The Pennsylvanian Red House Formation, central Sierra County, New Mexico
— Spencer G. Lucas, Karl Krainer, James E. Barrick, and Justin A. Spielmann

The Lower-Middle Pennsylvanian Red House Formation is the lowermost Pennsylvanian lithostratigraphic unit exposed in central Sierra County, New Mexico. We studied 15 measured stratigraphic sections of the Red House Formation in the Fra Cristobal, Mud Springs, and Caballo Mountains and in the Derry Hills in Sierra County and one section in the Rincon Hills of Doña Ana County. The Red House Formation unconformably overlies rocks that range in age from Proterozoic to Mississippian, is 29-93 m thick, and is overlain conformably by the Middle Pennsylvanian Gray Mesa (= Nakaye) Formation. The Red House Formation is almost equal amounts of gray, green or black shale and limestone (mostly cherty wackestone, nodular wackestone and crinoidal packstone) with subordinate sandstone and conglomerate. We recognize three main lithofacies in the Red House Formation: coarse-grained siliciclastic sediments (sandstone, pebbly sandstone, conglomerate), limestone and shale. We interpret the coarse siliciclastics as tidal and fluvial deposits, the limestones as open, normal marine strata deposited below fair weather wave base but slightly above the storm wave base, and the shale as deposits of the deeper shelf environment below storm wave base. The Derryan Series was originally based on fusulinid biostratigraphy of the Red House Formation, but lithostratigraphic subdivisions of the Derryan are biostratigraphic units that are not mappable or lithostratigraphically useful and can be abandoned. The Red House Formations yields fusulinids, conodonts and brachiopods of Atokan age, and at one location the lowermost Red House Formation is of Morrowan age. Red House Formation conodonts documented here indicate the formation encompasses most of the time commonly assigned to the Atokan Stage. The Red House Formation records the onset of the ancestral Rocky Mountain orogeny in Sierra County and represents deeper marine shelf deposition than the shallow marine and nonmarine deposits of the homotaxial Sandia Formation to the north.