Earth's Layers and Plate Tectonics

Vocabulary terms covering the four layers of the Earth, types of tectonic plates, and the major types of plate boundaries.

Inner core

The solid, innermost layer of the Earth made of iron and nickel, with temperatures as hot as the surface of the sun.

Outer core

A layer made of iron and nickel in liquid form that is extremely hot.

Mantle

The layer of the Earth made up of magma or molten rock located below the crust.

Crust

The thin, outermost layer of solid rock that is split into many different pieces called tectonic plates.

Tectonic plates

Large pieces of the Earth's crust that can be oceanic or continental and are moved by energy from the mantle.

Oceanic plates

Tectonic plates that are found mainly under the ocean.

Continental plates

Tectonic plates that are mainly found under land.

Destructive or convergent plate boundary

A boundary where plates are pushed together, often leading to the creation of mountains, earthquakes, and tall, steep volcanoes.

Nazca plate

An oceanic plate that collides with the South American plate, forcing it underneath and creating the Andes Mountains.

Constructive or divergent plate boundary

A boundary, usually found under oceans, where plates move apart and magma rises to form shallow sided volcanoes.

Mid-Atlantic Ridge

An example of a divergent plate boundary on the floor of the Atlantic Ocean where the Eurasian and North American plates are moving apart.

Transform faults

Tectonic boundaries where plates move past each other, causing pressure to build and release suddenly as earthquakes.

San Andreas Fault

A famous transform fault in the USA that forms the boundary between the Pacific Plate and the North American Plate.