Middle and Upper Cambrian rocks and locally up to 90 feet of Lower Ordovician rocks in Central Texas, are here named the Moore Hollow Group. In ascending order, the Moore Hollow Group is composed of the Riley Formation (Hickory Sandstone, Cap Mountain Limestone, and Lion Mountain Sandstone Members) and the Wilberns Formation (Welge Sandstone, Morgan Creek Limestone, Point Peak, and San Saba Members).