Mountain

We explain what mountains are, how they are formed, and describe the plant and animal life they host. In addition, we explore their importance, and the world’s highest mountains.

What is a mountain?

A mountain is a natural elevation of Earth’s surface. It is characterized by having significantly higher altitudes than the surrounding areas, as well as steep slopes.

Some mountains appear as isolated elevations, standing out for their great height in relation to the lower-elevation surrounding land. Others are part of extensive mountain belts known ranges, which can consist of hundreds of mountains and stretch for thousands of miles.

Earth’s mountains were formed by tectonic motion over geologic time. The collision and thrust of two tectonic plates cause the Earth’s crust to deform, and mountains to uplift.

Tectonic forces cause magma to rise from the interior of the planet and erupt onto the surface. For this reason, a large number of mountain ranges are made up of volcanoes, which are a specific type of mountainous landform.

Mountains play a vital role in the water cycle: snow and ice accumulate at high altitudes, melting during the warmer months to form most rivers on the planet.

• See also: Plateau

How are mountains formed?

The process of mountain formation is called orogenesis. Orogenesis occurs due to the collision and thrust of two ocean plates, an oceanic plate and a continental one, or two continental plates.

• When two oceanic plates collide, elevations form in the oceanic crust. If these rise above the surface of the water, arcs and ocean volcanoes are formed. An example of this is the Aleutian Islands near Alaska.
• When an oceanic plate and a continental plate collide, mountain ranges form along continental margins. The plates' thrust causes one plate to subduct beneath the other (a process called subduction) and the upper plate to fold, creating mountains and volcanoes. An example of this is the Andes mountain range.
• When two continental plates collide and thrust each other, high and extensive mountain ranges are formed. Since neither plate can subduct due to their similar weight and density, the collision is greater than in the other cases, resulting in much more significant orogenesis. An example is the Himalayas.

Structure of a mountain

The structure of mountains is as follows:

• Base or foot. It is the lowest part of all the mountain formation.
• Summit, peak, or crest. It is the uppermost portion of a mountain, being its most prominent feature, and determining its altitude in feet or meters above sea level.
• Slope or side. They are the inclined sides of a mountain connecting the base to the summit. They may have varying degrees of steepness.

One way to determine whether a mountain is young or old is its shape. Young mountains have sharp peaks and steep slopes. In contrast, old mountains feature rounded summits and gentler slopes, shaped by millions of years of erosion.

Climate of mountains

Mountain climates are primarily shaped by altitude. As elevation increases, temperature drops, making high-altitude mountain regions the coldest. Therefore, high mountain summits are always covered in ice, since the cold persists all year round, causing water and moisture to freeze.

At lower altitudes, atmospheric heat is greater, resulting in higher temperatures. This explains why the base of a mountain is always warmer than its summit.

Flora and fauna of mountains

While plant life in mountains varies with climate and geographical location, it usually experiences a gradual and steady change as elevation increases.

Near the base, vegetation is usually more abundant and diverse, due to higher temperatures than in the summit. As elevation increases, cold-resistant plant species predominate, vegetation decreases in size, trees disappear, and only grasses and shrubs can be found. When elevation is too high and the cold becomes extreme, vegetation disappears altogether.

Wildlife in mountains also depends on altitude. Most animal life is concentrated in lower and mid-altitudes, where vegetation provides shelter and sustenance, and there is more oxygen.

In regions with thicker vegetation, large predators such as pumas, bears, and wolves can be found. In warmer mountainous areas, primates and jungle-dwelling felines may also appear.

As altitude increases, harsh climatic conditions do not support animal life. At extreme altitudes, fauna is virtually nonexistent, with the exception of a few insects and birds.

Importance of mountains

Mountains play a key role in the planet’s climate and hydrologic dynamics. In addition, they can mitigate the intensity of natural disasters.

• Climate dynamics. Mountains influence atmospheric patterns by acting as physical barriers that alter air circulation and rainfall distribution across the planet. They also affect temperature, causing atmospheric heat to be lower at higher altitudes.
• Hydrologic dynamics. Mountains are a vital source of freshwater. Melting snow and ice from mountains feed rivers and streams, providing vital water supplies for billions of people worldwide. The melting of snow and glaciers in mountains serve as a crucial reservoir of freshwater for the hydrologic cycle and as a water supply for the future.
• Natural disasters. Mountains act as buffers for certain natural disasters by reducing the speed and intensity of extreme weather events such as tropical storms and hurricanes. However, mountainous regions are also prone to natural disasters like earthquakes and volcanic eruptions, which can cause significant damage to nearby populations.

Highest mountains in the world

The highest mountains in the world are:

• Mount Everest. Standing at 29,031 feet (8,846 m), it is the highest mountain on Earth. It is located on the border between Nepal and China in the Himalayas.
• K2. Reaching 28,251 feet (8,611 m), it is situated on the border between Pakistan and China.
• Kangchenjunga. With a height of 28,169 feet (8,586 meters), it lies between India and Nepal.
• Lhotse. At 27,940 feet (8,516 meters) it is located in Tibet, on the border between China and Nepal.
• Makalu. At 27,766 feet (8,463 m), it is situated in Tibet, on the border between China and Nepal.

The highest mountain in the Americas is Aconcagua, standing at 22,838 feet (6,961 m) in the Andes. It is also home to the Ojos del Salado, the highest volcano on the planet, at 22,608 feet (6,891 m).

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