Abstract This two-day excursion will travel to the Yampa coal field located in parts of Moffat, Rio Blanco, and Routt Counties, northwestern Colorado. The excursion will visit classic regression/transgression successions in the Upper Cretaceous coal-bearing Mesaverde Group, which was deposited along the western edge of the Cretaceous seaway. It includes visits to inactive and active mine sites where past and current mining practices will be discussed. This guide summarizes the stratigraphy, sedimentology, and coal geology of the Yampa coal field. The trip will emphasize the depositional setting, sedimentology, and quality of the Upper Cretaceous coals and coal-bearing strata of the Mesaverde Group.