Page:Africa by Élisée Reclus, Volume 1.djvu/172

 On the whole, the Ethiopian plateau consists of numerous distinct table-lands, like the polyhedric prisms formed by the dessication of the clayey soil of plains exposed to the action of heat. These table-lands, intersected by precipices and surmounted by crags, stand at different elevations. Some of them form entire provinces, with towns and numerous populations; others, the so-called amba, are mere blocks or quadrangular masses some 800 or 1,000 feet high, similar to the drugs or "inaccessibles" of Southern India, or the isolated crags of Saxon Switzerland. In eastern Ethiopia the origin of these ambas is doubtless due to the disintegration of a thick layer of red or greyish sandstone, cleft into vertical masses, and revealing here and there stratas of lower schistose and crystaline formations. In the interior, and especially towards the west, where volcanic lands prevail, most of the natural cliffs consist, not of sandstone, like those of the eastern plateaux of India and of Saxony, but of lava, and terminate in basaltic columns, some disposed in converging clusters or else forming colonnades like the temples of the Acropolis. These crystaline rocks, whose upper terrace is large enough to contain arable tracts and form the source of rivers, have for the most part served as strongholds, where many a tribe or horde of robbers has remained for years besieged and cut off from the rest of the world. Other ambas have been chosen by the monks as the sites of their monasteries, and such holy places often serve as sanctuaries to those fleeing from justice or oppression. Lastly, the smaller basalt columns are frequently used as prisons for the great personages who have incurred the displeasure of the reigning sovereign.

In Eastern Ethiopia the general face of the plateau is more broken and cut up into more secondary plateaux and crystaline rocks than in the west. The escarpments of most of the isolated mountain masses slope more gradually westwards. They thus reproduce in miniature the general aspect of the whole region, which terminates abruptly towards the Red Sea, and slopes gradually towards the Nilotic plains. This general incline, however, can only be determined by accurate instruments, the aspect of the plateau and of the surrounding ranges being too irregular to enable the observer to detect its primitive outline. The ambas stand out at various elevations in bold relief against the blue sky like citadels and towers. Lower down, the verdant base of the plateau breaks into abrupt precipices, whose walls present from a distance the aspect of regular quadrangular lines. On these harder rocks rest the soft foundations, here scored by avalanches of falling rocks, elsewhere clothed with verdure. The Abyssinian landscapes, like those of the Rocky Mountains, consist of superimposed terrace-lands and vast strata of monumental aspect. Near Magdala the eastern edge of the Talanta plateau is said to terminate abruptly in a vertical wall of basaltic pillars over three thousand feet high.

The height of the Ethiopian plateaux varies greatly, presenting between the Sim^n range in the north and those of Lasta and Gojam in the south-east and