Region 5: The Basin and Range

The Basin and Range region is very rugged, but its soils do not follow any particular pattern coinciding with elevation and slope. Instead, the soils tend to correspond particularly well to the region’s underlying geology. Unsurprisingly, Aridisols—dry, coarse soils formed from the weathering of limestones and carbonate parent material deposited in ancient seas—are the most common soil type in the Basin and Range (Figure 8.22). Due to a lack of precipitation that would leach out soluble minerals, Aridisols contain high concentrations of gypsum, carbonates, and salt, which sometimes solidifies into caliche.

Figure 8.22: An example of an Aridisol soil. These coarse-grained soils are found in desert or arid environments.

Mollisols are common in the Basin and Range, but are almost entirely limited to an area in the central part of the region that contains an igneous geologic substrate. Entisols are the most common soils outside the area occupied by Mollisols, and occur mostly on Permian and late Cretaceous rocks.