A mountain is a large landform that stretches above the surrounding land in a limited area, usually in the form of a peak. A mountain is generally steeper than a hill. Mountains are formed through tectonic forces or volcanism. These forces can locally raise the surface of the earth by over 10,000 feet (3,000 m). Mountains erode slowly through the action of rivers, weather conditions, and glaciers. A few mountains are isolated summits, but most occur in huge mountain ranges.
High elevations on mountains produce colder climates than at sea level. These colder climates strongly affect the ecosystem of mountains: different elevations have different plants and animals. Because of the less hospitable terrain and climate, mountains tend to be used less for agriculture and more for resource extraction and recreation, such as mountain climbing.
The highest mountain on Earth is Mount Everest in the Himalayas of Asia, whose summit is 8,849.868 m (29,035 ft) above mean sea level. The highest known mountain on any planet in the Solar System is Olympus Mons on Mars at 21,171 m (69,459 ft).
A train is a form of rail transport consisting of a series of vehicles propelled along a rail track to transport cargo or passengers. Motive power is provided by a separate locomotive or individual motors in self-propelled multiple units. Although historically steam propulsion dominated, the most common modern forms are diesel and electric locomotives, the latter supplied by overhead wires or additional rails. Other energy sources include horses, rope or wire, gravity, pneumatics, batteries, and gas turbines. Train tracks usually consists of two, three or four rails, with a limited number of monorails and maglev guideways in the mix. The word ‘train’ comes from the Old French trahiner, from the Latin trahere ‘pull, draw’.