Sheets of darker colors seem to hang like curtains on the faces of many canyon walls in arid environments. The towering, buff-colored sandstone cliffs of Canyon de Chelly in northeastern Arizona, for example, which are famously revealed in the photographs of Edward Curtis and others, seem draped with umber hangings. The patterns of color on such tapestry walls record the patterns of water spills and seeps that periodically irrigate the walls with snowmelt and storm runoff. When the water evaporates, it leaves behind microscopic deposits of the minerals it once contained. These minerals gradually oxidize, perhaps as a result of the metabolic activity of bacteria that colonize the rock, and the buildup of oxides, rusty to brown where iron is dominant, accounts for the contrasting colors of the tapestry. Vegetation can also produce the impression of a tapestry hanging on the sheer face of a cliff or canyon wall. Vesey’s Paradise in the Grand Canyon, for example, is fed by a spring that pours from a seam high on the side of the lower canyon. A jungle of green seems to hang from the mouth of the spring, and, notwithstanding that much of this vegetation consists of nettle and poison ivy, such a profusion of green in a sere and sun-blasted environment gives an impression of a kind of Eden.