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. Thus, in consequence of the former action of rain on the surrounding hills, greater or less at different points along the borders according as the inclination of the adjacent watersheds was towards or away from the depression, and in consequence also of the deposition of Nile mud by the annual entry of the river flood, the bed of the lake formed in the depression would take the shape shown by the contours on the diagram of the Fayûm, Plate XIX. The former of these processes of change of the bed and borders of the depression may have ceased before the latter commenced to operate, or both may have acted simultaneously or alternately, which would account for layers of Nile mud being found near the Hawârah pyramid lying below the water-borne detritus of the hills. From a knowledge of the rules which govern the formation of a Delta, and the consequent raising of the level of the river which forms it, we might conclude that the Nile floods in past times were not as high as they are nowadays, though on the other hand we do not know that the floods were not greater in volume, and the probability is that they were. But whatever may be the truth about former Nile levels, the levels, at which Nile deposits are found in the Fayûm, furnish evidence of the maximum height to which the flood waters rose in the Lake.