Roadside Geology of Minnesota

You may have heard that Minnesota's ten thousand lakes are the hoofprints of Paul Bunyan's big blue ox, Babe. "Don't you believe it!" writes author Dick Ojakangas. Though the lakes, which formed at the end of the most recent ice age, may be Minnesota's most famous features, the glaciated countryside disguises a much longer history of volcanoes and plate collisions—not surprising when you learn that Minnesota was at the active edge of the fledgling North American continent for several billio...