The Mountains

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. The adjective montane is used to describe mountainous areas and things associated with them. The study of mountains is Orology.

There is no universally-accepted definition of mountain. In the United States, the following points of measurement have been used and taught in geography classes:

• Flat to 500 feet, base to highest point - Rolling Plain
• Highest point 501 to 999 feet above base - Hill
• Highest point 1000 feet or more above base - Mountain

Whether the landform is called a mountain may depend on usage among the local people. The highest point in San Francisco, California, is called Mount Davidson, notwithstanding its height of 990 feet, which makes it ten feet short of the minimum for a mountain in American appellation.
Other definitions of "mountain" include:

• Height over base of at least 2,500m
• Height over base of 1500-2500m with a slope greater than 2 degrees
• Height over base of 1000-1500m with a slope greater than 5 degrees

Local (radius 7km) elevation greater than 300m, or 300-1000m if local (radius 7km) elevation is greater than 300m

By this definition, mountains cover 64% of Asia, 25% of Europe, 22% of South America, 17% of Australia, and 3% of Africa. As a whole, 24% of the Earth's land mass is mountainous and 10% of people live in mountainous regions. Most of the world's rivers are fed from mountain sources, and more than half of humanity depends on mountains for water.

The 50 tallest mountains in the world are in Asia.

Exogeology deals with planetary mountains, which in that branch of science are usually called montes (singular - mons). The highest known mountain in the Solar System is Olympus Mons on the planet Mars (elevation 21,171 m).