A volcanic plateau is a

plateau In geology and physical geography, a plateau (; ; : plateaus or plateaux), also called a high plain or a tableland, is an area of a highland consisting of flat terrain that is raised sharply above the surrounding area on at least one side. ...

produced by

volcanic activity Volcanism, vulcanism, volcanicity, or volcanic activity is the phenomenon where solids, liquids, gases, and their mixtures erupt to the surface of a solid-surface astronomical body such as a planet or a moon. It is caused by the presence of a he ...

. There are two main types: lava plateaus and pyroclastic plateaus.

Lava plateau

Lava plateaus are formed by highly fluid

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

ic lava during numerous successive eruptions through numerous vents without violent explosions (quiet eruptions). These eruptions are quiet because of the low viscosity of the lava and the small amount of trapped gases. The resulting sheet lava flows may be extruded from linear fissures or

rift In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben ...

s or gigantic volcanic eruptions through multiple vents characteristic of the prehistoric era which produced giant

flood basalt A flood basalt (or plateau basalt) is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava. Many flood basalts have been attributed to the onset of a hotspot (geolo ...

s. Multiple successive and extensive

lava Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...

flows cover the original landscape to eventually form a plateau, which may contain

lava field A lava field, sometimes called a lava bed, is a large, mostly flat area of lava flows. Such features are generally composed of highly fluid basalt lava, and can extend for tens or hundreds of kilometers across the underlying terrain. Morp ...

cinder cone A cinder cone or scoria cone is a steep, volcanic cone, conical landform of loose pyroclastic rock, pyroclastic fragments, such as volcanic ash, clinkers, or scoria that has been built around a volcanic vent. The pyroclastic fragments are forme ...

s, shield volcanoes and other

volcanic landforms A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often fo ...

. In some cases, a lava plateau may be part of a single volcano. An example is the massive Level Mountain

shield volcano A shield volcano is a type of volcano named for its low profile, resembling a shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more viscous lava ...

in northern

British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

, which covers an area of and a volume of . Perhaps the most extensive of all the subaerial basaltic plateaus existed during the

Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...

and possibly extended over of the northern

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

region. This region, known as the

Thulean Plateau The North Atlantic Igneous Province (NAIP) is a large igneous province in the North Atlantic, centered on Iceland. In the Paleogene, the province formed the Thulean Plateau, a large basaltic lava plain, which extended over at least in area and i ...

, is generally believed to have been broken up by the foundering of the Earth's crust to form the present

ocean basin In hydrology, an oceanic basin (or ocean basin) is anywhere on Earth that is covered by seawater. Geologically, most of the ocean basins are large  geologic basins that are below sea level. Most commonly the ocean is divided int ...

. Earth features numerous subaerial and

submarine A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or infor ...

volcanic plateaus, such as the

Columbia River Plateau The Columbia Plateau is an important geologic and geographic region that lies across parts of the U.S. states of Washington, Oregon, and Idaho. It is a wide flood basalt plateau between the Cascade Range and the Rocky Mountains, cut through by ...

(subaerial) and the vast

Ontong Java Plateau The Ontong Java Plateau (OJP) is a massive oceanic plateau located in the southwestern Pacific Ocean, north of the Solomon Islands. The OJP was formed around (Ma), with a much smaller volcanic event around 90 Ma. Two other southwestern Pacific pl ...

(submarine).

Pyroclastic plateau

Pyroclastic plateaus are produced by massive

pyroclastic flow A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of b ...

s. They are underlain by

pyroclastic rock Pyroclastic rocks are clastic rocks composed of rock fragments produced and ejected by explosive volcanic eruptions. The individual rock fragments are known as pyroclasts. Pyroclastic rocks are a type of volcaniclastic deposit, which are deposit ...

agglomerate Agglomerate (from the Latin ''agglomerare'' meaning "to form into a ball") is a coarse accumulation of large blocks of volcanic material that contains at least 75% bombs. Volcanic bombs differ from volcanic blocks in that their shape records flui ...

tephra Tephra is fragmental material produced by a Volcano, volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, ...

volcanic ash Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, produced during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to r ...

es cemented into

tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock co ...

mafic A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include ...

felsic In geology, felsic is a grammatical modifier, modifier describing igneous rocks that are relatively rich in elements that form feldspar and quartz.Marshak, Stephen, 2009, ''Essentials of Geology,'' W. W. Norton & Company, 3rd ed. It is contrasted ...

. Pyroclastic plateaus are also called

ignimbrite Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surrou ...

plateaus. Examples include the Shirasu-Daichi, which makes up almost all of southern

Kyūshū is the third-largest island of Japan's four main islands and the most southerly of the four largest islands (i.e. excluding Okinawa and the other Ryukyu (''Nansei'') Islands). In the past, it has been known as , and . The historical regio ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

, and the

North Island Volcanic Plateau The North Island Volcanic Plateau (often called the Central Plateau and occasionally the Waimarino Plateau) is a volcanic plateau covering much of central North Island of New Zealand with volcanoes, lava plateaus, and crater lakes. It contains t ...

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

References

{{Earth's landforms Volcanic landforms

Lava plateau

Pyroclastic plateau

See also

References