Page:Africa by Élisée Reclus, Volume 2.djvu/438

 »G0 NORTH-WEST AFEIOA. the parallel " snake " ridges, the Draa, exhausted by the irrigation canals branch- ing right and left through the plantations, is no longer able to maintain a regular course. It spreads out in the vast Dcbaya depression, which is alternately a lake, a swamp, and a watery plain, on which crops of cereals are raised. Below this depression it trends towards the south-west, h(?re flowing between high banks, and receiving a number of intermittent torrents from the An ti- Atlas. But when these tributaries run dry, no surface water is left in its lower course, although, according to local tradition and historic records, it formerly reached the sea through a broad and permanent estuary. At that time crocodiles and hippo- potami frequented its waters, and elephants roamed in herds over the riverain forests. The stream, which under the names of Wed Zis and Wed Guers, flows due south from the northern extremity of the Great Atlas, after watering the Tafilclt oases, 150 miles from its source, runs dry in the sands of the desert. No traveller has yet ascertained whether its bed is continued southwards across the great dunes trending west towards the Draa, or east to the Messawara basin, or continuing an independent course in the direction of the Niger. The Wed Guir hydrographic system, which begins in the last cirques of the Great Atlas immediately cast of the Wed Zis, is better known in its upper course, thanks to the numerous expeditions made in this direction by the French forces, and to the reports of pilgrims and traders. After receiving the streams flowing from Figuig and from the Ish district on the Oran frontier, the Guir flows under various names in the direction of the Twat oasis. But beyond this point it is unknown whether it joins the Draa, loses itself in a land-locked basin, or effects a junction with the Niger towards the western extremity of its great bend towards the north. Climaie of Marocco. Marocco is entirely comprised within the zone of the trade winds ; but the normal play of the atmospheric currents is modified by the Atlas highlands, by the position of the country at the entrance of the Mediterranean, and the neighbour- hood of the Sahara. In summer the land and sea breezes alternate daily alono- the coast, while the prevailing winds come from the south. In winter, that is, from October to February, north-west winds are very frequent, bearin'>- with them a considerable amount of moisture, which is precipitated in abundant showers on the slopes of the Atlas. But throughout the southern regions the trade winds are predominant. As these blow parallel with the axis of the main ranges, the aerial current follows, so to say, a channel already created by the Atlantic slope of Mauritania. For about two hundred and seventy days in the year the polar winds from the north and north-east prevail at Mogador ; while for nearly two months, usually in winter, the opposite currents from the west and south-west descend from the higher to the lower atmospheric regions. Under the influence of the trade winds and marine breezes, the climate'of the