Upper Cenozoic Palomas Formation of south-central New Mexico
— Richard P. Lozinsky and John W. Hawley

Upper Santa Fe Group deposits occurring in the Palomas, Engle, and San Marcial Basins of the southern Rio Grande rift are here named the Palomas Formation. The term "Palomas gravel" was first applied to Plio-Pleistocene basin fill in the region in 1907; however, the formation has never been formally defined. It consists mainly of alluvial-fan and coalescent-fan deposits (piedmont facies) and ancestral Rio Grande fluvial deposits (axial-river facies). Maximum thicknesses range from 100 to locally more than 130 m. Formation deposition probably began prior to 5 my and continued until 400,000-500,000 years ago. The formation can be distinguished from other upper Santa Fe Group deposits by its extensive piedmont facies and relatively  narrow belt of axial-river deposits. Older Santa Fe units (Miocene–latest Oligocene), which do not contain axial-river facies, occupy remnants of early rift basins that predate development of the present system of basins and uplifts.