Environmental Engineering Reference
In-Depth Information
dams for reservoirs. Mass movement processes also contribute to the chaotic landscape of
badlands. If the marls and clays are able to develop vertical cracks, the channels will take
on a rectangular cross-section, with vertical walls and a flat valley floor, which get larger
through the collapse of the walls of marl.
Badlands seem to have various causes. Those of the Great Plains, Utah and Alberta in
North America are natural, whereas those of California, Arizona and Georgia are
attributed to the impact of European farming practices. Badlands give the appearance of
extremely rapid rates of erosion, with fresh gullies and actively eroding slopes (Plates 1
and 2), but erosion rates are extremely variable. In the Ebro valley of north-east Spain
erosion rates of 15-20 mm per year have been measured. However, in the Guadix
badlands of the Spanish Sierra Nevada, famous for its cliff houses or troglodyte
dwellings, erosion rates are very slow. From the evidence of 4000 year old archaeological
structures, the badlands here appear to have suffered little erosion during this time, with
rates of only about 0·01 mm per year.
Plate 2
The badland scenery of the 'desert' of Tabernas in Almería
province, south-east Spain. A semi-arid climate combined with a
rock type of silty clay marls are the dominant factors.
Photo: Ken Atkinson.
