GEOLOGY OF MAROCCO AND GEEAT ATLAS. 453 



perforations. The depressiong are occupied by a very porous 

 conglomerate, passing into a calcareous sandstone used for 

 building. This conglomerate contains an abundance of Helix 

 vermiculata, a species living in the country, and also found in 

 the calcareous sands which are supposed to be of post-PLiocene 

 age. The plain of Doukala {Ducaila of Washington), at a level 

 of about 140 feet above the sea, is covered with these sands. 

 At Sidi Ammer an escarpment was observed, the base of which 

 consisted of clay and red ferruginous marls, containing a stratum 

 formed for the most part of oysters, in which also Teredina 

 personata occurred, supposed by M, Nyst to belong to the 

 Eocene formation ; succeeded by another foasiliferous bed con- 

 taining 



Balanus sulcatus, 



Pecten Beudanti, 



Area, 



Buccinum prismaticum, and 



Conus, 



supposed by M. Nyst to be Miocene, the upper part of the 

 escarpment resembling the beds of later age before described. 



An examination of the higher points of the western coast 

 near SaiB, and at Azfi in the province of Abda, near Mazagan, 

 tended to establish the fact of the occurrence of Pliocene beds 

 in the district. 



At Gape Safli, 180 metres in altitude, a reddish calcareous 

 sand was met with abounding in Cyclostoiiia, Cylindrellas, and 

 a species of Ildix differing from that at Mazagan ; and at 

 other points, including the hill of Aher and at Sidi Bousid, 

 white marls and sands associated with calcareous sandstones 

 were met with analogous to the supposed quaternary beds in 

 the neighbourhood of Mazagan. 



The only other point in the geology of the coast-line I have 

 to refer to is the great mass of blown sand surrounding Mogador, 

 presenting a weird expanse of sea-like waves of sand, on a scale 

 vastly greater than anything of the kind on our own coast, 

 mimetic of mountain-chains and bold escarpments in miniature, 

 differing only from true hill-and-valley structure in the absence 

 of continuous valley-lines, the hollows being completely sur- 

 rounded by higher ground. Many of the ranges of sand are 

 from 80 to 100 feet in height, and their perfectly straight 



