تشكل وادي نهر بردى : دراسة جيومورفولوجية

الملخص EN

Despite the multiplicity of hypotheses designed to explain the formation of the Rabowa Rift Valley, the validity of none of them has been proved; furthermore, no integrated historical perspective has been established of the Barada valley canyon and its development and processes.

The ancient geological, paleo-geophysical and geological evidence, along with the topographical features and characteristics of the valley, that the rift valley was shaped through various stages, where a group of lakes were formed during the Miocene, separated by mountain barriers, and then linked again later forming a transverse drainage network with the beginning of the Pliocene.

With the end and the beginning of the Pleistocene both the river and the valley were formed, followed by the stages of holding the river water during the Quaternary thus forming the system of lakes/rivers, due to renewed activity of cracks which raised their walls at rates beyond the deepening rate of the river.

This was accompanied by the stages of discharge from the river that spilled over and through barriers in a concerted erosion work that varied between vertical and ascending cascading movement.

The river followed multiple ways while forming its valley that varied between overflow, receding and pouring.

It continued.

The succession of lake-river formation continued until the end of the Great Glacial Period, and with the onset of Holocene, river drainage status stabilized to take the river and its valley into its present form.

The valley is characterized by two narrow corridors -gorges- at the beginning and end: Al-Takiya and Al-Rabwah, and two cluses – water gaps- in its middle sector, Ain Al-Faija and Basima.

Its formation was associated with the distribution of faults primarily, geological structures, lateral and vertical pressures and, finally, the effects of climatic changes in the alternating seasons between rainy and dry climates.

The first caused a widening of the lakes and sedimentation, while the latter reduced local base levels and renewed vertical activity within the sediments of the river bed and the gorge.