Rock Cycle Figure 9-10. No industrialized nation is self-sufficient in mineral resources. Experts are especially concerned about 4 minerals since US has little or no reserves and imports from politically unstable countries. Can we get enough by mining lower-grade ore. Continental shelf and shoreline are significant sources of minerals such as sand, gravel, phosphates, sulfur, copper, and iron.
Most rangeland is grasslands in arid and semiarid areas too dry for crops unless irrigated.
Degradation of rangeland results in decreased livestock production.