Maquoketa Formation  search
BTChronostratigraphic Units
 .Phanerozoic
 ..Paleozoic
 ...Ordovician
 ....Upper Ordovician
 .....Maquoketa Formation
RTIowa
 Missouri
 Illinois
 Wisconsin
 Minnesota
SNIn Missouri, it is typically thin laminated shale interbedded with shaly limestone members. W Illinois, E Iowa, S Minnesota, E Missouri, and SW Wisconsin.