Sequence stratigraphy of the upper cretaceous upper Williams Fork Formation, Piceance Basin, northwest Colorado, and its contribution to the basin-centered gas accumulation

The upper Williams Fork Formation is part of the Williams Fork Formation in the Piceance Basin. The upper Williams Fork Formation comprises of the upper Williams Fork shale, upper Williams Fork sandstone, Price Coal, WF 600, Lion Canyon Sandstone and the Goff and Lion Canyon Coal intervals. These units, deposited as part of a third-order depositional sequence in a coastal plain setting on the margin of to the Late Cretaceous Interior Seaway. This interval records deposition from the late lowstand systems tract to the highstand systems tract during the late Campanian to early Maastrichtian in the Piceance Basin.;These lithofacies and depositional sequences are major controls on the basin-centered gas system present in the Williams Fork Formation in the Piceance Basin.