Pictured Cliffs Formation
The Pictured Cliffs Formation is a Campanian geologic formation in the San Juan Basin of New Mexico. Dinosaur remains are among the fossils that have been recovered from the formation, although none have yet been referred to a specific genus.
Description
The formation consists of yellowish-gray to grayish-orange cliff-forming sandstone. The upper beds are massive and crossbedded, consisting of well-sorted, fine-grained, friable sandstone. The lower beds are alternating thin beds of sandstone and light- to dark-gray silty shale. The upper part of the shale beds contains up to of discontinuous ironstone beds. The total thickness is about. The formation is transitional with both the underlying Lewis Shale and the overlying Fruitland Formation.The formation is interpreted as a marine littoral formation deposited during the final regression of the Western Interior Seaway from the San Juan Basin, with recognizable delta-front and barrier island facies. The regression was interrupted by at least three brief transgressions that produced tongues of the upper Pictured Cliff Sandstone in the northern San Juan Basin.