Plateaus are expansive, elevated landforms that stand distinctly above their surrounding terrain. These vast geological features cover approximately one-third of Earth’s land surface and are found on every continent. They represent significant elements of our planet’s diverse landscapes.
What Defines a Plateau?
A plateau, also known as a high plain or tableland, is characterized by its significant elevation and a relatively flat or gently undulating top surface. This elevated area typically rises sharply from the adjacent land, often marked by steep slopes or escarpments on at least one side. While the top surface appears flat, many plateaus feature rugged terrain with deep valleys and canyons carved by erosion.
Elevation of plateaus can vary, ranging from a few hundred feet to thousands of meters above sea level. For instance, the Tibetan Plateau averages over 4,500 meters (14,800 feet) in elevation. Unlike mountains, which continuously elevate to a peak, plateaus maintain a broad, flat expanse at their summit. These features distinguish plateaus as unique landforms.
Why a Precise Count is Elusive
Determining an exact number of plateaus in the world is not possible due to several complexities. One primary reason is the lack of a single, standardized definition used across geological and geographical disciplines. Different experts may apply varying criteria for what constitutes a plateau, particularly regarding minimum elevation, area, or the degree of flatness required for its top surface.
Scale and size variations also contribute to the difficulty in counting. Plateaus range from vast continental-sized formations to smaller, more localized tablelands, making it challenging to draw clear boundaries. Geological processes are continuously shaping these landforms; erosion and tectonic activity mean plateaus are dynamic entities, with their boundaries and characteristics evolving over geological timescales. There is no central global authority that maintains a comprehensive and updated inventory of all plateaus.
Prominent Plateaus Across Continents
While a precise global count remains elusive, several prominent plateaus illustrate their diverse forms and widespread distribution. The Tibetan Plateau, often referred to as the “Roof of the World,” is the highest and largest plateau globally, spanning approximately 2.5 million square kilometers in Central Asia. It is bordered by mountain ranges, including the Himalayas, and is a source for major Asian rivers such as the Yangtze and Mekong.
In North America, the Colorado Plateau covers parts of Utah, Arizona, Colorado, and New Mexico, characterized by its high desert landscape and deeply carved canyons like the Grand Canyon. It features brightly colored, exposed sedimentary rock layers. The Deccan Plateau in southern India is another example, a large triangular landmass formed by extensive basaltic lava flows, giving it a distinctive step-like appearance. It covers an area of about 422,000 square kilometers and is bordered by the Western and Eastern Ghats mountain ranges.
The Ethiopian Highlands, sometimes called the “Roof of Africa,” represent a rugged mass of mountains and plateaus in Northeast Africa. This region is marked by escarpments and deep valleys, formed through volcanic activity and tectonic movements related to the Great Rift Valley. These examples highlight the varied geological origins and visual characteristics that define plateaus across the globe.
The Dynamic Nature of Plateau Formation
Plateaus form through several geological processes that elevate and shape Earth’s crust over long periods. One primary mechanism is tectonic uplift, where the movement and collision of continental plates cause large landmasses to rise. For instance, the height of the Tibetan Plateau is largely attributed to crustal shortening from the collision between the Indian and Eurasian tectonic plates.
Volcanic activity also plays a role in plateau creation. Volcanic plateaus, such as the Deccan Plateau, are formed by the accumulation of highly fluid basaltic lava that erupts from fissures and spreads over extensive areas. These successive lava flows build up thick layers that solidify to form elevated tablelands.
Erosion is another force that shapes plateaus. While not directly forming them, erosional processes, particularly by rivers and glaciers, can dissect existing high ground, carving deep valleys and canyons into the plateau surface. This ongoing erosion can leave behind isolated flat-topped remnants. These processes, often acting in combination, contribute to the diverse nature observed in plateaus worldwide.