consists of shallow marine, open marine, and carbonate shelf deposits. This unit has yielded over 50 million barrels of oil in Colorado and Utah. The Molas Formation consists of three members: The Coalbank Hill Member is a residual soil deposit that consists of red to brown siltstones, cherts, and conglomerates. It may rest conformably over the Leadville Limestone or unconformably over the Ouray Formation. The middle member consists of red-brown siltstones, sandstones, and conglomerates reflective of stream deposits. This unit rests unconformably over the Coalbank Hill Member. The upper member is similar to the preceding middle member, but also contains fossiliferous limestone indicative of a transgressing shoreline. The Log Springs Formation is stratigraphically equivalent to the Molas Formation and lithologically similar to the Coalbank and middle members of the Molas Formation. Pennsylvanian The Pinkerton Trail (north) and the Sandia (south) formations consists of grey argillaceous or fossiliferous limestone and calcareous shale beds. The units were deposited during a southwest to westward transgressing sea. The Paradox Formation contains complex, cyclic evaporite deposits of alternating porous salts and non-porous shales/limestones. These work as excellent stratigraphic traps for hydrocarbons. The Honaker Trail Formation consists of basal open marine limestones and dolomites overlain by arkosic sandstones from the northern Uncompahgre highland. The early 1,400' thick unit conformably overlies the Paradox Formation. The southern equivalent of the Paradox and Honaker Formations is the Madera Group. Its lower section consists of grey shales and limestones of the Gray Mesa Formation that grades into the upper, acrostic sandstone-rich Atrasado Formation. Total thickness is nearly 1,300'. The transition from Pennsylvanian marine units to Permian continental units is represented by the Rico Formation. It consists of conglomerates and arkosic sandstones interbedded with marine shales and fossiliferous limestones. Permian The Cutler Group consists of alluvial fan deposits from north and northeastern sources (e.g., the Uncompahgre and the San Luis highlands). Deposits include arkosic sandstones, conglomerates, and minor siltstones and mudstones. The Cutler Group is divided into several formations: The Halgaito Formation consists of alternating marginal marine and fluvial sediments, and it conformably overlies the Rico Formation. The Cedar Mesa Sandstone varies with location, but contains evaporite, fluvial, tidal-flat, and sabkha facies. The Organ Rock Formation contains siltstones and sandstones from coastal-plain and fluvial deposits sourced from the north. The De Chelly Sandstone consists of sandstones of eolian deposits. The unit is broken into lower and upper members based on sediment