GEOLOGICAL HISTORY OF EGYPT AND THE NILE VALLEY. 319 
and disturbance, and for faulting and flexuring of strata. 
Large areas of what had been for ages the bed of the 
ocean were converted into dry land, and along with this 
elevation of the strata extensive denudation was carried on 
by wave and river action. We may go so far as to say that 
to the Miocene period is to be referred the development of 
the leading physical features of the region here treated of, 
together with both Syria and Palestine. Owing to this 
cause, Miocene strata are of rare occurrence, as the period 
was one of denudation rather than of deposition of strata. 
Nevertheless, strata both of marine and lacustrine origin, 
referable to this period according to Zittel, are to be found 
in isolated positions not much elevated above the sea level, 
as for example in the Oasis of Siuah, or Ammon, and adj olning 
plateau of Barco, at Jebel Geneffe north of Suez, and a few 
places bordering the Gulf of Suez, to the south of that place. 
The strata, consisting of limestone, marls, and sand in these 
localities, are generally of marine origin, as indicated by the 
fossils, which include Peeten, Spondulus, Ostrea of several 
species, Placuna, and Sea-urchins, such as Echinolampas, 
Scutella, Clypeaster.* They appear to be conformably super- 
imposed on the Upper Eocene beds at Siuah; but in the case 
of the beds near Suez, they occupy positions in reference to the 
Nummulite limestone, which show that that formation had 
been upheaved and largely denuded previous to the deposi- 
tion of the Miocene strata. They may therefore be regarded 
as representatives of the period locally deposited where the 
sea-water prevailed in the vicinity of the emergent lands. 
5. Pliocene or Pleistocene Strata—The representatives of 
this period consist of raised beaches and shore beds with sea 
shells and corals found at intervals on both sides of the plain 
of Lower Egypt, and at an elevation of 200 to 220 feet above 
the present sea level (Fig. 2). In the oases of the Fayfiim and 
Rayan basins, by beds of sand, loam, and marl, with sea shells 
such as Jurritella transitoria, Mayer, T. turris, Bast, T. carini- 
fera, Corbula py«idicula, Tellina pellucida, Desh.,t &e., and in 
the Nile Valley by terraces of gravel, sand, and loam, rising 
for 100 to 130 feet above the highest inundations of the river 
in the neighbourhood of Assouan. When these beaches and 
terraces were in couse of formation, the gulf of Lower 
* ‘Lhe Pliocene beds of Siuah were first noticed by Ehrenberg in 1820, 
those of Suez by O. Fraas, Fuchs and Schweinfurth. Plates of fossils are 
given in Zittel’s work, Plates I, IJ, ITI, and IV, &c. 
+ Figured in Plate XXIII of Zittel’s Libyschen Wiiste, 
