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The term Life Zones describes the changing vegetation found at different elevations. In the monument, where elevation ranges from 4,500 to 8,300 ft., low desert shrub grades into grassy steppe, sage, and pinyon-juniper woodlands, eventually to ponderosa pine at higher elevations, sometimes in a remarkably short distance.

What grows where depends not only on temperature and moisture, determined by elevation, but perhaps more importantly, on soils. Eroded sandstone can create pockets of moisture-holding sandy soil, which can support an abundant mix of grasses, shrubs, and trees.In contrast, the austere gray barrenness of parts of the Kaiparowits Plateau is a result of its mix of Cretaceous-age shales. Unlike wind-shaped, or strem deposited sandstones, these shales were formed in deep, stagnant, oxygen-poor waters of a Cretaceous sea. When erosion re-exposes them to oxygen and to rain, a chemical reaction takes place, which can produce sulfuric acid, salts, and sodium. These chemicals are toxic to most plants except for a few salt-tolerant shrubs, cacti, and forbs such as prince's plume and sego lily.

But the story of soils doesn't end here. Some soils themselves are alive. The inconspicuous dark grayish-brown "crust" which covers perhaps three-quarters of the Colorado Plateau is known as cryptobiotic soil. This delicate crust is made up largely of a filiment-forming blue-green algae whose sticky sheaths cling to soil particles and are interspersed with tiny lichens, green algae and micro-fungi. The crust, easily crushed by automobile or bicycle tires, hiking boots, or animal hooves, plays an important role in holding soil together and slowing down erosion. It also helps provide nutrients to desert plants.