Mesquite Mountain, situated on the Colorado River Indian Reservation of westcentral Arizona, records a continuous progression of deformational styles characterized by older, penetrative, ductile fabrics to younger, more localized, brittle structures in the footwall of the regional Whipple-Buckskin-Rawhide detachment system. Rock types consist primarily of deformed migmatitic gneiss, herein termed the Mesquite Gneiss, and minor amounts of deformed intrusive and metasedimentary rocks. Eight phases of deformation are recognized, beginning with D1 development of gneissic compositional layering and intrafolial folding associated with in situ partial melting and injection of the Mesquite Gneiss in Late Cretaceous time.