• Tectonic plates, the massive slabs of Earth’s lithosphere that help define our continents and ocean, are constantly on the move. Plate tectonics is driven by a variety of forces: dynamic movement in the mantle, dense oceanic crust interacting with the ductile asthenosphere, even the rotation of the planet.
    Geologists studying the Earth use scientific observation and evidence to construct a picture of what the Earth looked like at different periods in the geologic past. Use this map gallery to better understand how plate tectonics created the ocean and continents we are familiar with today.
  • Term Part of Speech Definition Encyclopedic Entry
    asthenosphere Noun

    layer in Earth's mantle between the lithosphere (above) and the upper mantle (below).

    continent Noun

    one of the seven main land masses on Earth.

    Encyclopedic Entry: continent
    dense Adjective

    having parts or molecules that are packed closely together.

    ductile Adjective capable of withstanding a certain amount of force by changing form before fracturing or breaking.
    geologic Adjective

    having to do with the physical formations of the Earth.

    geologist Noun

    person who studies the physical formations of the Earth.

    lithosphere Noun

    outer, solid portion of the Earth. Also called the geosphere.

    Encyclopedic Entry: lithosphere
    mantle Noun

    middle layer of the Earth, made of mostly solid rock.

    Encyclopedic Entry: mantle
    massive Adjective

    very large or heavy.

    oceanic crust Noun

    thin layer of the Earth that sits beneath ocean basins.

    plate tectonics Noun

    movement and interaction of the Earth's plates.

    rotation Noun

    object's complete turn around its own axis.

    Encyclopedic Entry: rotation
    tectonic plate Noun

    massive slab of solid rock made up of Earth's lithosphere (crust and upper mantle). Also called lithospheric plate.