Discovering a Delta's Human History

Notable prehistoric cultural centers include the mound and crescent rings of Poverty Point, Louisiana, a UNESCO World Heritage Site, and Wickliffe Mounds, Kentucky, poised on the bluffs that oversee the confluence of the Ohio and Mississippi Rivers near Cairo, Illinois. Here, avulsion is a key agent that guides the river channel network, causing new lobes of the delta to form while others decline in a process referred to by geologist Harry Roberts at Louisiana State University in Baton Rouge as the "Delta Cycle." [...]the combined record of river activity and human habitation over the past several millennia may contain clues to time-tested strategies for liv- ing with nature in dynamic river-dominated landscapes. Much of the subdelta's land surface has been reworked by human and natural processes-agriculture, parking lots, homes on rare high-elevation land that flanks the channels, and subsidence and erosion of coastal lands outside the walls of artificial levees.