How Do Plateaus Form?

By John Misachi on August 6 2019 in Environment

The Tibetan plateau, the largest plateau in the world.
The Tibetan plateau, the largest plateau in the world.

Plateaus are geographical and geological landforms that occur on every continent and take up about one-third of the Earth's land. They can be defined as flat but fairly elevated landforms that rise above the surrounding areas on at least one side. A plateau is one of the four major landforms alongside plains, mountains, and hills. There are two types of plateaus depending on their mode of formation; the volcanic plateaus formed through volcanic eruption and the dissecting plateaus formed by the uplifting in the Earth’s crust. The world’s largest plateau is the Tibetan Plateau in central Asia which stretches through India and China and covers an area of approximately 1.5 million square miles.

Formation Process

Different processes are involved in the formation of plateaus and each process of the land formation is not an instant geological act as it takes millions of years for the raises, flat highlands to be built. Plateaus can be formed by one or more processes, including erosion, upwelling of magma, and extrusion of lava. They can either be created when magma is pushed upwards but does not break through the earth’s surface but rather raises a section of the crust. The lava can also break through the earth’s crust and build over a long time to form a raised land area. Below is a detailed description of how the various plateaus are formed.

Volcanic Plateaus

As the name suggests, a volcanic plateau is a type of plateau that is formed through volcanic activities such as the extrusion of lava or upwelling of magma. There are two different but closely related types of volcanic plateaus, namely lava plateau and pyroclastic plateau. The two are similar in their formation except that the lava plateau is characterized by lava flow while the pyroclastic plateau is characterized by a pyroclastic flow. Most plateaus are formed when the magma deep inside the Earth pushes upwards towards the surface but does not manage to break the crust and instead lifts the impenetrable rock above it. In this way, the flat area is uplifted to form a plateau. The repeated lava flow may also spill through the cracks on the ground and spread over an extensive surface. The eruption is always not violent because of the low viscosity of the lava. The extensive and successive flow of lava flow eventually covers the original surface and forms a massive lava plateau.

Sometimes, the volcanic eruption may be characterized by pyroclastic flows (volcanic matter and hot gases flowing away from an erupting volcano). These volcanic matters including volcanic ashes, pyroclastic rocks, tephra, and agglomerates are cemented into felsic, tuffs, and mafic to form a pyroclastic plateau. Some of the examples of volcanic plateaus include North Island Volcanic Plateau, Columbia Plateau, and Shirasu-Daichi.

Dissecting Plateaus

Some plateaus are formed over time through the action of rain and water on an uplifted region. The erosional process of the two agents on the uplifted region such as the mountain range leads to the formation of a geographical feature that is distinct from the surrounding area. Dissecting plateaus are severely eroded plateaus. Water is the major erosive force on plateaus. As it flows in the form of a river, it carves valley into the rocks and washes sediments into the sea. Over time, the valleys become giant land formations like the Grand Canyon of the Colorado Plateau. Wind and rain may eventually wear down a plateau, leading to the formation of buttes and mesas. Examples of dissecting plateaus include the Cumberland Plateau, Allegheny Plateau, Deccan Plateau, and the Blue Mountains.

Classification Of Plateaus

Although there are two broad types of plateaus depending on their formation, these landforms can also be classified based on their surrounding environment. The highest plateaus in the world, bordering the mountains are referred to as intermontane plateaus. Example include the Tibetan Plateau in Asia which is also the largest plateau in the world. Plateaus bordered by a plain or sea on one side and a mountain on the other side are known as piedmont plateaus. A classic example is the Piedmont Plateau located between the Atlantic Coastal Plain and the Appalachian Mountains. Continental plateaus are plateaus that are formed away from the mountains and are bordered on all sides by either oceans or plains. An example includes the Antarctic Plateau.

About The Tibetan Plateau

The Tibetan Plateau is the world’s largest and highest plateau. It is located in East and Central Asia and covers most parts of Qinghai and the Tibetan Autonomous Region in China and Himachal Pradesh and Ladakh in India. The plateau stretches about 620 miles north to south and 1,600 miles east to west. It has an elevation of over 14,800 feet and often referred to as the “Roof of the World.” The Tibetan Plateau covers an area of approximately 970,000 square miles. The formation of the plateau resulted from the continental collision along the convergent boundary between Eurasia Plate and Indo-Australian Plate over 5 million years ago. Interestingly, the Tibetan Plateau is still rising at an annual rate of 0.2 inches.

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