Mountain

Lore & Background

Mountains are formed through tectonic forces, erosion, or volcanism, which act on time scales of up to tens of millions of years. Once mountain building ceases, mountains are slowly leveled through the action of weathering, through slumping and other forms of mass wasting, as well as through erosion by rivers and glaciers. High elevations on mountains produce colder climates than at sea level at similar latitude. These colder climates strongly affect the ecosystems 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, such as mining and logging, along with recreation, such as mountain climbing and skiing.

In Their Own Story

The wind howls across the jagged peaks, carrying ice crystals that sting like needles. Rayman grips his fists, feeling the cold seep through his fingers as he stares down a narrow ledge. Below, a massive boulder begins to shift, sending a tremor through the snowpack. With no time to hesitate, he leaps onto a floating platform just as a wall of white roars up behind him, burying the path in silence.

Reader's Guide

The highest mountain on Earth is Mount Everest in the Himalayas of Asia, whose summit is 8850 m above mean sea level. The highest known mountain on any planet in the Solar System is Olympus Mons on Mars at 21171 m. The highest mountain on Earth from base to peak is Mauna Kea in Hawaii, which rises 9,330 m from its base at the bottom of the ocean; some scientists consider it to be the tallest on Earth. There is no universally accepted definition of a mountain. Elevation, volume, relief, steepness, spacing and continuity have been used as criteria for defining a mountain. In the Oxford English Dictionary a mountain is defined as 'a natural elevation of the earth surface rising more or less abruptly from the surrounding level and attaining an altitude which, relatively to the adjacent elevation, is impressive or notable.' Whether a landform is called a mountain may depend on local usage. John Whittow's Dictionary of Physical Geography states 'Some authorities regard eminences above 600 m as mountains, those below being referred to as hills.' Conversely, some lower mountain ranges with an average elevation between 1500 m and 2000 m may instead be called hills, such as the Sivalik Hills in the Himalayas and the Black Hills in the United States. In the United Kingdom and the Republic of Ireland, a mountain is usually defined as any summit at least 2000 ft high, which accords with the official UK government's definition that a mountain, for the purposes of access, is a summit of 2000 ft or higher. In addition, some definitions also include a topographical prominence requirement, such as that the mountain rises 300 m above the surrounding terrain. At one time, the United States Board on Geographic Names defined a mountain as being 1000 ft or taller, but has abandoned the definition since the 1970s. Any similar landform lower than this height was considered a hill. However, today, the United States Geological Survey concludes that these terms do not have technical definitions in the US. The UN Environmental Programme's definition of 'mountainous environment' includes any of the following: Class 1: Elevation greater than 4500 m. Class 2: Elevation between 3500 and 4500 m. Class 3: Elevation between 2500 and 3500 m. Class 4: Elevation between 1500 and 2500 m, with a slope greater than 2 degrees. Class 5: Elevation between 1000 and 1500 m, with a slope greater than 5 de

Did You Know?

• The highest mountain on Earth is Mount Everest in the Himalayas of Asia, whose summit is 8850 m above mean sea level.
• The highest known mountain on any planet in the Solar System is Olympus Mons on Mars at 21171 m.
• The highest mountain on Earth from base to peak is Mauna Kea in Hawaii, which rises 9,330 m from its base at the bottom of the ocean; some scientists consider it to be the tallest on Earth.