hich played an important part in the irrigation schemes of the
Pharaohs. The water of el-Kerun is brackish, though derived from the
Nile, which has at all seasons a much higher level. It is bounded on
the north by the Libyan Desert, above which rises a bold range of
mountains; and it has a strange and picturesque wildness. Near the
lake are several sites of ancient towns, and the temple called
Kasr-Karun, dating from Roman times, distinguishes the most important
of these. South-west of the Fayum is the Wadi Rayan, a large and deep
depression, utilizable in modern schemes for re-creating the Lake of
Moeris (q.v.).

[Illustration: Nile Delta.]

_The Desert Plateaus._--From the southern borders of Egypt to the
Delta in the north, the desert plateaus extend on either side of the
Nile valley. The eastern region, between the Nile and the Red Sea,
varies in width from 90 to 350 m. and is known in its northern part as
the Arabian Desert. The western region has no natural barrier for many
hundreds of miles; it is part of the vast Sahara. On its eastern edge,
a few miles west of Cairo, stand the great pyramids (q.v.) of Gizeh or
Giza. North of Assuan it is called the Libyan Desert. In the north the
desert plateaus are comparatively low, but from Cairo southwards they
rise to 1000 and even 1500 ft. above sea-level. Formed mostly of
horizontal strata of varying hardness, they present a series of
terraces of minor plateaus, rising one above the other, and
intersected by small ravines worn by the occasional rainstorms which
burst in their neighbourhood. The weathering of this desert area is
probably fairly rapid, and the agents at work are principally the
rapid heating and cooling of the rocks by day and night, and the
erosive action of sand-laden wind on the softer layers; these, aided
by the occasional rain, are ceaselessly at work, and produce the
successive plateaus, dotted with small isolated hills and cut up by
valleys (wadis) which occasionally become deep ravines, thus forming
the principal type of scenery of these deserts. From this it will be
seen that the desert in Egypt is mainly a rock desert, where the
surface is formed of disintegrated rock, the finer particles of which
have been carried away by the wind; and east of the Nile this is
almost exclusively the case. Here the desert meets the line of
mountains which runs parallel to the Red Sea and the