Gently rounded or capped by tall peaks, mountains are the planetˇs most striking showpieces. They are also Earthˇs highest land features. Many of these massive, often steep formations are located along the edges of continents. They may form chains, or ranges, that extend for thousands of miles (or kilometers). The principal mountain ranges include the Rocky Mountains and the Andes, which run from North America all the way down through South America,.the Atlas Mountains in Africa, the Himalayas in Asia, and.the Alps in Europe. The longest mountain range in the world is at the bottom of the ocean! It measures more than 40,000 miles (65,000 km) long and reaches several miles (or kilometers) high.