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Geological and Tectonic Influences
Beginning in the Cretaceous Period (136-65 my) an area that encompassed the
present plateau was both inundated by the ancient Tethys Ocean and undergoing
lateral (strike-slip) displacement (Sneh, 1996). During the 60-80 my that
followed, the bedrock profile that we see today evolved as several episodes of
oceanic transgression and recession were depositing multiple layers of
limestone. Today this limestone can be seen both on top and throughout the
stratigraphic record exposed along the steep slopes of the major wadis.
During the Miocene (26-7 my), as the ocean waters receded for the last time (cf.
Guiraud and Bosworth, 1999), tectonic activity began exerting a different force
on the region. No longer moving laterally, the Sinai microplate and Arabian
plate began to move towards each other. Today, we see this plate boundary (Garfunkel,
et al.) along the western edge of the plateau in the Great Rift Valley that
extends nearly 6,000 km from Turkey to East Africa.
The role of faults and fractures along plate boundaries as a major force in the
development and location of river and stream channels has been identified in
several studies (Potter, 1978; Cox, 1989; Burbank, et. al., 1996; and Miller,
et. al., 1996). As a fundamental mechanism in bedrock weathering, fractures
create conduits for surface and groundwater flow (Miller and Dunne, 1996; also
cf. Oberlander, 1965; Aghassy, 1970; and Koons, 1994). The drainage network we
see today, suggests that these processes began to work very early in the
plateau’s tectonically active phase (cf. Ginat, et al., 1998; and Horowitz,
1987).
In response to the compression, which was taking place along the boundary
between the plates, the plateau block began to be displaced vertically. This
vertical displacement triggered the development of transverse faults at several
points along the rift valley.
 Though taking place approximately 20 million years BP, the scars of the faulting
and fracturing are still clearly seen. In the following Landsat 7 image of Wadi
al-Karak, the associated Karak-Fayha Fault (300 km in length) is easily
recognized.
In this image [Figure 4  ] we see Wadi al-Mujib and the fractures and faults
associated with it.
As streams began to develop along the course of the structurally unstable fault
lines, fluvial erosion eventually incised the plateau surface, ushering in the
early stages of the channel forming processes that would result in the formation
of the canyons we see today. However, though geological and tectonic processes
were the major forces defining the course of the plateau’s drainage network, the
role of climate must not be overlooked for its contribution to the success of
these processes.
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