Geomorphology of Dakhla Depression
55
Fig. 12 Classical view of the Escarpment, Bir El Gabal area
The geological succession in the scarp-cliffs is decisive in the rate of slope retreatment. The lower formation is composed of shale and friable sand while the upper one
is limestone (see Fig. 12). There are different pieces of evidence for the paleo-karst in
the upper formations. Some of these karstified rocks already collapsed on the lower
slope sector. The pediment zone varies from 3 to 6 km.
The scarp is topped by Limestone caps, which are vertical small walls vary in
thickness between 20 and 30 m and well-seen from any point in the depression of
Dakhla. Since caps are dissected by vertical joint wearing this limestone layer into
semi-independent blocks (see Fig. 13), the non-trained eyes might mislead them with
a row of high old white buildings (Fig. 14).
The so-called Libyan plateau behind the scarp line of Dakhla (above 500 m) is
a vast upland (25,000 km
2 ), composed of different landforms, the most prominent
are yardang (Kharafesh in local naming) in addition to terraces-like ridges on the
transitional zone between scarp and tabular lands. Classical geomorphic features are
abundant along the scarp, especially V-shaped incised valleys, mass movements, and
falling dunes.
Brooks (1993) found that karstification on the plateau zone is dominated by an
extensive field of yardangs and rolling topography which resemble the same degraded
karst, possibly of ‘cockpit’ form of paleokarst described by El-Aref above Bahareya
Oasis (El-Aref et al. 1987).
Dakhla scarp could be classified from east to west into four sections:
Abu Tartur which is a semi-circular arc representing the transitional sector that
connects together the two depressions of Kharga and Dakhla. Abu Tartur is a semiattached rounded plateau. The perimeter is 190 km and the total area is 3000 km
2 . It
overlooks the floor of Dakhala Depression in two inner close basins: EL-Zayyat and
Abu El Egl. Wadi El-Battikh (valley of watermelon) is the largest one draining the
escarpment and even has a typical small alluvial fan. The term “El-Battikh” is used
55
Fig. 12 Classical view of the Escarpment, Bir El Gabal area
The geological succession in the scarp-cliffs is decisive in the rate of slope retreatment. The lower formation is composed of shale and friable sand while the upper one
is limestone (see Fig. 12). There are different pieces of evidence for the paleo-karst in
the upper formations. Some of these karstified rocks already collapsed on the lower
slope sector. The pediment zone varies from 3 to 6 km.
The scarp is topped by Limestone caps, which are vertical small walls vary in
thickness between 20 and 30 m and well-seen from any point in the depression of
Dakhla. Since caps are dissected by vertical joint wearing this limestone layer into
semi-independent blocks (see Fig. 13), the non-trained eyes might mislead them with
a row of high old white buildings (Fig. 14).
The so-called Libyan plateau behind the scarp line of Dakhla (above 500 m) is
a vast upland (25,000 km
2 ), composed of different landforms, the most prominent
are yardang (Kharafesh in local naming) in addition to terraces-like ridges on the
transitional zone between scarp and tabular lands. Classical geomorphic features are
abundant along the scarp, especially V-shaped incised valleys, mass movements, and
falling dunes.
Brooks (1993) found that karstification on the plateau zone is dominated by an
extensive field of yardangs and rolling topography which resemble the same degraded
karst, possibly of ‘cockpit’ form of paleokarst described by El-Aref above Bahareya
Oasis (El-Aref et al. 1987).
Dakhla scarp could be classified from east to west into four sections:
Abu Tartur which is a semi-circular arc representing the transitional sector that
connects together the two depressions of Kharga and Dakhla. Abu Tartur is a semiattached rounded plateau. The perimeter is 190 km and the total area is 3000 km
2 . It
overlooks the floor of Dakhala Depression in two inner close basins: EL-Zayyat and
Abu El Egl. Wadi El-Battikh (valley of watermelon) is the largest one draining the
escarpment and even has a typical small alluvial fan. The term “El-Battikh” is used