GEOLOGICAL HISTORY OF EGYPT AND THE NILE VALLEY. 315 
Mt. Agrib, in the Arabian Mountains. They also constitute 
the mountain masses of the Sinaitic Peninsula, and the 
flanks of the Edomite range on the borders of the table-land 
of the Arabian Desert.* They consist of micaceous, horn- 
blendic, and chloritic schists, clay-slate, and quartzite, with 
numerous granitic veins, below which are beds of gneiss and 
schist with dykes of granite and diorite, which have been 
used in Egyptian works of art. According to Dawson, this 
older series, which may be referred to the Archean age, is 
overlain unconformably by a second series seen at the Island 
of Biggeh, above the First Cataract, and near to Phile; 
which series consists of porphyry, gneiss, and porphyritic 
granite, all probably of Plutonic origin, and possibly referable 
to the Huronian Series of North America. Newbold has 
described granitic and schistose rocks as ranging from near 
the shore of the Red Sea at Kogseir inland, in a band about 
30 miles in breadth, forming a part of the great central axis 
of Mt. Agrib. The fundamental part of this range appears 
to be granite (or gneiss), supporting various schists, and 
penetrated by dykes of basalt, greenstone, porphyry, and 
serpentine. In Gebel Zubara are found emeralds, avanturine, 
and specular iron ore; and from the potstone, nephrite, and 
“green felspar” of Mount Baran have been sculptured 
cooking vessels, images, and scarabeel. 
In the same region is also found the celebrated Breccia di 
verde, resting on the slate in unconformable thick-bedded 
strata, containing angular fragments and rounded pebbles of 
greenstone, gneiss, slate, serpentine, and marble cemented by 
a slightly calcareous paste. This breccia has been largely 
used for ornamental work, in Egypt, Italy, and Constanti- 
nople.t ‘These old crystalline rocks form the core of the 
Abyssinian Highlands, and range into the region of the 
Central African Lakes by Mounts Kenia and Kilimanjaro. 
(2.) The Nubian Sandstone—This formation is found 
resting on the Archean crystalline rocks north of Assouan 
on both banks of the Nile, and on the flanks of the great 
central azis of crystalline rocks in the Arabian mountains. 
Having been extensively used by the ancient Egyptians in 
their works of monumental art, amongst which may be 
(with map); J. Russegger, “ Reisen in Europa, &c.,” Journ. Leonhard 
und Bronn ; Sir J. W. Dawson, Modern Science in Bible Lands, p. 556, &e. 
* “Phys. Geol. Arabia Petra and Palestine,” Mem. Palest. Explor. 
Society, 188%. 
+ Newboid, supra cit., p. 329. 
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