wide, is very fertile, especially the black clay lands called tars; further from the sea one passes gradually to the steppe. Then cultivation begins again at the foot of the Atlas, thanks to irriga tion. The rivers of the meseta run in a small number of ravines deeply dissecting the plateau. The Bu-Regrag, reaching the sea at Rabat is unimportant. The Umm er Rbiea, on the contrary, is the largest river of north-west Africa ; rising in mid-Atlas, it runs at first in a deep narrow tectonic valley as far as Khenifra, then crosses the plain of Tadla, receives the Wad-el-Abiad and the Tessaut, both rising in the high Atlas, encases itself deeply from Mechra-ben-Abbu to Bu-Lauan and reaches the sea at Azimur ; its average discharge is 6o cubic metres, minimum 35 cubic metres. The much smaller Tensift drains the plain of Marrakesh; its left bank affluents, the Wad Rdat, Wad Reraia, Wad Urika and Wad Nfys, bring it the drainage of the high Atlas. The coast of the meseta is extremely monotonous and even, and is, in general, edged with dunes with several shallow lagoons. The surf is very strong, and before the French protectorate there were only open roadsteads.
(3) The Moroccan Atlas (see ATLAS) is bounded on the north by the plains and plateaux of the Atlantic slope and by the corri dor of Taza; on the south it slopes down towards the great furrow of the Wad Draca, beyond which stretch the platforms of the Sahara. It is usual to distinguish three chains of the Moroccan Atlas running south-west–north-east ; the high Atlas, flanked on the north by the mid-Atlas and on the south by the anti-Atlas; the two latter being virgations of the high Atlas. The mid-Atlas lying between the Moroccan meseta and the meseta of Oran is, in general, only slightly folded; under the name of mid-Atlas are included very different regions, to the west of Ulmes, an Archaean peneplane dissected by erosion, to the east of Ulmes Jurassic limestone plateaux covered by recent Pliocene and Qua ternary eruptive rocks (country of the Beni Mtir and of the Beni-Mgild), and, lastly to the south and the east, the chain properly speaking, which dominates the valley of the Muluya (3,80o metres at Mussa-ou-Salah). The mid-Atlas, where snows are abundant, is the chief source of water supply of Morocco; from it flows the Sbu, Wad Beht Bu-Regrag, Umm er Rbita ; inhabited by large Berber confederations, it is also the strong hold of resistance. In the angle formed on the east by the mid Atlas and high Atlas lies the upper valley of the Muluya, a high plain i,soo to 1,700 metres in altitude, which merges on the east into the Moroccan Dahra, itself continued in the steppes of the province of Oran. The chief affluent of the Muluya is the Mellulu; it diminishes owing to evaporation in the steppe-land, in some seasons its discharge is abundant, in others the stream is nearly dry ; the average discharge at Gercif is reckoned as 6 cubic metres. The high Atlas is divided into two parts, separated by the Tizi-n-Telremet (Tizi is the Berber word for "pass"). In the west are both primary and tertiary folds; schists and por phyries predominate. To the south of Marrakesh rise the highest peaks in Morocco and in the whole of North Africa ; Tubkal (4,225 metres), Wenkrim (4,173 metres), Likumt (3,906 metres) ; this great chain forms a barrier separating two distinct zones and proving a serious obstacle to communications. To the east
of the Pass of Teluet or Pass of the Glaoua (2,600 metres) crossed by the road from the Dra, the Atlas seems to be composed mainly of Jurassic limestones ; the outlines are softer, though the altitude is still about 3,00o metres, rising to 3,745 metres in Jebel Alachi. To the east of the Tizi-n-Telremet (2,200 metres), crossed by the road from Fez to Tafilelt, the Atlas dies down and breaks up into several series of heights separated by plains, and it eventually joins the Sahara Atlas of Algeria. To the south of the high Atlas, a transverse chain, the Sirua (3,00o metres) joins the high Atlas to the anti-Atlas; it is a volcanic massif with crystalline substratum. The anti-Atlas (2,000 metres) has a distinct individuality only between the Sirua and the Atlantic, on the east it is scarcely a plateau, little higher than the sur rounding country. The valley of the Sus is framed by the high Atlas, the Sirua and the anti-Atlas. East of the Sirua the drainage is to the Drata, which receives the Wad Dades ; after the great elbow which it makes south of Tamgrut, it receives only inter mittent feeders. The Wad Ziz, which receives the Todgha, called Ferkla and Gheris in its lower course, ends in Tafilelt. These Saharan wadi coming down from the Atlas are marked out by ribbons of irrigation-culture and by oases.
The temperature is equable and quite cool for the latitude on the west coast; at Mogador the January mean is 6i.5° F and the August mean 72.3°. Towards the interior the climate rapidly becomes more continental, with increased winter cold and very great summer heat; at Fez the January mean is and that of August 80.6°. The rainy season is from October–November to April–May; it becomes shorter and less severe as one goes south towards the belt of the trade-winds. The mean annual rainfall is 829 mm. at Tangier, 494 at Rabat, 391 at Casablanca, 404 at Mazagan, 36o at Mogador; on the coast the dew is very abundant. Towards the interior the rainfall diminishes (Marra kesh, 279 mm.), but it is higher on the western slopes of the mountain massifs. The country of the Jebala, the western mid Atlas, receives the highest rainfall; the regions of Meknes and of Fez, the corridor of Taza, open to the wet westerly winds, also have abundant precipitation (Meknes 555 mm., Fez 537 mm., Taza 600 mm.). Eastern Morocco, on the contrary, cut off from the moist winds by the great chains, is less favoured (Melilla mm., Ujda 357 mm., Berguent 157, Beni-Unif 154, Bu-Denib 13o). Snow falls several times a year at altitudes of above i,000 metres and disappears from the high peaks only at mid-summer.