Page:Africa by Élisée Reclus, Volume 1.djvu/109

 millions of people dwell in the Nile basin, which might yield corn sufficient for a vastly larger population.

The brown or blackish mud of the Nile is the only manure required for the crops. In the sun it becomes solid and may be cut into bricks or vessels; under the foot it is hard as stone, and in shrinking develops deep fissures in the ground. The old sandy or calcareous deposits, mingled at the foot of the hills with the rolled shingle washed down by floods anterior to the present geological epoch, are covered with a layer from 35 to 40 feet thick, forming an extremely rich arable soil which, if removed elsewhere, might suffice to fertilise a region a hundred times more extensive.

In its chemical composition this Nile mud, from which Egypt has been created, differs from that of all European rivers. Its analysis yields the most varied results according to its age, locality, and distance from the river. But it always contains a considerable proportion of carbonates of lime and magnesia, of oxide of iron and carbon, derived from decomposed organic substances. Palatable as it is, the Nile water nevertheless contains the refuse of all the provinces in its vast basin — the slime of the Atbara, animal remains from the Bahr-el-Azraq lagoons, sedge and other vegetable débris from the Kir and Gazelle rivers. Between the sands, argillaceous clays, and rugged crags of both deserts there thus intervenes a narrow belt of verdure created by the miscellaneous sedimentary matter in the course of ages washed down from half the continent.