 
  of 
  the 
  Northamptonshire 
  Oolites. 
  

  

  After 
  the 
  Tertiary 
  escarpment 
  is 
  crossed 
  near 
  Berouagui'a, 
  at 
  a 
  

   height 
  of 
  4000 
  feet, 
  the 
  road 
  rapidly 
  descends 
  to 
  a 
  level 
  of 
  3100 
  

   feet, 
  and 
  for 
  a 
  few 
  hundred 
  yards 
  a 
  sharp 
  anticlinal 
  of 
  hard 
  grey 
  

   slaty 
  rock 
  similar 
  to 
  that 
  of 
  the 
  Atlas 
  is 
  passed 
  ; 
  from 
  this 
  point 
  

   to 
  near 
  Boghar 
  the 
  road, 
  at 
  a 
  level 
  of 
  from 
  3150 
  to 
  3600 
  feet, 
  

   passes 
  over 
  an 
  undulating 
  country, 
  the 
  higher 
  parts 
  of 
  which 
  are 
  

   crowned 
  with 
  forests 
  of 
  Pinus 
  halejpensis. 
  Overlying 
  the 
  anti- 
  

   clinal 
  above 
  Berouagu'ia, 
  beds 
  apparently 
  identical 
  with 
  those 
  in 
  

   the 
  southern 
  half 
  of 
  the 
  gorge 
  of 
  La 
  Chiffa 
  again 
  set 
  in 
  and 
  extend 
  

   without 
  interruption 
  to 
  the 
  southern 
  escarpment 
  of 
  the 
  Tell, 
  at 
  

   Boghar. 
  In 
  physical 
  aspect 
  they 
  resemble 
  our 
  Lower 
  Lias, 
  and 
  

   consist 
  of 
  dark 
  bluish 
  marls, 
  often 
  en 
  masse, 
  but 
  occasionally 
  in- 
  

   terstratified 
  with 
  well-defined 
  thin 
  courses 
  of 
  hard 
  calcareous 
  and 
  

   argillaceous 
  rock. 
  These 
  beds 
  are 
  highly 
  contorted, 
  and 
  present 
  

   a 
  succession 
  of 
  dips 
  both 
  north 
  and 
  south 
  at 
  high 
  angles, 
  occa- 
  

   sionally 
  vertical, 
  and 
  arranged 
  in 
  shortly 
  repeated 
  series 
  of 
  syn- 
  

   clinals 
  and 
  anticlinals, 
  the 
  valleys 
  nearly 
  always 
  occurring 
  on 
  

   anticlinals. 
  The 
  strike 
  of 
  these 
  contorted 
  beds 
  is 
  locally 
  variable, 
  

   but 
  maintains 
  a 
  general 
  east 
  and 
  west 
  direction. 
  I 
  obtained 
  no 
  

   fossils 
  between 
  Berouagui'a 
  and 
  Boghar 
  ; 
  but 
  at 
  Boukhari 
  (a 
  neigh- 
  

   bouring 
  village, 
  situated 
  on 
  an 
  outlying 
  spur 
  of 
  the 
  Tell 
  plateau), 
  

   I 
  collected 
  the 
  following 
  species 
  :— 
  Ostrea, 
  allied 
  to 
  O. 
  multicostata, 
  

   a 
  fragment 
  of 
  an 
  Ostrea 
  allied 
  to 
  O. 
  cyathula, 
  Ostrea 
  allied 
  to 
  

   O. 
  callifera, 
  Pullastra 
  (sp.), 
  Pleurotomaria 
  (sp.), 
  and 
  several 
  examples 
  

   of 
  Pecten 
  which 
  are 
  supposed 
  by 
  Mr. 
  Etheridge 
  to 
  be 
  of 
  Miocene 
  

   age. 
  In 
  the 
  museum 
  at 
  Algiers, 
  there 
  is 
  a 
  small 
  series 
  of 
  fossils 
  

   from 
  the 
  neighbourhood 
  of 
  Boghar, 
  which 
  I 
  have 
  had 
  photographed. 
  

   It 
  includes 
  some 
  large 
  Ostrece, 
  which 
  Mr. 
  Etheridge 
  and 
  Professor 
  

   Phillips 
  think 
  may 
  be 
  of 
  Tertiary 
  age, 
  but 
  possibly 
  Cretaceous 
  ; 
  

   there 
  are 
  also 
  some 
  Lower-Cretaceous 
  fossils 
  from 
  the 
  same 
  locality, 
  

   viz. 
  a 
  Turrilites, 
  an 
  Ammonites 
  allied 
  to 
  A. 
  Deshayesii, 
  a 
  Trigonia, 
  

   an 
  Inoceramus, 
  and 
  an 
  Astarte; 
  also 
  an 
  Urchin, 
  of 
  the 
  genus 
  

   Micraster 
  or 
  Toxaster. 
  This 
  series 
  is 
  important, 
  as 
  affording 
  a 
  key 
  

   to 
  the 
  age 
  of 
  the 
  great 
  mass 
  of 
  stratified 
  beds 
  of 
  the 
  Tell 
  plateau, 
  

   and 
  tallies 
  in 
  age 
  with 
  some 
  Lower- 
  Cretaceous 
  fossils 
  of 
  other 
  

   species 
  obtained 
  by 
  Mr. 
  Tristram 
  in 
  1861 
  on 
  the 
  northern 
  escarp- 
  

   ment 
  of 
  the 
  Hauts 
  Plateaux. 
  The 
  beds 
  at 
  Boukhari 
  are 
  apparently 
  

   on 
  the 
  same 
  horizon 
  as 
  the 
  Boghar 
  escarpment 
  ; 
  and 
  I 
  am 
  inclined 
  

   to 
  think 
  that 
  the 
  rather 
  imperfect 
  series 
  of 
  fossils 
  I 
  obtained 
  from 
  

   the 
  neighbourhood 
  of 
  Boukhari 
  may 
  be 
  of 
  Cretaceous 
  age, 
  especially 
  

   as 
  their 
  general 
  facies 
  resembles 
  the 
  fossils 
  I 
  collected 
  from 
  the 
  

   Neocomian 
  beds 
  at 
  Saffe, 
  on 
  the 
  coast 
  of 
  Marocco. 
  

  

  Between 
  Boghar 
  and 
  Boukhari 
  the 
  road 
  descends 
  the 
  southern 
  

   escarpment 
  of 
  the 
  Tell 
  plateau 
  to 
  the 
  valley 
  of 
  the 
  Cheliff 
  and 
  the 
  

   great 
  low-level 
  plain 
  of 
  the 
  northern 
  Sahara, 
  situated 
  at 
  a 
  height 
  of 
  

  

  Q. 
  J. 
  G. 
  S. 
  No. 
  118. 
  k 
  

  

  