1872.] MAW PLAIN OF MOROCCO. 91 



feet in height, on which are disposed a few isolated crags and peaks 

 rising from 500 to 800 feet above the general level ; and it is doubt- 

 ful whether any part of the chain attains an extreme height of 

 13,000 feet (fig. 2). Still further east the ridge-like character is lost, 

 the range becoming broken up into a series of less-continuous peaks 

 (including Miltsin) of diminished height : beyond this, eastward, 

 little or nothing is known either of the altitude or character of the 

 range, excepting that it trends jS'.E. by E. towards the southern 

 borders of Algeria on the Sahara. 



Rolfe, in his journal of his overland journey from Morocco to 

 Tunis, speaks of mountains to the east of Morocco being covered with 

 perjietucd snow; but this is a character which has been erroneously 

 attributed to the Moroccan section of the Atlas range. "When we 

 arrived at Morocco in the first week of May, the snow was limited 

 to steep gullies and drifts — all the exposed parts, including the very 

 summit, being entirely bare. There were, however, frequent storms, 

 which intermittently covered the range down to 7000 or 8000 feet ; 

 but it is certain that these occasional falls would be rapidly cleared 

 off by the summer heat ; and we came to the conclusion that there 

 was nothing like perpetual snow on any portion of the chain we 

 visited, included in the section (apparently the highest part) lying 

 due south of the city of Morocco. 



As seen from the city, the great ridge appears to rise abruptly 

 from the plain some 25 miles off ; and so deceptive is the distance, 

 that it looks as though it was a direct ascent from the plain to the 

 snow-capped summit, even too steep to scale ; but in reality this 

 wall-like ridge represents a horizontal distance of 15 miles from the 

 foot to the summit. As we approached it, an irregular plateau four 

 or five miles wide was seen to form a sort of foreground to the great 

 mass of the chain, from 2000 to 3000 feet above the plain, and 

 4000 to 5000 feet above the sea-level. This is intersected by oc- 

 casional narrow ravines, which wind up to the crest of the ridge ; 

 and its face, fronting the plain, is for the most part exposed as an es- 

 carpment of red sandstone and limestone beds dipping away from 

 the plain, and again rising from a synclinal against the crystalline 

 porphyrites of the centre of the ridge, and unconformably overlying 

 nearly vertical grey shaly beds with a strike ranging with the general 

 trend of the Atlas range. Against the plateau-escarpment rest 

 enormous mounds of boulders spreading down to the level plain. 



These, then, are the general features of the chain of the Atlas and 

 plain of Morocco, the further details of which it will be convenient 

 to consider under the following heads: — 



(a) Surface-deposits and Boulder-beds. 



(h) Moraines of the higher valleys. 



(c) Stratified Eed-Sandstone and Limestone Series. 



{d) Grey Shales. 



(e) Metamorphic Rocks. 



(/) Porphyrites. 



(g) Eruptive Basalts. 



(a) Surface-deposits and Boulder-beds. — 'Next to the Tufa-crust 



