Lieut. Newbold on the Geology of Egypt. 219 
the Red Sea to the Libyan desert, with the exception of the tracts 
occupied by plutonic and hypogene rocks near Syene, and in the 
centre of the Egyptian desert, constituting for the greater part the 
basis of both deserts. Mr. Newbold considers the limestone on the 
eastern shore of the upper part of the Red Sea, extending to the 
base of Sinai and far into the Arabian desert, to be also of the 
same age. The dip is considerable as well as variable in the vicinity 
of the plutonic rocks ; but there is scarcely any perceptible inclina- 
tion in the beds composing the banks of the Nile; the general bearing 
of the dip is, however, decidedly towards the north. 
The upper beds abound with Nummulites, and are generally hard 
and compact, but sometimes singularly honey-combed, apparently 
from the removal of the organic bodies. They are often siliceous, 
and considered, from effervescing slightly, to contain sometimes mag- 
nesia. The colour is buff or brown. 
The lower beds have a cretaceous aspect, and contain, near Thebes 
and Bir Anglaise, nodular as well as tabular layers of chert, which are 
occasionally replaced by Egyptian jasper and agate, likewise in- 
numerable small siliceous or cherty spheroids surrounded with a bard, 
and called by the Arabs Nuktah, or drops. These concretions are 
sometimes uniied in pairs, and often present various modifications of 
a spheroid. Ehrenberg has not been able to detect any traces of 
organic structure in them, but he has noticed fragments of granite 
and other rocks. The lower beds yield also layers of earthy and cry- 
stallized gypsum, chloride of soda, arragonite, large deposits of stalag- 
mite or Egyptian alabaster, near Tel el Amara (lat. 27° 43') and in 
the Mokattem range, 8 hours from Benisuof; also in caverns fine 
stalactites, used in the arts. Among other mineral products, Mr, 
Newbold mentions sulphate of barytes, lead, crystallized sulphur, and 
nodules of carbonized vegetable matter. Interstratified with these 
lower beds are greenish and pale brown marls, the softer portions of 
which are usedin washing, and the harder as whetstones. This lime- 
stone was employed in constructing the earliest Egyptian monuments, 
According to Ehrenberg, the lower beds of this formation contain 
Infusoria and Foraminifere found in the Chalk of Europe ; and to 
Lefevre*, Echinites at Esneh similar to those of Malta, also speci- 
mens of Hippurites, Placuna, and Vulsella, and a fish near Cairo; 
large Nautili, and numerous other testacea, with remains of crabs, 
fishes’ teeth and corallines, were collected by Mr. Newbold. The 
author refers also to Mr. Bowerbank’s observations that the Egyptian 
jaspers present no spongeous structure, but contain numerous Fora- 
miniferz resembling those found in chalk flints, yet difficult to distin- 
guish from species obtained in the calcaire grossiert. 
5. Upper Sandstone.—This formation occurs in horizontally strati- 
fied hummocks and patches resting on the marine limestone ; and it 
has been traced from the Mediterranean far into the Nubian, Li- 
byan and Baytida deserts, and even into Abyssiniat. The hummocks 
* Bulletin Soc. Géol, de France, tome x. pp. 144, 234. 
t See Phil. Mag. 8. 3. vol, xix. p. 546. 
t Lefevre, Bull. Soc. Géol. de France, tome x. 
