32
E. A. Zaghloul
2.2 The Scarp Face
The scarp face of the plateau extends in an undulating line running in an east – west
direction for a distance of about 80 km. At Mawhub area, the scarp face extends
80 km. in a northwest direction. The average height of the scarp is 500 m. above
sea level and the average difference in elevation between the scarp and the ground
level of the depression is 400 m. The shale sequences of the Dakhla Formation with
variable thickness from 100 m. to 200 m. cover at least 2/3 of the scarp face which are
overlain by a hard limestone unit. Along the edge of the scarp face, the limestone also
varies in thickness from 20 m. to 50 m. and whenever the shale section increase in
thickness, the limestone unit decreases and vice versa. The scarp face is characterized
by steeper cliffs which are dissected by joints, cracks and fissures.
The Scarp face extends more than 250 km in a WNW—ESE direction from
Teneida tn the east to Abu Minqar to the west and has a irregular outline. The elevation
of the plateau surface ranges from 400 m (amsl) and increased to be about 580 m
(amsl) due to the northeast direction. It is marked by a number of promontories in
which the most important one is located east of Gabal Giftan, al-Qasr and northeast
of Balat. The scarp face is made of shale, clay, mudstone, limestone and chalky
limestone of Upper Cretaceous and Paleocene ages.
The drainage system crossing the area is very irregular and running along the joint
planes of the hard limestone and is not well developed in the scarp face.
2.3 The Dakhla Depression
The Dakhla depression covers an area about 1200 km
2 and extends from Teneida
in the east to West Mawhub in the west. It is excavated in the Nubian and Duwi
Formations. The depression opens toward south where its floor gradually merges
southward into the Nubian Sandstone plain (Brooks 1993). The floor consists mainly
of red clays of the Quseir Formation, and is covered in some localities by alluvium
deposits that are partially cultivated. Sand dunes frequently cover the scarp face in
various localities, as well as areas in the depression of the oasis. The major sand
dunes form a north-northwest/south- southeast trend extending to the west of Qaret
Mawhub (Edmonstone).
Gabal Edmonstone is a single isolated hill in the whole depression of Dakhla. It is
a detached portion of the retreated plateau and occurs about 18 km west of al-Qasr.
This conspicuous hill has a height of about 465 m (amsl) and about 300 m above the
depression plain (Brooks 1993).
On the other hand, Gabal Edmonstone divided the Dakhla Basin into two subbasin, i.e., Mut sub-basin for 170 km in length in the east (Fig. 3) and the West
Mawhub sub-basin for about 80 km. in length due to the west.
The depression is covered by clay, sandstone and silt downwashes from the
scarp face and the pediment below. These deposits form extensive lake beds (Playa
E. A. Zaghloul
2.2 The Scarp Face
The scarp face of the plateau extends in an undulating line running in an east – west
direction for a distance of about 80 km. At Mawhub area, the scarp face extends
80 km. in a northwest direction. The average height of the scarp is 500 m. above
sea level and the average difference in elevation between the scarp and the ground
level of the depression is 400 m. The shale sequences of the Dakhla Formation with
variable thickness from 100 m. to 200 m. cover at least 2/3 of the scarp face which are
overlain by a hard limestone unit. Along the edge of the scarp face, the limestone also
varies in thickness from 20 m. to 50 m. and whenever the shale section increase in
thickness, the limestone unit decreases and vice versa. The scarp face is characterized
by steeper cliffs which are dissected by joints, cracks and fissures.
The Scarp face extends more than 250 km in a WNW—ESE direction from
Teneida tn the east to Abu Minqar to the west and has a irregular outline. The elevation
of the plateau surface ranges from 400 m (amsl) and increased to be about 580 m
(amsl) due to the northeast direction. It is marked by a number of promontories in
which the most important one is located east of Gabal Giftan, al-Qasr and northeast
of Balat. The scarp face is made of shale, clay, mudstone, limestone and chalky
limestone of Upper Cretaceous and Paleocene ages.
The drainage system crossing the area is very irregular and running along the joint
planes of the hard limestone and is not well developed in the scarp face.
2.3 The Dakhla Depression
The Dakhla depression covers an area about 1200 km
2 and extends from Teneida
in the east to West Mawhub in the west. It is excavated in the Nubian and Duwi
Formations. The depression opens toward south where its floor gradually merges
southward into the Nubian Sandstone plain (Brooks 1993). The floor consists mainly
of red clays of the Quseir Formation, and is covered in some localities by alluvium
deposits that are partially cultivated. Sand dunes frequently cover the scarp face in
various localities, as well as areas in the depression of the oasis. The major sand
dunes form a north-northwest/south- southeast trend extending to the west of Qaret
Mawhub (Edmonstone).
Gabal Edmonstone is a single isolated hill in the whole depression of Dakhla. It is
a detached portion of the retreated plateau and occurs about 18 km west of al-Qasr.
This conspicuous hill has a height of about 465 m (amsl) and about 300 m above the
depression plain (Brooks 1993).
On the other hand, Gabal Edmonstone divided the Dakhla Basin into two subbasin, i.e., Mut sub-basin for 170 km in length in the east (Fig. 3) and the West
Mawhub sub-basin for about 80 km. in length due to the west.
The depression is covered by clay, sandstone and silt downwashes from the
scarp face and the pediment below. These deposits form extensive lake beds (Playa