Mountains are massive landforms rising high above the Earth’s surface, caused by one or more geological processes: plate tectonics, volcanic activity and/or erosion.
Generally they fall into one of five categories – fold, fault-block, dome, volcanic and plateau – although there can be some overlap.
Mountains comprise about 25 per cent of our land mass, with Asia having more than 60 per cent of them. They are home to 12 per cent of the Earth’s population, and they don’t just provide beauty and recreation; more than half of the people on Earth rely on the fresh water that flows from the mountains to feed streams and rivers. Mountains are also incredibly biodiverse, with unique layers of ecosystems depending on their elevation and climate.
One of the most amazing things about mountains is that although they look solid and immovable to us, they’re always changing. Mountains rising from activity associated with plate tectonics – fold and fault-block- form slowly over millions of years. The plates and rocks that initially interacted to form the mountains continue to move up to 2cm each year, meaning that the mountains grow. The Himalayas, for example, grow about 1cm per year.
The volcanic activity that builds mountains can wax and wane over time. Mount Fuji, the tallest mountain in Japan, has erupted 16 times since 781AD. Mount Pinatubo in the Philippines erupted in the early-Nineties without any prior recorded eruptions, producing the second largest volcanic eruption of the 20th Century.
Inactive volcanic mountains – and all other types of mountains, for that matter – are also subject to erosion, earthquakes and other activity that can dramatically alter their appearances as well as the landscape around us. There are even classifications for the different types of mountain peaks that have been affected by glacial periods in Earth’s history. The bare, near-vertical mountaintop of the Matterhorn in the Alps, for example, is known as a pyramidal peak, or horn.
What are, the different types of mountain?
Volcanic – These mountains are created by the buildup of lava, rock, ash and other volcanic matter during a magma eruption. Examples: Mount Fuji, Mount Kilimanjaro
Plateau – Plateau mountains are revealed through erosion of uplifted plateaus. This is known as dissection. Examples: Catskill Mountains, Blue Mountains
Fold – This most common type of mountain is formed when two tectonic plates smash into each other. The edges buckle and crumble, giving rise to long mountain chains. Examples: Mount Everest, Aconcagua
Fault-block – Fault-block mountains form when cracked layers of crust slide against each other along faults in the Earth’s crust. They can be lifted, with two steep sides; or lifted, with one gently sloping side and one steep side. Examples: Sierra Nevada, Urals
Dome – These types of mountain also form from magma. Unlike with volcanoes, however, there is no eruption; the magma simply pushes up sedimentary layers of the Earth’s crust and forms a round dome-shaped mountain. Examples: Navajo Mountain, Ozark Dom.