Many scientists believe that the first people arrived in North America during the last Ice Age. At the start of the Ice Age, Earth’s climate became intensely cold. Large amounts of water froze into huge, moving sheets of ice called glaciers. As a result, ocean levels dropped more than 300 feet lower than they are today. When the sea level fell, a land bridge between northeastern Asia and present-day Alaska was exposed. Geographers call this strip of land the Bering Land Bridge. Although no one knows exactly when or how people crossed into North America, evidence suggests that people called Paleo-Indians crossed this bridge into Alaska between 38,000 and 10,000 BC. Which feature of the Ice Age allowed Paleo-Indians to migrate to the Americas?