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Are Volcanoes Mountains?
Mountains are formed due to the movement and opposition of tectonic plates. They form along the edges of continents where the pressure exerted by one plate over another causes a rise in elevation. This is called orogeny.
Volcanoes are formed when molten rock rises up towards the surface of the Earth. When it reaches the crust, it erupts and creates lava fields, cinder cones, calderas, pyroclastic flows, etc.
There are many similarities between mountains and volcanoes; however, there is a big difference in their formation. A mountain results from various geologic processes, including movement and opposition of tective plates.
On the other hand, volcanoes form around vents when magma flows out towards the earth’s surface and reaches the surface.
Formation of a Mountain
The Earth’s outermost shell is called the lithosphere. This thin layer of rock covers most of our planet. Beneath it lies the asthenosphere, a hot, plastic material. The upper part of the asthenosphere is divided into five major tectonic plates. These plates constantly move relative to one another, sometimes slowly, sometimes quickly.
When two plates meet, there is friction and heat. Friction causes the rocks to melt and flow together, creating mountains. As the plates continue to rub against one another, the molten rock cools and hardens, creating deep trenches where plate boundaries converge.
In the case of North America, three plates—the North American Plate, the Caribbean Plate, and the South American Plate—are colliding. They are pushing up the Appalachian Mountains while sinking beneath the Gulf of Mexico.
Formation of a Volcano
Volcanic activity occurs when molten rock rises from deep within Earth’s crust. This process creates a volcano. Volcanoes range in size from small cinder cones to massive supervolcanoes. Some volcanoes form during periods of intense seismic activity, while others develop slowly over millions of years.
A volcano results from collecting erupted material after several volcanic eruptions, such as pyroclastic flows, lahars, and ash clouds. These materials accumulate into a pile of loose material called tephra. Tephra builds up around the volcano’s base and becomes hardened into rock.
As the volcano grows taller, it pushes the surrounding area away from the center of the volcano. Eventually, the volcano reaches the earth’s surface, where it erupts explosively. Explosive eruptions eject large amounts of hot gas and liquid rock from the volcano. They often produce pyroclastic flows and lahars.
Hot magma flows through a volcanic vent and cools upon hitting the ground. When magma hits the water, steam is produced. In some cases, the heat causes the water to freeze. This produces ice sheets that build up and eventually push out the volcano’s sides. The resulting mound of cooled magma is called a caldera.
Volcanic Facts
There are many types of volcanic eruptions, depending on the type of magma involved. A typical volcanic eruption begins with the formation of a volcanic vent. Volcanic vents are openings into the Earth where magma rises to the surface.
Once formed, the vent becomes a conduit for molten material called magma. When magma reaches the Earth’s surface, it forms a cone shape. If there is no outlet for the magma, it builds pressure inside the cone and eventually breaks free, causing an explosion. Such explosions are called effusive eruptions.
Effusive eruptions
Often occur at mid-ocean ridges, along plate boundaries, and beneath large bodies of water such as lakes and oceans. These eruptions form cones because the rising column of gas and ash cools rapidly and hardens. As the hardened magma moves away, it leaves behind a crater.
Convective eruptions
Occur when magma enters the ground near the surface of the Earth. Convection involves heat transfer due to the movement of fluids. In convective eruptions, the magma heats up and expands. Eventually, the expanding magma reaches the surface and explodes. Because the magma is moving quickly, the resulting blast wave can travel hundreds of miles.
A subduction zone is a region where one tectonic plate dives under another. At the boundary between the plates, there is friction and heating. Hot rocks melt and rise to the surface, forming a chain of volcanoes. Subduction zones are found around the Pacific Ocean and the Indian Ocean. They are responsible for most volcanic activity in Indonesia, Japan, and Chile.
Plate Tectonics
The Earth is divided into several rigid plates that move over each other like pieces of a puzzle. Each piece of the puzzle is called a plate. Plates float on a layer of hot, viscous fluid called the mantle. Some plates are composed mainly of silicate minerals, while others are rich in iron. There are seven major plates:
- The lithosphere is the outermost part of the Earth, consisting mostly of crust. It includes all the continents, ocean floors, and islands.
- The asthenosphere is the lower portion of the mantle. It consists mostly of basalt (an igneous rock) and peridotite (a metamorphic rock).
