The Turner River Site, in the Ten Thousand Islands region of Everglades National Park near Chokoloskee Island, is a large prehistoric shell works covering about 30 acres with at least 30 closely spaced mounds. Known to archaeologists by 1900 and identified in 1918 as important to science, it became the first professionally excavated site in the Ten Thousand Islands in 1955. William H. Sears found mostly clean oyster-shell mounds built on submerged mud flats, with midden material and Glades I and II potsherds indicating a village that shifted toward the river as the mounds accumulated. Occupied roughly from 200 or 100 BCE to 800 or 900 CE, the site helped establish the region as a major prehistoric population center.