Page:Africa by Élisée Reclus, Volume 4.djvu/87

PHYSICAL FEATURES OF SOTTTI^^^T.ST AFRirA. 08 considerable?. Eiist of WulviHch Hay this intervening' space eonstitutcn the Naniiub district, that is, the vlahtv or nld of the Dutch, and the plain of the English Bettlers. It niuy in some resixxits be compared to the hamaiiaH of Arabia and North Africa, for although it presents the general appearance of a plain, the traveller crossing the Namieb in the direction from west to east is continually but imperceptibly ascending, until at GO miles from the Huy he finds himself 2,0()() feet above the level of the sea. Seen from the coast the veld masks the profile of the inland mountains, yet as he scales the crests of the dunes the wayfarer fancies he has before him a perfectly level plain with a boundless horizon. The German explorer StuplF thinks that the Namieb is an old marine Ix'd, its a8|)ect being that of an immense shallow basin of a shifting brown and whitish colour. During the dry season, that is, throughout the greater part of the year, the surface is as hard as that of a paved street ; but it becomes very difficult to traverse when the rains have softened the upper layer of calcareous or gypseous clay with which the sands are agglutinated in a concrete muss. At this season the cartwheels leave behind them deep ruts which may be traced years after- wards. The rainwater, which lodges in the few depressions scattered over the surface, slowly evaporates, leaving in its place tine gypseous or saline efflDrescences, the so-called salt-pans of the English settlers. In the vicinity of the hills the detritus is seen here and there of gneiss, quartz, or schistose rocks, which appear to have been decomposed by weathering, leaving on the ground patches of diverse colours. A few still standing blocks present a smooth surface, that has been polished by the action of the sands driving before the winds. The lower part of the gently inclined Namieb plain, which descends down to the coast, is covered with sandy dunes, and varies breadth from a few thousand yards to sixty miles inland. Some of these dunes rise to heights of considerably over 300 feet, and are conseqijently as elevated as those of the landes skirting the south-eastern shores of the Bay of Biscay. They are disposed in numerous parallel chains separated by intervening: depressions, which are themselves dotted over with hillocks of smaller size. South of Walviseh Bay no less than six of these siindy ridges have to be successively traversed to reach the interior. Their slopes facing the marine bteezes are nearly solid, while the opposite side, being strewn with arenaceous particles brought by the land wind, is of a much looser texture. A few herbaceous and scrubby plants with trailing roots grow on the surface of the dunes, and help to consolidate them by binding the sand together. These coast dunes have their origin probubly in ancient upheaved sandbanks, whereas those of the interior have been formed on the spot by the disintegration of the gneiss rocks under the action of solar heat. The process of upheaval would appear to be still going on along this section of the seaboard. To a height of (io or 70 feet above the present sea-level occur saline tracts strewn with shells which resemble those still surviving in the neighbouring waters. At an elevation of nearly 100 feet and at a distance of over half a mile inland there are even found entire skeletons of cetaceans formerly stranded on the old Ix^ach. On the raised