What do the layers of river sedimentation reveal about the human impact on the Mississippi river system?

River sediments are naturally occurring materials found at the bottom of lakes, seas and rivers. The fast flow of large rivers mean that the sediments are often washed away. Yet, as the following contribution points out, their routes through urban areas and human-altered landscapes mean that they often contain rich pools of data concerning environmental geochemistry. Reading these layers —and acknowledging the complex entanglements of processes that create them—can inform our understanding and response to anthropologic change.