The coal-bearing upper carbonaceous member of the Wepo Formation (Upper Cretaceous) at Black Mesa in northeastern Arizona represents the landward segment of a regressive-transgressive sequence deposited along the southwestern margin of the Western Interior foreland basin. A detailed field investigation of the unit near the northeastern escarpment of Black Mesa resulted in the recognition of six lithofacies (Facies A through F). Facies A includes scour-based, predominantly trough-crossbedded sandstones that are interpreted as distributary, fluvial, and crevasse channel deposits. Facies B consists of rooted, heterolithic sandstone, siltstone, and mudstone sequences that are interpreted as levee deposits. Facies C includes sharp-based, predominantly...