Earth surface

Crust

Thin outermost layer of Earth where life exists; makes up about 1% of Earth’s mass.

Oceanic Crust

Type of crust found beneath the oceans; mainly composed of basaltic rock.

Continental Crust

Type of crust that forms the continents; mainly composed of granitic rock.

Basaltic Rock

Dark, dense igneous rock that makes up most of the oceanic crust.

Granitic Rock

Light-colored, coarse-grained igneous rock that makes up most of the continental crust.

Mohorovičić Discontinuity (Moho)

Boundary between Earth’s crust and mantle.

Mantle

Layer of hot, solid material located between the crust and core.

Magma

Molten rock material found within the mantle.

Magnesium Oxide

Mineral component abundant in the mantle that distinguishes it from the crust.

Peridotite

Igneous rock believed to make up most of the upper mantle.

Bridgmanite

Dominant mineral found in the lower mantle.

Lithosphere

Earth’s rigid outer layer composed of the crust and the uppermost mantle.

Asthenosphere

Soft, semi-fluid layer of the mantle on which tectonic plates move.

Mesosphere

Solid lower mantle located below the asthenosphere.

Mantle Convection

Process where hot, less dense material rises and cooler, denser material sinks.

Core

Innermost layer of Earth composed mainly of iron and nickel.

Outer Core

Liquid layer of molten iron and nickel surrounding the inner core.

Inner Core

Solid sphere of iron and nickel at Earth’s center due to immense pressure.

Lehmann Discontinuity

Boundary between the outer core and inner core.

Earth’s Magnetic Field

Protective field generated by the movement of molten iron in the outer core.

Gutenberg Discontinuity

Boundary between the mantle and the outer core.

Tectonic Plates

Large pieces of Earth’s lithosphere that move over the asthenosphere.

Silica

Major component found in Earth’s crust.

Iron

Main element composing Earth’s core.

Nickel

Dense metallic element found with iron in Earth’s core.