Along the north side of the Fayûm depression, to the west of Elwat Hialla, the gravel terraces are almost absent, having been removed nearly completely by denudation. That the terraces once existed throughout this region is however shown by the small patches met with to the north-east of Widan el Faras, the eastern extremity of Jebel el Qatrani, and at several points high up on the escarpments as far west as the western end of the lake. Beyond the latter point these terrace gravels have not been noticed; the slopes of the depression become more and more obscured by loose superficial flints washed down from the plateau, and the existence of underlying terrace gravels could only be shown by detailed mapping. [Illustration: 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. [Illustration: PLATE XIV. PLEISTOCENE LACUSTRINE CLAYS WITH TAMARISK STUMPS IN SITU AT 50 METRES ABOVE PRESENT SURFACE OF THE BIRKET EL QURUN.]