In the area of Nubia it is very
narrow. At Aswan, not far north of the First Cataract, it is only about 1 km
wide and there is practically no alluvial plain. On both sides of the valley there
are layers of reddish-brownish sandstone, and granite blocks and inselbergs
come to the surface. Between Isna and Sohag the river starts meandering in
the gradually widening valley. In Middle Egypt the Nile valley is 15–20 km
wide and the present river bed is situated close to the steep eastern rim of
the valley. In many places Pleistocene Nile terraces can be found between
the Holocene river plain and the scarps of the valley sides, which consist of
Tertiary and Cretaceous layers. Unlike the valley bed, which consists of the
fertile black soils, the older Nile terraces are formed by gravel and coarse
sands. The most expansive Pleistocene Nile terrace is situated in the Kom
Ombo plain, where in the 1960s many Nubians who had lost their land in
the south when the Sadd el-Ali was constructed were resettled.
El-Faiyum Oasis lies in a former part of the Nile valley, later cut off from
the main valley. Today it is fed with Nile water through Bahr Yousif, a Nile
arm. The oasis covers an area of 1,800 km2
 and drains off into Lake Qarun,
which has grown considerably during recent decades owing to increasing
irrigation and drainage