Stretching more than 3,000 miles across the U.S.-Canadian border, the Rockies are home to bleak alpine tundra zones. They sit up to 14,000 feet above sea level, with temperatures dropping 3.5 degrees Fahrenheit for every thousand feet of elevation. This means that only the hardiest mountain specialists can cope with its savage conditions, like fur-protected mountain goats and the remarkable hoary marmot.