The Graneros Shale is a geologic formation in the United States identified in the Great Plains as well as New Mexico that dates to the Cenomanian Age of the Cretaceous Period.

Hayden originated the scientific names for the series of Cretaceous rocks in the central Great Plains of the North American Continent.

At that time, the early 1860s, Meek and Hayden's "lower Cretaceous" series of the upper Missouri River, Dakota-Benton-Niobrara, was already widely observed from Canada to New Mexico over the Great Plains up to the foothills of the Rocky Mountains.

[6] In southcentral Colorado, southeast of Pueblo, this series expresses topographical patterns that inspired subdivision of the Benton shales.

[4] This group definition was a wide departure from the preceding applications of the early-Cenomanian Graneros name by applying it to late-Albian units.

The late-Albian Skull Creek Shale in the Black Hills is seen with "microfauna identical to" that of the Newcastle,[11] which, in sequence, traces to the Dakota type in the east.

[4][5] As a result, newer reports include the Belle Fourche (Graneros equivalent), Mowry, Newcastle, and Skull Creek within the Dakota Group of this region.

[7] The upper part of the formation contains abundant oyster fossils[1] and the ammonoids Tarrantoceras sellardsi Adkins, Desmoceras, Anthoceras, and Borissiakoceras.