During the Archaic Period of habitation on Delmarva, from 6500 to 3000 B.C., climate warming brought the development of oak, hemlock, and pine forests as Delaware Bay expanded over the coastal plain and formed brackish water tidal marshes along its edges, when sea levels were 60 feet lower than today. Rising seas also created inland swamps, while deer, turkey, and other wild game proliferated. Native people lived in small, mobile groups and set up camps along coastal marshes, rivers, swamps, and other waterways to hunt and gather from rich seasonal fish, game, and plant resources. They made fishing nets from cordage woven from various plant fibers and developed diverse specialized tools for harvesting plant and animal resources, including the atlatl, or spear-thrower, which became a key weapon for hunting game animals.