| PLIOCENE (to Pleistocene) | —1. | Terrace of gravel and conglomerate. |
| UPPER EOCENE-OLIGOCENE | —2. | Sands and sandstones. |
| MIDDLE EOCENE | —3. | Clays, marls and limestones of the Upper Mokattam. |
Fig. 9.—Sketch-Section through summit of Fayûm Escarpment at Elwat Hialla.
Near Widan el Faras the terrace occurs at a level of about 220 metres above the Birket el Qurûn, or 175 metres above sea-level, and consists of a 10-metre thickness of a semi-consolidated mass of boulders and pebbles of sandstone, limestone, and basalt, with fine gravel and sand, unconformably laid on to the variegated sandstones of the Fluvio-marine series.
In the neighbourhood of the Survey’s main excavations for fossil bones, to the north of Garat el Esh, several local remnants of the formerly more or less continuous gravel terrace were detected[87]. The height was probably more accurately determined here than elsewhere and the upper limit of the deposits was found to lie at approximately 170 metres above sea-level; this figure may indeed be taken as the average height of the Pliocene terraces throughout the Fayûm.
Plate XIV.
PLEISTOCENE LACUSTRINE CLAYS WITH TAMARISK STUMPS IN SITU AT 50 METRES ABOVE PRESENT SURFACE OF THE BIRKET EL QURUN.
Briefly then we have shown the existence of the well marked remains of a gravel terrace 170-180 metres above sea-level, throughout the south-east, east, and north sides of the Fayûm depression, and the first question that suggests itself with regard to these deposits is, whether they are of marine or of freshwater origin? From their position in part capping and in part perched on the flanks of the escarpments, it is evident that the depression of the Fayûm must have been partly formed before their deposition; probably it had approximately obtained to its present form and dimensions, except as to depth. The terrace certainly marks the shoreline of the sheet of water in which its constituents were deposited, and the surface of this water must have attained a height of nearly 200 metres above present sea-level. It is not unlikely that some of the extensive plains of the Fayûm may owe their existence in part to the presence in Pliocene times of the sea or of a large inland lake, that they may in fact be plains of denudation. The plain above the escarpment of the Qasr el Sagha series, lying between 150 and 200 metres above sea-level, and stretching throughout a large part of the north of the Fayûm, has characters which tend to support this idea.
Unfortunately the gravels are entirely barren of contemporaneous organic remains, with one exception; near Ez. Qalamsha some examples of Ostrea cucullata were discovered, and these we believe to have truly belonged to the lower beds of the terraces and not to have been derived from the undoubted marine Middle Pliocene beds of Sidmant. If the existence of O. cucullata in these terraces could be confirmed we should undoubtedly class them as marine and of Middle Pliocene age. But the single evidence of the Qalamsha shells is not sufficient, and confirmatory occurrences must be obtained and, if possible, the relation of the terraces to Schweinfurth’s marine Sidmant beds determined, which has not been yet done.