216 Lieut. Newbold on the Geology of Egypt. 
sand-covered rocks, intersected by deep ravines. The peculiarly ta- 
bular features of Central and part of Upper Egypt are due to the ho- 
rizontal stratification of the prevailing limestone, which supports the 
desert districts, and terminates near the*banks of the Nile, from Esneh 
to Cairo, in mural escarpments. Between Kossier and Ghennah the 
aspect is rendered more varied and irregular by pinnacles and dome- 
shaped masses of plutonic or hypogene rocks. The deserts present 
a series of undulating plains sometimes studded with clusters of low 
hills, and are covered chiefly with unproductive saline, often calca- 
reous and gypseous sand, marl, and gravel. The Oases of the deserts 
and the mountainous region, Mr. Newbold regards simply as valleys, 
supplied with moisture either by springs or by the drainage-water of 
the deserts, held up by. the impervious clay constituting the subsoil. 
In a few cases the moisture, he thinks, may be due to percolation 
from the Nile. The greatest altitude of the desert between Suez and 
Cairo is about 700 feet above the ‘‘ ocean;” and its general charac. - 
ter between the Red Sea and the Nile is that of a flattish irregular 
plateau rising towards the centre and terminating in each direction 
in abrupt escarpments. The flat marshy districts between Suez and 
Pelusium are stated, on the authority of Laborde, to be twenty-four 
feet below the sea-level. 
The aspect of the valley and delta of the Nile varies with the sea- 
sons, presenting while the country is inundated a vast freshwater lake, 
studded with palm-shaded hamlets ; and after the subsidence of the 
waters, exhibiting along the course of the river a line of brilliant ver- 
dure winding through higher sterile tracts. When the grain has been 
gathered, the prospect consists of one monotonous brown, dusty plain, 
traversed by the sluggish Nile. The dip of the country from the first 
cataract to the Mediterranean is, according to Mr. Wallace, only two 
inches in a mile; but the descent a little north of Assuan is seven 
inches, lessening however on approaching the delta, and the canal 
between the Nile and Alexandria, a distance of sixty miles, has not a 
single lock. 
From the horizontal stratification of the rocks composing the greater 
part of Egypt, it is difficult, Mr. Newbold says, to trace any particu- 
lar lines of elevation. The mural cliffs which flank the valley of the 
Nile to the vicinity of Cairo, there deviate towards the east and west, 
and similar but less abrupt cliffs flank both shores of the Red Sea. 
This horizontal formation is traversed by valleys and ravines or wa- 
dis, having a north and south, and east and west direction, or which 
intersect each other at right angles, the most considerable being that 
of the Nile. 
In the eastern desert of Upper Egypt, Mr. Newbold traced these 
valleys to a north and south anticlinal line, caused by plutonic rocks 
which attain an altitude of 1000 feet above the sea-level ; and their 
upheaval, he says, accounts for the intersecting systems of valleys, 
and illustrates forcibly the truth of Mr. Hopkins’s observations on the 
laws of fracture. In the vicinity of the erupted rocks the sedimentary 
strata exhibit considerable proofs of disturbance, but as the distance 
