division of Pennsylvanian rocks and time in the south central and southwestern U.S., especially Texas (the Pennsylvanian Period, roughly equivalent to the Upper Carboniferous, began about 318,000,000 years ago and lasted about 19,000,000 years). The Lampasan Series is correlated with the Atokan Series (a standard division of the Lower Pennsylvanian in the U.S.), overlies the Bendian Series, and underlies the Strawn Series. Two major divisions of the Lampasan are recognized: the lower Big Spring Group and the Smithwick Group.