Had this action not been arrested by the further upheaval of the land, perhaps a second Nile Valley would have been formed branching from the main valley at Behnesa, passing through the Wadi Raiân and Fayûm depression, and continuing through the Wadis Fadhi and Faragh, west of Memphis and Cairo, to the Natron Lakes, and thence to the sea west of Alexandria; or returning to the Nile Valley, or side of what is now the Delta, but was then sea, at some point south of Alexandria.
If this theory is a sound one, the remarkable depressions of the Fayûm and Wadi Raiân are paralleled on a small scale by the deep holes (bayarât) scoured out below the bridges or cuts in the Upper Egypt Basin embankments, or outside a breach in a Nile bank.
The section, given on [Plate XVIII.,] of 50 miles of the Nile Valley and desert opposite Cairo, is taken from Mr. Cope Whitehouse’s article, entitled “The Pyramid Hill of Gizeh,” which appeared in the ‘Quarterly’ some time ago. It shows (assuming it on Mr. Whitehouse’s authority to be a correct representation of the ground) the channels, that I have named, in the arrested state of development which they had reached, when the flow of water, which was digging them out, was cut off.
Plate XVIII.
SECTION OF 50 MILES ON LAT. 30°.
Borrowed from Cope Whitehouse.
Note.—The dotted line represents the level of the Pliocene Sea, but is not in Cope Whitehouse’s section, which was drawn for another purpose.
After the upheaval had raised their borders above sea-level, the sea would be henceforward excluded from the depressions and be replaced by the waters of the Nile, which would have entered by the gap in the Libyan Hills at Lahûn. The upheaval continuing and the Nile at the same time scouring out its bed, a condition of levels would have come about, under which there would have been an annual inflow during the floods and outflow into the Nile on the floods subsiding.
In a long series of years there would result a thick deposit of Nile mud in the Fayûm, the richest deposit being found near the point where the waters first spread themselves out after passing through the comparatively narrow defile in the Libyan Hills. The tendency of the entrance of the waters, heavily charged with silt, into an extended basin filled with water would be to form a delta of Nile deposit similar to that which the Nile itself has formed in entering the sea, modified by the form of the basin bed, which would not have been uniform like that of the sea. On account of the momentum of the body of water leaving the defile and entering the lake, there would be formed a projecting ridge (contour R.L. 23) of deposit in the direction of the flow, while the deposit, resulting from the end and side spills, would form in gentle slopes with approximately parallel and rounded contours (R.L. 17 to 10) on both sides, and at the end of the projecting ridge as shown in [Plate XIX.]