The Mancos Shale is a thin grey shaley unit near Show Low, and is a deeper water marine unit consisting of three thin intertongueing formations, the Clay Mesa Shale, Paguate Sandstone, and the Whitewater Arroyo shale units. The three units are not easily separable in the field, and will be treated as one here. The unit consists of shales, limestones and sandstones, with baseball to 1m sized concretions surrounding a core of a bit of shell or plant material. In many localities, we often found large barite/calcite accicular nodules near the top of the unit, just under the base of the Twowells Sandstone. The Clay Mesa/Whitewater Arroyo unit can contain a locally rich fossil assemblage of oysters, cephalopods, gastropods, sharks teeth and formainifera.