- The upper mantle is located below the asthenosphere. It consists mostly of olivine (a mineral), garnet (another mineral), pyroxene (yet another mineral), and plagioclase (a glassy mineral).
- The core is made up of solid metal and liquid iron. It lies deep within the Earth and is surrounded by the mantle.
- The mantle is the middle layer of the Earth. It is mostly comprised of peridotite and contains a small amount of granite.
- The crust is the top layer of the Earth. Its composition varies from place to place. Most of the continental crust is made up of granitic rocks.
- The atmosphere is the thin shell surrounding the entire planet. It consists mostly of nitrogen and oxygen gases.
There are two ways to divide the Earth’s plates: according to their location or according to how they move relative to each other. The first way divides the plates based on their position in space. The second way divides them based on their motion through time.
Location-Based Divisions
There are three main locations where plates meet:
- Convergent Boundaries – Two adjacent plates converge toward each other and slide past each other. This causes a new ocean floor to be created.
- Divergent Boundary – Two adjacent plates diverge away from each other. New landmasses form as the plates spread apart.
- Transform Fault – A plate slides beneath another plate at an angle. This creates a fold in the Earth’s crust.
Movement-Based Divisions
In addition to these three types of boundaries, there are also four different modes of plate movement:
- Plate Tectonic Drift – One plate
Additional Differences Between a Mountain and a Volcano
A volcano is a geologic feature characterized by fissures and vents through which molten rock flows out. Volcanic eruptions occur when underground heat causes rocks to melt and form lava.
This creates explosive gases and ash clouds that rise into the atmosphere. When these gases cool down, they turn into volcanic bombs called tephra.
These bombs fall back to earth, where they become part of a layer known as a pyroclastic flow. Some types of volcanoes produce lava flows, while others produce cinder cones, shield volcanoes, or stratovolcanoes.
Mountain ranges often consist of several different types of mountains. For example, many types of mountains include peaks, ridges, domes, plateaus, valleys, and basins. Each type of mountain has unique characteristics and features.
Different Types of Mountains
Mountains are very important natural features of Earth. They are considered as one of the four major divisions of the planet’s surface. These large masses of rock are formed due to the accumulation of sediments over millions of years. As a result, mountains are found throughout the world.
Some of the famous mountains of the world include
- Mount Everest
- Mount McKinley
- Mount Fuji
- Mount Kilimanjaro
- Mount Elbrus
- Mount Aconcagua
- Mount Kosciuszko
The term ‘mountain’ describes a mass of rock rising above the surrounding landscape. Many types of mountains depend upon the geological processes that caused their formation.
Fold mountains
These are the tallest among all other types of mountains. They are formed due to the folding of rocks over long periods. Fold mountains are usually located near tectonic plate boundaries where continental plates collide. In addition, fold mountains are often associated with volcanic activity.
Fault block mountains
These are other types of mountains. They are formed due to the movement of faults across sedimentary deposits. Faults are cracks within the earth’s crust. When two blocks of rock move away from each other, it creates a fault. Fault mountains are usually located in rift zones where two tectonic plates meet.
Volcanic mountains
These are formed due to the eruption of volcanoes. They are usually located close to active volcanoes.
Plateau mountains
These are formed due to erosion. Erosion is the process of wearing down the surfaces of rocks. Plateaus are flat areas worn out by the wind, water, and ice.
Dome mountains
Are upwarps of mountains. Upwarps are uplifted regions of the earth’s surface. They are formed due to tectonic forces. Dome mountains are much smaller than the other types of mountains. However, they are easier to identify because they have a distinct shapes.
Ridge mountains
These are also referred to as escarpments. Escarpments are steep-sided hills. Ridge mountains are formed due to tectonic movements. The most common ridge mountains are found along the edges of continents.
Peak mountains
These are the highest points on a continent. Peak mountains are formed due to uplift. Uplift is the process of lifting the land upward. It occurs when the weight of the material above the area becomes too great for the underlying rock to support. This causes the top rock layers to break off and rise into the air.
Basin mountains
These are the lowest point on a continent. Basin mountains are formed due to subsidence. Subsidence is the process of sinking or dropping the land downward. It happens when the weight of the materials below the area becomes too heavy for the underlying rock to hold. This causes the bottom layer of rock to sink or drop into the lower levels of the earth.
