Earth
Various sciences that study the Earth, either as a physical entity, or as a living environment for plants, animals and human beings.
GEOLOGY
Science whose subject is the history, structure and evolution of the terrestrial globe.
structure of the Earth
The Earth is formed of three concentric layers: the core, the mantle and the crust; these are separated by transition zones called discontinuities.
section of the Earth’s crust
The Earth’s crust, continental and oceanic, is composed mainly of sedimentary, metamorphic and igneous rock.
tectonic plates
Immense portions of the lithosphere that slide over the asthenosphere; this shifting movement shapes the Earth’s topography.
earthquake
Sudden tremor in a region of the Earth’s crust caused by one rock mass sliding against another.
![seismographs [1]](/images/earth/geology/earthquake/seismographs_1.png "seismographs [1] image")
![seismographs [2]](/images/earth/geology/earthquake/seismographs_2.png "seismographs [2] image")
volcano
Landform built up as lava and ash are ejected from the upper mantle during successive eruptions, accumulating and solidifying on the surface.
glacier
Mass of ice resulting from the accumulation and compression of snow; it moves under its own weight.
cave
Natural underground cavity that results from the slow dissolution and erosion of rock by water.
landslides
Ground movements that vary in speed, depending on the slope’s gradient, the nature of the soil and what triggers it.
watercourse
Natural flow of water that varies in size, depending on the ground slope and the number of tributaries.
ocean floor
Part of the Earth’s surface beneath the seas and the oceans; its topography is highly variable.
ocean trenches and ridges
Trench: very deep, elongated cavity bordering a continent or an island arc; it forms when one tectonic plate slides beneath another. Ridge: underwater mountain range that criss-crosses the oceans and is formed by rising magma in a zone where two plates are moving apart.
common coastal features
Area where the land meets the sea; its features vary depending on climate, wind, sea and the type of rocks of which it is composed.
