A plateau is a distinctive elevated landform, often recognized as a high plain or tableland. These expansive geological features are characterized by their relatively flat top surfaces, which rise noticeably above the surrounding terrain. Found on every continent, plateaus are shaped by dynamic geological processes and influence diverse landscapes.
Defining a Plateau
A plateau is an extensive area of flat upland, distinctively elevated above its surroundings. Its defining characteristics include a broad, relatively flat or gently undulating top surface, often referred to as a tableland. This elevated terrain typically features steep slopes or escarpments on at least one side, creating a sharp boundary with lower lands. Plateaus vary considerably in size, ranging from isolated features to vast regions spanning thousands of kilometers.
Their elevation can differ significantly, from a few hundred meters to several thousand meters above sea level. Unlike mountains, which culminate in sharp peaks, plateaus are defined by their expansive, level summits. This combination of elevation and flat topography distinguishes plateaus from other landforms like plains, which are low-lying, or hills, which lack an extensive flat upper surface.
How Plateaus Form
Plateaus are shaped by various geological processes, primarily involving the uplift of the Earth’s crust and subsequent erosion. One significant mechanism is tectonic uplift, where the movement of Earth’s tectonic plates causes large blocks of the crust to rise. This can occur through crustal shortening, where one crustal block is thrust over another, or through thermal expansion from the mantle. Such forces slowly elevate vast areas, maintaining a relatively flat surface.
Volcanic activity also contributes significantly to plateau formation. Extensive lava flows, particularly fluid basaltic lavas, accumulate through numerous eruptions from fissures. These successive layers of hardened lava spread across the landscape, burying pre-existing terrain and building up a broad, flat elevated area. The resistance of these volcanic rocks to erosion helps preserve the plateau’s flat surface.
Erosion plays a dual role in shaping plateaus. Differential erosion by water and wind wears away softer surrounding rocks, leaving more resistant, elevated areas standing. Rivers can incise deep canyons into existing plateaus, dissecting them while the overall elevated flat top remains. Glacial action can also contribute, eroding mountain ranges and leaving behind elevated, flat-topped remnants.
Major Types of Plateaus
Plateaus are categorized based on their geological setting and interaction with surrounding features.
Intermontane Plateaus
These plateaus are situated between mountain ranges, often enclosed by fold mountains. They are among the world’s highest, formed by the collision of tectonic plates that uplift the land between mountain belts. The Tibetan Plateau, nestled between the Himalayas and Kunlun Mountains, exemplifies this type.
Continental Plateaus
Also known as shield plateaus, these are extensive, elevated flatlands forming a significant part of a continent’s interior. They are typically bordered by plains or oceans and can form through broad continental uplift or widespread lava sheets. The Antarctic Plateau is a notable example, covering a large portion of the continent.
Volcanic Plateaus
Formed directly by widespread volcanic eruptions, these plateaus result from successive lava flows accumulating to create an elevated, flat surface. They are characterized by solidified basaltic rock. The Columbia Plateau in the northwestern United States and the Deccan Plateau in India are prominent examples, often having fertile soils derived from volcanic ash and weathered basalt.
Dissected Plateaus
These are uplifted areas that have undergone significant erosion by rivers and streams, resulting in a rugged, highly incised landscape. While the overall elevation remains, the surface is cut by deep valleys and canyons, giving it a somewhat mountainous appearance. The Allegheny Plateau in the eastern United States is an example, where rivers have carved intricate patterns into the uplifted terrain.
Global Distribution and Notable Examples
Plateaus are distributed across all continents, forming significant geographical features worldwide. Many of the world’s most impressive plateaus are found in Asia, North America, Africa, and South America.
The Tibetan Plateau in Asia is the highest and largest globally, often called the “Roof of the World.”
In North America, the Colorado Plateau spans parts of Utah, Arizona, New Mexico, and Colorado, famously dissected by the Grand Canyon.
The Columbia Plateau, located in the northwestern United States, is another major example shaped by extensive volcanic activity.
Africa hosts the Ethiopian Highlands, the continent’s highest plateau.
South America is home to the Altiplano Plateau, situated within the Andes Mountains, making it the world’s second-highest.
The Deccan Plateau, forming a large part of southern India, is known for its extensive basaltic rock formations.
Ecological and Human Significance
Plateaus support unique ecological systems and have influenced human development. Their elevation creates distinct climatic conditions, often cooler and windier than surrounding lowlands, affecting vegetation types and growth patterns. High-altitude plateaus may host specialized alpine flora, while lower, more temperate plateaus can support diverse grasslands or forests. The relatively flat terrain can also lead to unique drainage patterns, sometimes forming internal basins that support specific wetland ecosystems or dry, arid environments.
For human populations, plateaus have historically offered defensible locations for settlements and provided varied resources. Many plateaus contain rich mineral deposits, including iron, coal, gold, and diamonds, making them economically valuable. Their flat surfaces, despite elevation, can be suitable for agriculture, with terraced farming techniques often employed on sloped edges. The specific soil composition, such as the basalt-derived black soils of the Deccan Plateau, can be particularly fertile. Plateaus also serve as important routes for trade and migration due to their relatively traversable flat tops compared to rugged mountain ranges.