The rugged Rockies—site of North America’s Continental Divide—were carved out by huge glaciers during successive ice ages. Readers of this “Mountains Around the World” series will discover that the Rockies are sometimes called the backbone of North America, stretching from British Columbia in Canada to New Mexico in the United States. Formed seventy-five million years ago, this chain controls climate over a wide area and contains glacial lakes, deep valleys, and mighty peaks like Mount Elbert in Colorado.