The word bajada means “slope” in Spanish and is taken from the verb bajar, to descend. A bajada comprises a sequence of alluvial fans spreading into a desert valley at a shallow angle from a series of steep side canyons. In the Cabeza Prieta National Wildlife Refuge, a remote part of the Sonoran Desert west of Tucson, Arizona, each alluvial fan suggests the flaring pleats of a starched apron. The overall convexity of each apron, together with the pattern of their abutment, gives the long bajada its characteristic undulating surface, which may run for miles around the base of a mountain. Craig Childs, writing about these outwash plains of flash flood–borne debris in The Secret Knowledge of Water, notes that this deceptively still landscape is “not idle,” that the mountains are “bitterly seared. Rising a couple of thousand feet off the floor [of a Cabeza Prieta valley], they are offset by swaths of bulged, rolling desert bajadas that take days to cross.”

Terry Tempest Williams