Physiographic Province | Surficial Geologic Material | Percentage of MFR Zones (%) |
Southern Rocky Mountains | ||
Glacial till sediments, mostly sandy, thin | 2 | |
Residual materials developed in sedimentary rocks, discontinuous | 8 | |
Alluvial sediments, thick | 29 | |
Residual materials developed in igneous and metamorphic rocks | 61 | |
Basin and Range | ||
Eolian sediments, mostly dune sand, thin | 7 | |
Other surficial materials | 11 | |
Residual materials developed in igneous and metamorphic rocks | 14 | |
Alluvial sediments, thick | 68 | |
All MFR Zones | ||
Eolian sediments, mostly dune sand, thin | 6 | |
Other surficial materials | 10 | |
Residual materials developed in igneous and metamorphic rocks | 22 | |
Alluvial sediments, thick | 62 |