Fluvial landforms

Fluvial Landforms in Arid and Semi-Arid Regions... 

Polar and subtropical fronts have shifted southwards in the (geologically) recent past and many regions that are arid today once had a more humid climate. Conversely, many of the present humid regions were much drier in glacial periods, especially between 20,000 and 13,000 BP when aeolian processes influenced land formation more than at present. Mass wasting, fluvial processes and aeolian processes are the most important landform-shaping factors in arid and semi-arid regions. 

Fluvial processes in arid regions produce typical landforms. These are different in high-relief and low-relief areas. 

Contrary to popular concepts, sands do not always dominate arid and semi-arid zones. Aridisols occur on a wide variety of landforms, lithological formations and are of different ages. They are most common on stable land surfaces of Late Pleistocene or greater age in tectonically active deserts where they comprise alluvial fan, alluvial flats or stream terraces. Arid zones also include mountainous terrain with steep slopes (Nettleton and Peterson, 1983). Many arid or semi-arid zones include fluvial and aeolian materials of Pleistocene age. 

Shaw, P.A. Nash, D.J. (1998) Dual mechanisms for the formation of fluvial sil-cretes in the distal reaches of the Okavango Delta Fan, Botswana. Earth Surface Processes and Landforms 23, 705-714. 

The modem landforms of the sea bottom and coasts resulted from a joint action of arid erosion, marine, lacustrine, and fluvial processes, as well as tectonics. 

---