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| Keywords: The Quarterly journal of the Geological Society of London (12733842793).jpg PROM ALGIERS TO THE SAHARA 117 <br> Hemiaster or Penaster resembling Penaster Fournelli from the Hip- <br> purite limestone Brissus Avicula Inoceramus Lucina Cardium <br> Area Byssoarca Cardita Cyrena Cwullcea Clavatula c These <br> stand out as bosses from the matrix with a weathered black surface <br> and look like blotches of black mud ; the colour is only skin-deep <br> the mass of the nodules being of a pale grey They are excessively <br> hard and diffictilt to break and probably consist of ferruginous chert <br> The view from the summit of the escarpment is very singular <br> To the south the eye ranges over the great plain interrupted only <br> by the rocky ridge of L'Aghouat ; looking north a gentle dip-slope <br> descends to the flat valley about a mile wide bounded on the opposite <br> side by a complementary dip-slope with a repetition in reverse of the <br> beds seen in ascending the first escarpment The second ridge is <br> soon crossed ; and on descending its escarpment facing north another <br> flat valley about a mile wide is reached bounded on its opposite side <br> by an escarpment facing S E The view from the summits of these <br> ridges presents a series of ranges running N E by S W Fig 2 nearly <br> buried by a Posttertiary deposit of grey loam forming flat valleys <br> about a mile wide each alternate valley occurring between dip-slopes <br> and in the centre of a denuded anticlinal suggesting to the eye the <br> levelling up by a recent deposit of a series of hills and valleys that <br> had originally been of greater height and depth The level valley- <br> bottoms of loam are obviously an inland extension of the plain and <br> were deposited when the Sahara sea ran up as fjords between the <br> promontories of older land that branched out from the isolated land <br> of Algeria <br> Lignite occurs in several localities N of L'Aghouat viz in the <br> Djebel Amour at Kusra and at Berich also at El Kheicha on the banks <br> of the Oued M'Zi a branch of the L'Aghouat river where it is a <br> metre thick and overlain by black rock ; but I had not an opportu- <br> nity of seeing it in situ Fossil plants are said to occur a day's <br> iourney N W of L'Aghouat and are probably associated with the <br> lignite formation The only locality where the lignite has been <br> observed in situ by a geologist is that noticed by Mr Tristram at <br> Ai'n-el-Ibel where it occurs near the horizon of the band of bright <br> red and green marls exposed in several localities on my line of section <br> and probably a little above the horizon of the salt deposit of the <br> Eochers de Sel <br> Of the occurrence of other minerals the following localities were <br> named to me at L'Aghouat ” <br> Nitrate of potash is found near Touat manganese at Outhed el <br> Abiod lead at Oued Sidi Bilgassem and copper at Berich ; but I <br> could not ascertain the mineralogical conditions under which the lead <br> and copper occur <br> My return journey from L'Aghouat following the same line of <br> route enabled me to check and correct the altitudes and fill in addi- <br> tional details in the section <br> Stratigraphical Summary ” In conclusion I will give a general <br> summary in stratigraphical sequence of the formations and of the <br> successive changes of level and contour of the district comprised in 35765986 110599 51125 Page 116 Text v 30 http //www biodiversitylibrary org/page/35765986 1874 Geological Society of London NameFound Avicula NameConfirmed Avicula EOLID 10721231 NameBankID 4633901 NameFound Brissus NameConfirmed Brissus EOLID 73050 NameBankID 2765370 NameFound Byssoarca NameConfirmed Byssoarca NameBankID 4097488 NameFound Cardita NameConfirmed Cardita EOLID 57589 NameBankID 2693146 NameFound Cardium NameConfirmed Cardium EOLID 50301 NameBankID 2693257 NameFound Clavatula NameConfirmed Clavatula EOLID 2988881 NameBankID 4118258 NameFound Cyrena NameConfirmed Cyrena EOLID 4757476 NameBankID 4134596 NameFound Hemiaster NameConfirmed Hemiaster EOLID 599041 NameBankID 2765357 NameFound Inoceramus NameConfirmed Inoceramus EOLID 4747366 NameBankID 4205663 NameFound Penaster NameConfirmed Penaster NameBankID 4287636 Biodiversity Heritage Library The Quarterly journal of the Geological Society of London v 30 1874 Geology Periodicals Smithsonian Libraries bhl page 35765986 dc identifier http //biodiversitylibrary org/page/35765986 smithsonian libraries Information field Flickr posted date ISOdate 2014-02-24 Check categories 2015 August 26 CC-BY-2 0 BioDivLibrary https //flickr com/photos/61021753 N02/12733842793 2015-08-26 19 58 28 cc-by-2 0 PD-old-70-1923 The Quarterly journal of the Geological Society of London 1874 Photos uploaded from Flickr by Fæ using a script | ||||
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