Geoscience Reference
In-Depth Information
Figure 12.6
Schematic diagrams to highlight the contrasting behavioural tendencies of rivers in southern Africa. (a) Ingrown
meander bend along the mixed bedrock-alluvial middle Orange River, South Africa. On the inner bend, gently sloping alluvial sheets
form as a result of point bar deposition during lateral migration and minor vertical incision of the channel bed, while distinct
scarps separating these sheets result from phases of more rapid vertical incision during the headward migration of knickpoints. On
the outer bend, steep cutbanks are formed in tillite (from McCarthy and Tooth, 2004, reproduced by permission of Schweizerbart
and Borntraeger Science Publishers, http://www.borntraeger-cramer.de). (b) Failing channel in the wetlands of the Okavango
Delta, Botswana. Channel aggradation by bedload sand leads to a gradual rise of local water levels in and around the channel,
