Atlas of a lost world travels in ice age America

Scientists squabble over the locations and dates for human arrival in the New World. The first explorers were few, encampments fleeting. At some point in time, between twenty and forty thousand years ago, sea levels were low enough that a vast land bridge was exposed between Asia and North America-- but was not the only way across. Childs provides an unsparing, vivid, revelatory travelogue through prehistory that traces the arrival of the First People in North America twenty thousand years ago, the megafauna they found here, and the artifacts that enable us to imagine their lives and fates. -- adapted from publisher info