Layers of the Earth

Front

Crust Noun

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[kruhst]

Back

Crust

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The outermost solid layer of Earth, composed of oceanic and continental types, representing less than 1% of the planet's mass.

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Example: This diagram shows a cross-section of the Earth, identifying the Crust as the planet's thinnest, outermost solid layer, located above the mantle.

Front

Mantle Noun

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[man-tl]

Back

Mantle

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The layer of hot, ultramafic rock between Earth's crust and core, making up about 68% of Earth's mass.

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Example: This diagram shows a cutaway of the Earth, clearly labeling the Mantle as the thick layer located between the thin outer Crust and the Core.

Front

Core Noun

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[kor]

Back

Core

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The central part of the Earth, composed mainly of iron metal, which constitutes about 31% of the Earth's mass.

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Example: This diagram shows a cross-section of the Earth, identifying the core (split into inner and outer layers) as the planet's hot, dense center.

Front

Lithosphere Noun

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[lith-uh-sfeer]

Back

Lithosphere

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The rigid outer part of the Earth, consisting of the crust and the brittle portion of the upper mantle.

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Example: This diagram shows a cross-section of the Earth, highlighting that the lithosphere is the rigid outer layer composed of the crust and the solid uppermost mantle.

Front

Asthenosphere Noun

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[as-then-uh-sfeer]

Back

Asthenosphere

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The partially molten layer of the upper mantle below the lithosphere, which behaves plastically and is able to flow.

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Example: This diagram shows the asthenosphere as the 'plastic' layer of the upper mantle, located directly beneath the rigid lithosphere.

Front

Atmosphere Noun

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[at-muh-sfeer]

Back

Atmosphere

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The thin layer of gases, primarily nitrogen and oxygen, that envelops the Earth and is held by gravity.

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Example: This diagram shows the atmosphere is divided into five main layers, each with unique altitudes, temperatures, and phenomena like weather, meteors, or auroras.

Front

Hydrosphere Noun

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[hahy-druh-sfeer]

Back

Hydrosphere

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The total amount of water on a planet, including all water on the surface, underground, and in the air.

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Example: This diagram shows the hydrosphere as all the water on Earth's surface, including the lake shown, in relation to the land (lithosphere), air (atmosphere), and life (biosphere).

Front

Biosphere Noun

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[bahy-oh-sfeer]

Back

Biosphere

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The global ecological system that integrates all living beings and their relationships with the non-living elements of Earth.

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Example: The biosphere is the zone of life on Earth, encompassing all living things in the air (atmosphere), on land (lithosphere), and in water (hydrosphere).

Front

Ultramafic Adjective

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[uhl-truh-maf-ik]

Back

Ultramafic

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A type of igneous rock with very low silica content, rich in minerals such as magnesium and iron.

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Example: This image shows that ultramafic rocks, like the peridotite found in the Earth's mantle, are made of minerals such as green olivine and dark pyroxene.

Front

Brittle Adjective

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[brit-l]

Back

Brittle

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A property of a material that breaks or shatters when subjected to stress without significant deformation, characteristic of the lithosphere.

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Example: This diagram shows a brittle fracture, where a material snaps cleanly without bending, which is how the Earth's rigid lithosphere breaks to create faults.