NEWBOLD ON THE GEOLOGY OF EGYPT. 331 
sandstone here, near its junction with these rocks, passes into pud- 
ding-stone and an agatiferous breccia. Near Bir Anglaise, in the 
Kossier desert, it reposes on the greenstone in conformable strata, 
dipping easterly: and west from this, on the opposite side of the 
anticlinal axis, it rests immediately on the Breccia di verde with a 
slight westerly dip. The sandstone breccias, near the junction-line 
with the plutonic rocks,—from the smallness of the fragments com- 
posing them, and their altered crystalline structure,—often resemble 
certain porphyries in lithological character, but at a greater distance 
in the higher beds their true nature is easily recognizable. 
Lithological Character.—In lithological character the sandstone 
varies from a loose granular aggregate of quartz, held together by a 
felspathic, calcareous, or ferruginous cement, to a compact quartz 
rock. The pebbles in its interstratified breccias are usually of chert, 
flinty slate, agate or jasper, many of them evidently derived from the 
subjacent clay-slate. In some situations it contains thin beds of 
green and purple clay, in which occur gypsum and crystallized 
muriate of soda. Veins of crystallized quartz—white, brown, and 
amethystine—traverse it. Copper and specular iron ore are said by 
Mr. Burton to oceur near Hummamet, which lies on the sandstone. 
Economical Uses.—This stone entered largely into the construc- 
tion of the temples of Upper Egypt and its colossi, for which purpose 
it was usually quarried at Hadyjar Silsilis, a little to the north of 
Syene, in immense blocks. The colossal statue of the vocal Memnon 
was hewn from this rock, and many of the sphinxes that line the 
dromos of the temple of Carnac. 
Age.—Ehrenberg* thought this sandstone formation identical 
with the Quader-sandstein of German geologists, and Russegger + 
with the Keuper, and the marnes irisées of French geologists ; but 
until farther information be obtained regarding its organic remains, 
and those of the marine limestone above it, we must hesitate to class 
it with any known European formation, though in mineral character, 
and its saliferous and gypsiferous nature, it certainly resembles our 
new red sandstone. 
Marine Limestone: Geographical Extent.—In conformable stra- 
tification, overlying the sandstone, extensive beds of marine lime- 
stone (d, fig. 1; 3, fig. 2) cover the greater part of Egypt, from the 
vicinity of Esneh on the south (lat. 25° 10’ N.) to below Cairo (lat. 
30° 2’ N.) on the north ; and, with some interruption from the in- 
trusion of plutonic and hypogene rocks which rise from beneath them 
near Syene, and the centre of the Egyptian desert, stretch from. the 
west shore of the Red Sea, across the valley of the Nile into the Li- 
byan wastes, thus constituting, for the greater part, the basis of both 
deserts. From an examination of the cliffs on the eastern shore of 
the upper part of the Red Sea, and the similarity of the fossil and 
mineral character of the two rocks, I am inclined to think that the 
strata were once continuous over this gulf, extending to the base of 
the plutonic axis of Sinai, and far into the Arabian desert. 
* Lond., Ed. and Dub. Phil. Mag. vol. xviii. p. 394. 
+ Bulletin de la Société Géologique, vol. x. pp. 144, 
