Millions of years ago, the North American continent was dragged over the world's largest continental hotspot (a hug column of molten rock rising from the earth's interior), tracing a 5 mile wide, 500 mile long path northeastward across Idaho and generating huge volcanic eruptions and earthquakes. The hotspot lifted the Yellowstone Plateau to more than 7000 feet and pushed the Northern Rockies to new heights. This book is the story of those events and how the landscape of the two great national parks was shaped by earthquakes, volcanoes, geysers and, in the uplifted Rocky Mountains, mountain glaciers. The story is also a 'window' into the earth's interior, revealing the dynamic processes within.