Major Physical Features of the Western United States

The American West is defined by dramatic geology at continental scale. Five iconic features:

1. Rocky Mountains

3,000+ miles from BC/Yukon to New Mexico. Highest: Mount Elbert (14,440 ft). Continental Divide follows crest. Subranges: Front Range, Sawatch, San Juans, Tetons, Wind Rivers, Beartooths, Bitterroots, Rockies (Canada). Headwaters: Colorado, Columbia, Missouri, Arkansas, Rio Grande.

2. Great Plains

Broad eastward-sloping plateau from Rockies to ~98th meridian. Shortgrass/mixedgrass/tallgrass prairies (now mostly cropland). Ogallala Aquifer underneath. Bison, pronghorn, prairie dogs, grassland birds. Wheat, corn, sorghum, cattle.

3. Sonoran Desert

120,000 sq mi (AZ, CA, MX Sonora, Baja). Hottest North American desert but biologically richest—two rainy seasons. Saguaro cactus (indicator species), organ pipe, cholla, palo verde, ironwood. Gila monster, roadrunner, desert tortoise. Phoenix, Tucson, Hermosillo within.

4. Pacific Ocean & Coast

Largest ocean (63M sq mi). West Coast: Cascadia subduction zone (volcanoes, quakes), Coast Ranges, Central Valley (CA), Transverse Ranges, Peninsular Ranges. Upwelling → productive fisheries. Kelp forests, estuaries, marine mammals.

5. Sierra Nevada

400-mile granitic batholith (CA, minor NV). Highest contiguous US peak: Mount Whitney (14,505 ft). Yosemite, Sequoia, Kings Canyon NPs. Lake Tahoe (alpine). Giant sequoias (largest trees). Rain shadow creates Great Basin desert east.

Bonus: Basin and Range

NV, UT, AZ, OR, ID, CA — alternating mountain ranges and valleys (horsts/grabens). Death Valley (lowest, hottest), Great Salt Lake, playas, metamorphic core complexes.

Unifying Theme

Tectonics: Pacific Plate interactions (subduction, transform, extension) built the West. Water scarcity (except PNW) shapes life. Public land (BLM, USFS, NPS) = ~50% of West — unique governance.