no 
MR. HORNER ON THE ALLUVIAL LAND OF EGYPT. 
west direction until it gradually sinks in the desert of Libya. This part of the range 
nowhere rises to a greater height than about 214 feet above the bed of the Nile, and 
546 feet above the Mediterranean. Granite is the predominant rock, of different varie- 
ties, sometimes passing into gneiss, sometimes having an admixture of hornblende, 
when it gets the name of syenite, from its occurrence near the ancient town of Syene. 
The granites and other unstratified rocks are associated in the district near As- 
souan, or the First Cataract, with two sedimentary rocks, both sandstones, and very 
similar in mineral structure, but very different in point of age; for the one belongs 
to the lower members of the cretaceous period, and the other covers in several places, 
farther north, a tertiary nummulite limestone. 
Through a labyrinth of these granites and sandstones, extending from the island 
of Philse to the neighbourhood of Assouan, the Nile enters Egypt in a succession of 
rapids, having a descent of about 85 feet in a distance of about five miles and a half 
from Philse to Assouan, forming what is called the First Cataract. There is no water- 
fall, as commonly understood by the term cataract, for Russegger and his com- 
panions were dragged up in a boat the whole distance in two hours, during the time 
of low water, that is, towards the end of January. 
The valley of Upper Egypt is flanked by two parallel ranges of hills, the Arabian 
on the east, the Libyan on the west. At Assouan, the southern extremity of the valley, 
they each approach close to the Nile, the bed of which is strewed with rocky islands, 
the most northernly being the celebrated Elephantine. Both ranges are divided by 
rents of various magnitudes, forming valleys, some of them running north and south, 
others crossing the ranges from east to west. One of the great north and south valleys 
gave a passage to the waters of the Nile, in a somewhat tortuous course ; the appear- 
ance of the boundaries on either side, and the very gentle fall of the land, from south 
to north, excluding all idea that the valley has been excavated by the action of run- 
ning water. The Nile valley varies considerably in breadth, its widest part between 
Minieh"^ and Benisuef being about eighteen miles, frequently contracting to two 
miles; and at Gebel Silsilis, about forty-five miles below Assouan, the hills approach 
so close to each other, that the river, for three-quarters of a mile, runs through a pass 
about 1200 feet wide-f-, and there is scarcely a yard of alluvial deposit on either bank 
for a considerable distance. At the apex of the Delta the valley is six and a half 
miles wide:};. 
The Libyan range falls with a slope towards the valley, the rocks of which it is 
composed appearing to extend under the valley, forming a solid basin covered with 
sand and detritus that had accumulated before the alluvial matter brought down by 
the Nile began to be deposited over it. 
The Arabian hills, except where broken by transverse valleys, present cliffs towards 
* In the spelling of the proper names, I follow Lepsius in his Briefe aus ^gypten, 1852. 
i" According to the atlas that accompanies the Description de I’Egypte, 200 Toises. 
I Bonomi, Trans, of Ro}^ Soc. ot Lit., 2nd Series, ii. 297. 
