Numerous small faults effects local.We have already stated that small local faults occur in various parts of the Fayûm and some of these may be specially mentioned. The most important is about 10 kilometres N.N.E. of Qasr el Sagha; the line of fault lies nearly north-west and south-east, has a length of six or seven kilometres, and affects both middle and upper Eocene beds; at its northern end the fault passes into a fold before finally dying out. Some of the Upper Eocene sandstones are hardened and silicified and form a succession of black knobs along the line of disturbance. To the south of these the axis of dislocation bends slightly eastwards and takes the form of a sharp fold; further south it again becomes a true fault, flanked by a line of highly tilted beds along its south-west side. The effects of this fault are very marked locally but entirely restricted to a limited area. The most important is the breaking of the continuity of the escarpment of the Qasr el Sagha series; the line of cliffs formed by those beds is a very marked topographical feature and the fault in question causes a lateral displacement of seven kilometres.
Fig. 1.—Fault near Qasr el Sagha.
In the neighbourhood of Qasr el Sagha and westwards for a considerable distance, small strike-faults are of common occurrence in the beds of the Qasr el Sagha series. As a rule these faults do not extend more than a few hundred metres in length, while the down-throw seldom exceeds two or three metres and in almost every case observed is to the north. The hade may be 65° or more. Fig. 1 shows an example near Qasr el Sagha. The most marked of these strike faults is seen to the east of Garat el Esh; commencing a little to the north-east of that hill it runs in a nearly due easterly direction till it cuts the cliffs of the Qasr el Sagha series after some five kilometres. Its down-throw is to the north and never exceeds a few metres; this small throw is however sufficient to cause a marked displacement of the highest bed of limestone forming the dip-slope surface of the plateau at the summit of the Middle Eocene beds.
At first sight it might be suspected that the very irregular trend of the different escarpments throughout the Fayûm was determined or influenced by fault lines; an extended examination of the cliffs however gave negative results, with one exception; the long narrow hill-mass to the north east of Gar el Gahannem is bounded by faults on both sides and that on the west can be easily traced for seven or eight kilometres northwards, and throughout its length its influence on the topography is very conspicuous.
[26]Beadnell. The Fayûm depression: A Preliminary Notice of the Geology of a District in Egypt containing a new Palaeogene Vertebrate Fauna. Geol. Mag. Dec. IV, Vol. VIII, No. 450, Dec. 1901, p. 540.
[27]See reports on Kharga Oasis (1900), Farafra Oasis (1901), Dakhla Oasis (1901), and Baharia Oasis (1903), issued by Survey Dept. P.W.M., Cairo.
[28]Public Works Ministry Report. Cairo, 1899.
[29]Blanckenhorn. Geologie Aegyptens, Berlin 1901, Pt. IV, pp. 339-344.
[30] „ p. 341, Fig. 10. Skizze der Strukturlinien des Fayûm.