The Naturita Formation is a Cretaceous sedimentary rock unit in western Colorado and eastern Utah, named in 1960 by R. G. Young for Naturita, Colorado. Though not adopted by U.S. Geological Survey authors, the name gained wider use through the Utah Geological Survey as geologists argued these beds were distinct from the classic Dakota of the Great Plains. Lying between older formations and the Mancos Shale, it records changing environments along the advancing Western Interior Cretaceous Seaway, from river channels and floodplains to estuarine, lagoonal, swamp, and coastal-plain settings. Its rocks and fossils preserve a humid coastal landscape and show the formation grew younger southward and westward across Utah as the seaway spread.