Fruitland Formation the Colorado-New Mexico state line, and is one of the most productive areas for coalbed methane in the United States. The Fruitland is underlain by the Pictured Cliffs Sandstone, and overlain by the more recent Kirtland Formation. The sequence of rocks represents the final filling of the Cretaceous seaway. The underlying Pictured Cliffs is a marginal marine sandstone, deposited in an environment similar to offshore barrier islands of the southeast United States. As the seaway retreated, the Pictured Cliffs was covered by the Fruitland Formation, which was deposited in near-shore swampy lowlands. The formation is dated to the late Campanian
Straight Cliffs Formation are known to contain marine invertebrate fauna because the Smoky Hollow and Drip Tank Member were deposited in terrestrial settings. The Tibbet Canyon Member was initially dated based a middle Turonian index fossil "Inoceramus howelli" which indicates the "Prionocyclus hyatti" ammonite zone. A variety of invertebrate fossils have been found in the John Henry Member including the ammonite "Baculites codyensis" and the bivalve "Endocostea baltica". Analysis of foraminifera and ostracods has helped refine depositional environment interpretations for a variety of shallow marine sub-environments such as lagoons, bays, and estuaries Vertebrate fossils have been found throughout the Straight Cliffs Formation. The