CHAP. I. ALLUVIAL DEPOSIT OF THE NILE. 9
of the constant advance of the land into the re- ceding sea.
To any person who has examined the levels of the alluvial deposit of the Nile in various parts of its course, as from the first cataract to its mouth at Rosetta*, it is well known that the perpendicular stratum of soil, if I may so call it, decreases in thickness as it approaches the sea ; and thus at Elephantine the land has been raised about nine feet in I7OO years, at Thebes about seven, and so on, gradually diminishing to the mouth. There, indeed, the deposit is lessened in a very remarkable degree, much more than in the same decreasing ratio, in consequence of the greater extent of the land, east and west, over which the inundation spreads ; so that, in a section representing the ac- cumulated soil and the level of the low Nile, the angle of inclination would be much smaller from the fork of the Delta to the sea, than from the Thebaid to the Delta. And this is satisfactorily proved by the increase of the banks and the surface of the country at Elephantine, Thebes, Heliopolis, the vicinity of old Cairo, and other places, where the positions of ancient monuments attest the former levels of the land's surface, and enable us to ascertain the in- crease within a known period. Around the base of the obelisk at Heliopolis, erected by Osirtasen I. about 1700 years before our era, the alluvial soil has accumulated to the height of five feet ten
- The banks during the low Nile are upwards of 30 feet high in
parts of Nubia, in middle Egypt 20, and decrease as they are nearer the mouth.
