• plateau
    This cowboy gazes out from a small plateau in Monument Valley, Arizona, across an enormous plateau—the Colorado Plateau, which covers most of the American Southwest.

    Photograph by Brendan Schoon, My Shot

    Oceanic Plateaus
    Plateaus in the ocean are divided into two groups. One group is made of continental crust. The other is made of igneous rock. Igneous oceanic plateaus represent an age between the older, less-dense continental crust and the younger, more dense oceanic crust.

    A plateau is a flat, elevated landform that rises sharply above the surrounding area on at least one side. Plateaus occur on every continent and take up a third of the Earths land. They are one of the four major landforms, along with mountains, plains, and hills.

    There are two kinds of plateaus: dissected plateaus and volcanic plateaus. A dissected plateau forms as a result of upward movement in the Earths crust. The uplift is caused by the slow collision of tectonic plates. The Colorado Plateau, in the western United States, has been rising about .03 centimeter (.01 inch) a year for more than 10 million years.

    A volcanic plateau is formed by numerous small volcanic eruptions that slowly build up over time, forming a plateau from the resulting lava flows. The North Island Volcanic Plateau covers most of the central part of the North Island of New Zealand. This volcanic plateau still has three active volcanoes: Mount Tongariro, Mount Ngauruhoe, and Mount Ruapehu.

    Erosion can influence the shape of a plateau. Soft rock often erodes away on the top of a plateau. Many plateaus are therefore topped with a hard, durable surface called caprock. Caprock protects the plateau from erosion of the soil underneath it.

    Valleys form when river water cuts through the plateau. The Columbia Plateau, between the Cascade and Rocky mountains in the northwestern United States, is cut through by the Columbia River.

    Erosion shapes plateaus in other ways. Sometimes, a plateau is so eroded that it is broken up into smaller raised sections called outliers. Many outlier plateaus are composed of very old, dense rock formations. Iron ore and coal often are found in plateau outliers.

    The largest plateau in the world is the Tibetan Plateau, located in central Asia. It stretches through the countries of Tibet, China, and India and occupies an area of 2.5 million square kilometers (1.5 million square miles), which is four times the size of the U.S. state of Texas.

  • Term Part of Speech Definition Encyclopedic Entry
    active volcano Noun

    volcano that has had a recorded eruption since the last glacial period, about 10,000 years ago.

    caprock Noun

    strong, hard rock that remains on top of a mesa.

    coal Noun

    dark, solid fossil fuel mined from the earth.

    continent Noun

    one of the seven main land masses on Earth.

    Encyclopedic Entry: continent
    continental crust Noun

    thick layer of Earth that sits beneath continents.

    dense Adjective

    having parts or molecules that are packed closely together.

    dissected plateau Noun

    flat, elevated landform created by upward movement of the Earth's crust.

    durable Adjective

    strong and long-lasting.

    erosion Noun

    act in which earth is worn away, often by water, wind, or ice.

    Encyclopedic Entry: erosion
    igneous rock Noun

    rock formed by the cooling of magma or lava.

    iron Noun

    chemical element with the symbol Fe.

    landform Noun

    specific natural feature on the Earth's surface.

    Encyclopedic Entry: landform
    oceanic crust Noun

    thin layer of the Earth that sits beneath ocean basins.

    oceanic plateau Noun

    flat, elevated landform rising from the ocean floor.

    ore Noun

    deposit in the Earth of minerals containing valuable metal.

    Encyclopedic Entry: ore
    outlier Noun

    part of a landform separated from the rest by erosion.

    plateau Noun

    large region that is higher than the surrounding area and relatively flat.

    Encyclopedic Entry: plateau
    river Noun

    large stream of flowing fresh water.

    Encyclopedic Entry: river
    soft rock Noun

    solid mineral matter that is easily worn or broken.

    tectonic plate Noun

    large, moveable segment of the Earth's crust.

    Tibetan Plateau Noun

    flat, elevated landform located in Tibet, China, and India. Also known as the "rooftop of the world."

    valley Noun

    depression in the Earth between hills.

    volcanic plateau Noun

    flat, elevated landform created by layers of lava from volcanic eruptions.

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