The Atlas Range.—Commencing at Cape Guer, on the Atlantic sea-board, the range, which at a little distance has the aspect of a single ridge, averages at its western extremity from 4,000 to 5,000 feet in height, from which it slightly falls off in height for a few miles, and then gradually increases in height as it recedes from the coast. In the eastern part of the province of Haha the summits probably attain to a height of about 10,000 feet. At a point about 60 miles from the sea there is a comparatively deep breach in the range, through which runs the main road to Tarudant. Eastward of that pass the projecting summits appear to lie between 11,000 and 11,500 feet above the sea to a distance from the coast of about 100 miles, and about SW. of the city of Marocco, where a second depression occurs, affording a pass to the south, at an altitude of about 7,000 feet. Immediately east of this, and due south of the city of Marocco, the range for 30 miles in length presents a long unbroken ridge, 12,000 feet in height, on which are deposited a few isolated crags and peaks rising from 500 to 800 feet above the general level; and it is doubtful whether this part of the chain attains an extreme height of 13,000 feet. Still farther east the ridge-like character is lost, the range becoming broken up into a series of less continuous peaks (including Miltsin, estimated by Lieut. Washington to be 11,400 feet in altitude, and supposed by him to be the highest point in the chain) of diminished height: beyond this, eastward, little or nothing is known either of the altitude or character of the range, excepting that it trends NE. by E. towards the southern borders of Algeria on the Sahara.
Rohlfs, in his journal of his overland journey from Marocco to Tripoli, speaks of mountains to the east of Marocco being covered with perpetual snow; but this is a character which has been erroneously attributed to the Maroccan section of the Atlas range. When we arrived at Marocco 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 7,000 or 8,000 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 Marocco.
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 were 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 or more 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 2,000 to 3,000 feet above the plain, and 4,000 to 5,000 feet above the sea-level. This is intersected by occasional 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 escarpment 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 Marocco, the further details of which it will be convenient to consider under the following heads:—
(a) Surface Deposits and Boulder Beds.
(b) Moraines of the higher valleys.
(c) Stratified Red Sandstone and Limestone Series.
(d) Grey Shales.
(e) Metamorphic Rocks.
(f) Porphyrites.