Mississippi River

Named for the river, not the state: the reference is to limestone bluffs a long way upstream of Mississippi.

Alexander Winchell proposed the name in 1870 for the thick lower Carboniferous limestones exposed along the upper Mississippi valley in Iowa, Illinois and Missouri. Henry Shaler Williams added the Pennsylvanian above it in 1891. The river's own name comes from Ojibwe misi-ziibi, great river, so a period of earth history is ultimately labeled in an Algonquian language.