An unconformity exists above the Lake Valley Formation, and appears to include the middle Mississippian through the early Pennsylvanian periods. During the Pennsylvanian and Permian periods, a major deformation created a series of uplifts and intermontane basins. This event is often referred to as the Ancestral Rocky Mountains. Associated with this event is the Magdalena Group, which includes deposits of both marine and non-marine sources. The thickness of these strata is greater than that of all earlier Paleozoic rocks. Above the Magdalena Group is the Red House Formation of packstone and shale, the Nakaye Formation of limestone, the Bar B Formation of interbedded limestone, dolomite, shale, and conglomerate, and the red shale beds of the Abo Formation. All of those strata are Pennsylvanian in age. Above them is thePermian Yeso Formation, which consists of sandstones, siltstone-dolomites, and limestones. The Paleozoic strata are completed by the Meseta Blanca Sandstone.