785 
stone of apparently limited extent, and confined to the southern part 
of Egypt, passing thence into Nubia, It is displayed on both flanks 
of the anticlinal axis between Kossier and Ghennah, reposing near 
Bir Anglaise conformably on greenstone; it is exposed also on the 
banks of the Nile, and, according to, Lefevre, it ranges from a little 
south-west of Esneh (lat. about 26° 10’) nearly to Syene or As- 
suan, 70 miles, where it, is dislocated by the syenite, and near its 
junction with that rock passes into aconglomerate and becomes aga- 
tiferous ; it also, from the smallness of the fragments composing the 
breccia strata, and the altered crystalline structure of the mass near 
the plutonic rocks, often resembles certain porphyries, but the true 
nature of the rock is easily recognizable in the beds at a greater di- 
stance. ; 
This sandstone varies from a loose siliceous aggregate with a fels- 
pathic, calcareous or ferruginous cement, to a compact quartz rock ; 
and the pebbles in the interstratified breccia consist usually of chert, 
flinty slate, agate or jasper. Associated with the sandstone are occa- 
sionally thin beds of green and purple clay, containing gypsum and 
chloride of soda. Veins of white, brown, and amethystine quartz | 
also traverse it, and copper as well as specular iron ore are stated to 
have been found in it near Hummamet. This sandstone was exten- 
sively used by the ancients. The vocal Memnon and many of the 
sphynges which line the dromos of the temple of Carnac consist of it. 
Mr. Newbold hesitates to decide the geological position of the 
formation, though Ehrenberg considers it to be the representative of 
the Quader sandstein, and Lefevre of the Keuper or Marnes Irisées*. 
4, Marine Limestone.—The sandstone is overlaid conformably by 
a marine limestone, which covers the greater part of Egypt, from near 
Esneh to below Cairo, or from lat. 25° 10! to lat. 30° 2’, and from 
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 band, 
* Bull, Soc, Géol, de France, tome x. 
