HKDSE Geography/M1/The Earth's Layers

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The various layers of Earth are summed up below:

Layer (by chemical composition) Layer (by state) Maximum depth
Crust (sial/sima) (1) Solid lithosphere (4) 30km
Mantle (Fe and Al) (2) 100km
Plastic asthenosphere (5) 640km
Solid lower mantle 2800km
Core (Fe and Ni) (3) Liquid outer core (6) 4600km
Solid inner core (7) 6370km

Crust[edit | edit source]

The crust is a solid layer on the earth's surface. It includes continental and oceanic crusts.

Continental Oceanic
Thickness Thicker Thinner
Density Lighter Denser and heavier
Composition Sial - silica and aluminium Sima - silica and magnesium
Geology Mainly granitic Mainly basaltic
Remarks Includes continents and continental shelves

Mantle[edit | edit source]

It is denser, made of aluminium and iron, and divided into three parts.

Upper mantle Lower mantle
Rigid mantle Asthenopshere
State Solid Liquid Solid
Made of Rocks Magma Rocks

Core[edit | edit source]

It is rich in iron and nickel. The outer core is a molten liquid. The inner core is a high-pressure solid.