388 Dr. W. F. Hume— Origin of the Vile Valley. 
the Araba anticline, while no Miocene strata have been found in the 
Araba depression itself? The evidence, as I read it, points to this 
region having been a domed area during Miocene times, and I can 
conceive of no erosive agent which would break across this great 
earth-feature without the intervention of fracture. Beit remembered, 
too, that the regularity of the parallel ranges (Gebels Esh, Zeit, etc.) 
further south is geologically more apparent than real. In the Esh 
range, as I pointed out in the Eastern Desert Memoir of 1897, on 
the westward flank of the hills, the strata follow one another in 
proper succession, dipping westward as the one-half of a regular 
anticline. To the east of its central cone of igneous rocks what 
appears? Except towards the northern end of the range none of 
these well-developed strata (from Nubian Sandstone to and including 
the Lower Eocene) are anywhere present, in their place being a high- 
tilted Miocene coral-reef. Surely such an inequality as this cannot 
be lightly passed over, and until good proofs to the contrary are 
submitted to me I consider that faulting and faulting alone can 
explain the phenomena. 
In Sinai the intensity of the faulting is so obvious that I await 
wider confirmation of its extent with equanimity, believing that the 
excellent effort made by Mr. Barron to unravel this most difficult 
problem will remain a permanent monument to his zeal and his 
industry. Very few would have done as much, or even a tithe as 
much, in the time at his disposal, and under the physical conditions 
which he was called upon to face. Only those who know something 
of the bitter cold of a Sinai winter, or the blinding sandstorms of the 
country between Suez and Tor, can appreciate his labours at their true 
value, and will be able to treat in a lenient spirit any errors of detail 
that may be revealed by subsequent close research in connexion with 
developing industries. As regards the eastern portion of Sinai, I have 
not one word to withdraw from the account of the rifts given in my 
memoir on that region, considering that the trough-fault view is the 
only explanation which satisfies all the conditions, geological and 
physical, presented by the parallel valleys of that complicated 
mountainous region. 
The conception which seems best to satisfy all the conditions of 
Egyptian geology appears to involve a major north and north- 
westward folding which in the oases, though marked, and in the 
first instance originating those depressions, has nevertheless only 
produced fracture effects to a minor extent. (This statement is 
necessarily relative, for those who have read Mr. Beadnell’s ‘“‘ An 
Egyptian Oasis’? will remember the important fracture-line determining 
the line of wells in Kharga Oasis.) 
In the Nile Valley erosion seems to have been the principal factor, 
the river either following the outcrops of the softer strata or the 
synclinal portions of the fold. The many fault-systems bordering it, 
especially on the east (Cairo—-Suez region, Helwan area, Qena—Luxor 
slip-fault district, Kom Ombo plain), are not in direct relationship to 
the present course of the river, or in the case of the great slip-faults 
only appear to be so, the limestones in the cliffs bordering the Nile 
slipping on and crushing the Cretaceous shales underlying them. 
