[63]Schweinfurth appears to have been the first to examine these beds.
[64]One would imagine that there must have been a considerable amount of ferruginous matter in the water at the time of deposition of the Fluvio-marine series, the prevailing colours of the deposits being red and yellow.
[65]Mayer-Eymar appears to believe the depression of the Fayûm is the result of the volcanic activity which produced these basalt flows. He says (op. cit. Nouvelles recherches, etc., p. 218.) “Or, de cette extension extraordinaire du phénomène volcanique dans l’ouest du grand désert, il est, en premier lieu, permis de conclure que c’est par suite de son action excavante qu’a eu lieu l’effondrement rempli de nos jours, en partie par le lac de Fayum.”
Personally, we cannot see the slightest evidence in support of this. Where the basalt occurs as a hard band it usually causes steep cliffs as at Widan el Faras, owing to its protecting the underlying beds from denudation. To the west, in Jebel el Qatrani, its thickness and hardness determine the character and steepness of the escarpment below.
[66]Pebble bands are occasionally met with in the coarser sandstones of the Fluvio-marine series, and it would seem that from them are derived the pebbles of quartz and flint which so invariably strew the desert-surface to the north to beyond the latitude of Cairo. Those flints on the surface are largely broken up and flaked by changes of temperature, but show comparatively little shaping by blown sand; the white quartz pebbles on the other hand, while seldom or never broken or flaked, are invariably more or less facetted, frequently into typical “dreikanter” or pyramid-pebbles; below the surface both varieties are perfectly water-rounded.
[67]Many of the fossils mentioned in this profile were only discovered after long search, and had to be inserted in the measured section afterwards. Their position therefore is only approximate, as individual beds could not always be correlated at the different points where fossils were collected.
[68]It is not intended to convey the impression that remains of all these vertebrates were found at the point where the actual line of section runs. As a matter of fact at that particular point only Palæomastodon remains were observed, while most of the others were obtained some distance further west. Remains of Mœritherium, probably identical with M. Lyonsi, of the Qasr el Sagha series, in the shape of a beautifully-preserved and almost complete skull, associated with Palæomastodon and Arsinoitherium in these same beds, I only discovered in January 1903, at a point nearly due north of the western end of the Birket el Qurûn. A preliminary description of this skull has been published by Andrews, Further Notes on the Mammals of the Eocene of Egypt; Geol. Mag. Dec. V. Vol. I. No III. March 1904, pp. 109-115.
[69]Andrews and Beadnell, A preliminary notice of a Land Tortoise from the Upper Eocene of the Fayûm, Egypt, P.W.M. report, Cairo, 1903.
[70]In addition to those described from the Survey and British Museum collections, some additional species are described by von Reinach from von Stromer’s collection: Schildkrötenreste aus dem ägyptischen Tertiär; Sonderabdruck aus den Abhandlungen der Sendeenbergischen naturforschenden Gesellschaft, Band XXIX, Heft I. Frankfurt 1903.
[71]Op. cit., p. 455-456. Vide Blanckenhorn, Zur Kentniss der Süsswasserablag. u. Mollusken Syriens. Palaeontographica XLIV, 1897, S. 97, t. 8, f. 2.