Geoscience Reference
In-Depth Information
Figure 20.2. Amphitheatre headwall created by differential erosion, Grand Canyon,
Arizona.
1972
; Tchakerian,
1995
). The role of the sporadic desert sheet floods and of running
water more generally was quickly recognised in even the most arid of landscapes,
leading to the recognition of ancient river systems on the Colorado Plateau and else-
where (Luchitta et al.,
2011
). Then came the recognition of a suite of desert landforms,
including pediments, or low-angle rock-cut slopes, at the foot of mountains in Arizona,
alluvial fans in the Mojave Desert and salt lakes, or playas, in Utah.
Efforts to account for the differences between landforms deemed typical of humid
regions and those thought to be characteristic of deserts led to prolonged debates
over whether slopes in deserts retreated parallel to themselves to form low-angle
slopes of coalescent pediments termed pediplains or whether they were worn down
