Located at the junction of 2 physiographic provinces, the Colorado Plateau and Basin and Range, the monument is a geologic treasure. Sedimentary rock layers are relatively undeformed and unobscured by vegetation. Deep canyons, mountains, and lonely buttes testify to the power of geologic forces. Geologic faults range from over 6 million years to much newer faults of only 30,000 years.
Fossils are abundant on the monument. Among these are large numbers of invertebrate fossils and sponges swallowed up by the muddy bottom of a shallow ancient sea.
The monument also contains outstanding biological resources preserved by its remote location and limited travel corridors. The monument is the junction of two physiographic ecoregions: the Mojave Desert and Colorado Plateau. Individually, these regions contain ecosystems extreme to each other, ranging from stark, arid desert to complex, dramatic higher elevation plateaus, tributaries, and rims of the Grand Canyon. The western margin of the Shivwitts Plateau marks the boundary between the Sonoran/Mojave/Great Basin floristic provinces to the west and south, and Colorado Plateau province to the northeast. The intersection of these biomes is a distinctive and remarkable feature.