Present in Elko, White Pine, Lincoln, and Clark Counties. This unit represents mostly Upper Pennsylvanian and Lower Permian rocks that have not otherwise been separated into units Psc or IPMbc. Unit includes unnamed Pennsylvanian and Lower Permian limestone and sandstone beds in Lincoln County, the Bird Spring Formation in Clark County, the Riepe Spring and Ely Limestones (undivided) in White Pine County, and limestone and dolomite rocks not otherwise assigned in Elko County. This unit lies depositionally below unit Psc and above the Ely Limestone (IPMbc) where it is mapped separately. Where unit IPMbc is not mapped separately in southern Nevada, the unit lies directly on Mississippian carbonate (Mc) and in White Pine County it rests on undivided Chainman and Pilot Shales and Joana Limestone (shown as either unit IPMcl or MDcl).