Lieut. Newbold on the Geology of Egypt. 217 
increases the inclination diminishes, proving, Mr. Newbold states, 
that the strata were elevated to their present position with no more 
force than was necessary to produce the fissures or valleys; and he 
adds, that in proportion as the horizontality.is recovered, the fre- 
quency, depth, and extent of the fissures decrease. 
Some of the valleys, as that of Kossier, are considered to have 
been widened by aqueous causes no longer in operation, and that 
of the Nile by the still continued erosion of the river ; while others, 
as the Bahr-bila Maieh, or waterless river*, and that which separates 
the petrified wood formation from the Red Mountain, to have been 
formed entirely by them. The surface of these valleys is covered, 
for the greater part, with the detritus of the neighbouring rocks and 
of distantly transported rolled pebbles, which often rest on ledges 
and hills much above the general drainage-level. In the valley of 
Kossier, near the Red Sea, the gravel consists principally of pebbles 
of plutonic and hypogene rocks derived from the interior ; but near 
the hills or to the westward of the parent rocks few of these pebbles 
are found, proving, the author says, the eastwardly, direction of the 
transporting currents. 
The natural drainage of the country is remarkably simple. The 
greater portion of the small quantity of rain which falls in Central 
and Upper Egypt is absorbed by the deserts and collected in natural 
basins like the Oases; the remainder is partly carried off by the 
great evaporation, and partly conducted to the Red Sea by transverse 
cracks on the eastern side of the anticlinal axis, or to the valley of 
the Nile by similar cracks on the western flank of that axis. The 
drainage of the Libyan desert is also effected through the valley of 
the Nile. The amount of water which escapes by these means is 
however so small, that the Nile throughout the last 1350 miles, or 
about one-half of its course, does not receive what may be termed a 
single tributary. 
II. Formations—The deposits of which Egypt consists, are ar- 
ranged by Mr. Newbold under the heads of, 1. hypogene rocks with 
argillaceous schist, 2. breccia di verde, 3. lower sandstone, 4. marine 
limestone, 5. upper sandstone, 6. post-pliocene deposits, 7. drift, 
8. volcanic rocks, 9. alluvial accumulations, 10. sand-drifts. 
1. Hypogene Rocks.—These constitute a small portion of Egypt. 
Between the Red Sea and the Nile, Mr. Newbold observed them only 
in the latitude of Kossier (26° 8') resting against granite in highly 
inclined or curved strata, and forming an east and west zone 30 miles 
in breadth. He is of opinion that the same beds may probably range 
south by east, hypogene rocks appearing at Gebel Zerbara (lat. 
24° 30'). In a northerly direction they have been traced to the cata- 
racts, resting on “granite.” 
Gneiss, with thin “veins” of marbie, usually constitutes the low- 
est strata, which are overlaid conformably by micaceous, talcose, 
hornblende, and argillaceous schists and quartzite. Dykes or masses 
* Mr. Newbold objects to the opinion entertained by some travellers that 
this valley was anciently the channel of the Nile, as it contains no rich, 
dark-coloured alluvium. 
