Sherwood Island State Park land formed about 17,500 years ago as the last Ice Age glacier melted and left behind sand, pebbles, and rocks, creating low-lying land beside what was then a broad, shallow fresh water lake in the place of Long Island Sound. As the climate warmed, Native Americans of the Paleo Period moved into the area from the south and west and hunted big game such as caribou with stone-tipped spears thrown from shoulder height. As sea level rose and Long Island Sound became tidal, marine resources became important during the Archaic Period, and by 5,000 years ago clams, oysters, and scallops were harvested from marshes and shallow waters along the sound; the meat was eaten or smoked and dried for winter and early spring, and discarded shells and other trash formed shell middens. About 3,000 years ago, during the Woodland Period, Native Americans began making hand-molded pottery from local clays, firing the vessels for storage and cooking, and archaeological excavations at Sherwood Island have recovered potsherds showing that people camped and cooked there. Beginning around 1,000 years ago, Native Americans cultivated maize, beans, squash, and tobacco, and made small, thin triangular stone points for use with a bow and arrow. After Europeans arrived, Native Americans of the Contact Period traded furs and maize for metal objects such as copper kettles and brass pots, which they cut up and hammered into arrowheads. Along this coast, the early Contact Period people were the Pequonnocks, part of the larger Paugussett Nation, whose territory extended from the Norwalk area south of Sherwood Island State Park north to what is now the New Haven area and also inland along local rivers reached by canoe. When Europeans first settled here in the 1630s, the local Pequonnocks had already cleared many shoreline trees to plant the three sisters of corn, beans, and squash. An ulu, a half-moon-shaped stone knife used by Native American women to process large numbers of fish for drying and cooking, was found at Sherwood Island State Park and provides scientific evidence of a traditional activity that often involved whole families over an extended time.