The Fayûm and Lake Mœris

by R. H. Brown

CHAPTER IV.

HISTORY OF THE FAYÛM PROVINCE — THE FAYÛM BEFORE LAKE MŒRIS.

The past history of the Fayûm Province was probably the following.

In the beginning, the sea covered the whole of the area which afterwards became the Nile Valley and its bordering hills. By a slow process of upheaval the dry land appeared above the level of the waters, but, in the process, what was formerly the uniform bed of the sea became an uneven surface with heights and depressions and faults.

The Nile Valley, the Fayûm and Wadi Raiân depressions were the ultimate result of this action, the formation of the Nile Valley being completed by the flow of water. At first the upper reaches of the Nile Valley held its waters at a high level by barriers of rock, but in process of time these barriers were cut through, the bed scoured out by the constant flow of water, and the water surface lowered beyond its present levels, to be again gradually raised to the levels of to-day. The lower reaches of the Nile Valley were probably at first occupied by the sea, until the yearly deposit of the floods formed the Delta, and pushed the land thus formed further and further out, forcing the sea to retire. As the surface of the Delta became raised and prolonged by successive annual deposits, the bed and water-surface of the Nile also would have risen with it, until the levels at which the Nile flowed in its lower reaches became those of the present day.

At a point in the hills dividing the Nile Valley and the Fayûm, about 10 kilometres south of Lahûn, near Sidment-el-Gebel, Dr. Schweinfurth found “the indubitable witnesses of a Pliocene sea” preserved in the form of oysters (Ostrea cucullata and Pecten) in the white sand at about R.L. 60 to 70. (See [map] and [Plate XXI.]) The Pliocene sea, he maintains, intruded up the Nile Valley and extended on both sides of it as far as the contours of 60 to 70 metres above sea-level allowed. The place, where the oysters in the white sand were found, is situated in a flat depression on the plateau of the narrowest part of the hills separating the Nile Valley and the Fayûm. The Pliocene sea flowed here from one depression into the other, and would have succeeded in scouring away the barrier between the two depressions, if it had not been interrupted by a later upheaval or a withdrawal of the sea. In a similar manner there seems to have been made from Lahûn to Hawârah, the present communication between the Nile Valley and the Fayûm by which the Bahr Yûsuf entered to form Lake Mœris, either as an old Nile-arm or as an artificial branch of the natural arm.

Besides this passage, the desert tract on the north of it offers, as breaks in the higher ridge, several depressions, which must have been accessible to the Pliocene sea. The present railway line to the Fayûm crosses the hills at one of these depressions.

On account of the regularity of the limestone strata in the Fayûm and Wadi Raiân, a violent upheaval cannot be supposed to have been the cause that produced these two depressions, and it is more likely that they are the results of erosion and scour.

In a passage I have already quoted from Mr. Petrie’s writings, he states that in prehistoric times the Nile was a vastly greater river than it is now, due to an enormous rainfall. Let us then assume the Pliocene sea-level at R.L. 60 to 70, according to Dr. Schweinfurth, and an enormous volume of water coming down from the Upper Nile Valley according to Mr. Petrie. The sea which then invaded the Nile Valley would have been in communication with the Red Sea, and may have had a tide of 5 metres range, which would have complicated the currents, and added to the scouring action. Below Wâstah, the channel of the Nile Valley, contained between the Libyan and Arabian Hills, is much contracted. Under these conditions the floods from the Upper Nile would escape sideways through the depressions in the Libyan Hills into the Fayûm and the Wadi Raiân; into the latter by way of the Wadi Muellah, and possibly by other connections with the Nile Valley of a low enough level.

A large volume of water would thus be forced westwards out of the Nile Valley, and would find its way towards the sea to the west of Alexandria. In its endeavours to dig out a channel for itself it would erode laterally, or scour down vertically according as the softer material was found in one direction or the other. The different points of delivery and volumes of the water contributing to the flow, and the nature of the rock met with in its path would determine the form the channel would take at the various stages of its development. Tremendous eddies would be produced by projections of hard rock and contractions of the irregular channels, which would lift material from the bed and produce deep holes.