People arrived in North America from Asia more than 14,000 years ago at the end of the last Ice Age, when glaciers lowered sea level and exposed a wide land bridge where the Bering Sea is today. In Illinois, the climate was cooler and wetter than today, with a shorter growing season and more winter snow. Forests of spruce and black ash were home to mastodon, stag moose, giant ground sloth, and white-tailed deer. Paleoindians lived in small family groups, hunting, fishing, and gathering plant foods while moving often in search of food and other resources. They left little trace of their lives beyond a few spear points, knives, and other stone tools, shaping spear points and knives by flaking a piece of chert with a bone or stone hammer. The groove at the bottom of the point made it easier to fasten it to a wooden spear shaft or a knife handle. In 1980, archaeologists unearthed the pelvis of a mastodon near Kimmswick, Missouri, and found a Paleoindian spear point lying next to the bone, evidence of mastodon hunting.