462 APPENDIX H. 



and tlie main ridge of the Atlas. The edge of this plateau 

 facing the plain is for some distance an escarpment, exposing 

 stratified beds of limestone containing bands of chalcedonic 

 concretions, underlain by grey and puce-coloured marls. As 

 this plateau is crossed from north to south towards the Atlas 

 ridge, its central line would represent a synclinal, from which 

 the beds rise northwards towards the plain and southwards 

 towards the Atlas ; but it is locally broken and contorted, and 

 near Tasseremout the limestone beds stand up nearly on end. 

 South of the synclinal, i.e. between the centre of the irregular 

 plateau and the Atlas, great deposits of red sandstone and dark- 

 red conglomerate, interstratified with cream-coloured shelly 

 limestone, occur, which appear to be inferior members of the 

 series of limestones and marls exposed in the escarpment facing 

 the plain. Lieut. Washington, who ascended Miltsin to a height 

 of 6,400 feet, describes hard red sandstone with an east and 

 west strike dipping 10° south, as occurring at this elevation, 

 which is nearly 2,000 feet higher than we observed the Red 

 Sandstone series in the province of Reraya farther west, and 

 also both in his approach and descent from Miltsin of ranges of 

 limestone running NE. and SW. dipping 70° SE. with abrupt 

 sterile sandstone mountains rising above them. From the few 

 obscure fossils, including an Ostrea, I was able to collect from 

 the limestone bands, Mr. Etheridge considers that they are of 

 Cretaceous age. They are, like the beds of the plain, remark- 

 able for containing great deposits of chalcedonic concretions ; 

 but the latter may possibly be of more recent age. They rest 

 unconformably on the upturned edges of grey shaly beds, and 

 extend also over the porphyries that form the great mass of the 

 Atlas chain. They appear to have been deposited subsequently 

 to the porphyry ridge assuming its present hill-and-valley con- 

 tour, as little isolated fragments are seen clinging to the sides of' 

 a narrow ravine leading out of the valley we ascended through 

 the province of Eeraya to the Atlas. Their relation to the few 

 exposures of stratified beds in the plain is somewhat uncertain, 

 as no fossils were obtained in the latter, and there are no direct 

 connecting links; but, judging from petrological similarity, and 

 from the fact that Neocomian fossils occur in exposed beds on 

 the coast cliffs, and Cretaceous fossils in the beds forming the 

 crest of the plateau, it seems possible that an unbroken series 



