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Crust

Crust

Earth's outer skin, layer of solid rock that includes both dry land and the ocean floor.

Oceanic crust

 thickest under high mountains, thinnest beneath the ocean. The crust under the ocean.

Continental crust

all the earth under the continents] contains many types of rocks

Mantle

Made of rock that is very hot but solid, divided into layers based on physical characteristics, nearly 3,000 km thick.

Lithosphere

The uppermost part of the mantle, brittle like rock, strong, hard, and rigid, 100 km thick.

Asthenosphere

Material hotter and under increasing pressure, less rigid than rock, more like a 'warm spoon'.

Plastic

Another term for asthenosphere, upper mantle.

Mesosphere

Located beneath the asthenosphere, more rigid due to high pressure.

Transitional zone

Region beneath the asthenosphere, includes the lower mantle.

Outer core

Liquid state, 2,258 km thick, has molten metal surrounding the inner core.

Inner core

Solid ball with a radius of 1,222 km, denser solid ball of metal.

Geographical north

True north, the direction along the Earth's surface.

Magnetic north

The direction that a compass points to as north.

Alfred Wegener

German meteorologist, polar researcher, and geophysicist who proposed the theory of continental drift.

Continental drift

Hypothesis that states the continents once formed a single landmass and have since drifted apart.

Pangea

Supercontinent that existed millions of years ago and broke apart to form the current continents.

Mid-ocean ridges

Mountain ranges formed by seams on the ocean floor, extending into all of Earth's oceans.

Seafloor spreading

Process by which molten material adds new oceanic crust to the ocean floor.

Deep-ocean trenches

Areas where the crust bends downward, often associated with subduction.

Subduction

Process by which part of the ocean floor sinks beneath a deep-ocean trench and back into the mantle.

Tectonic plates

Pieces of the lithosphere that move and interact with each other.

Theory of plate tectonics

The Earth's plates are in slow, constant motion driven by convection currents in the mantle.

Fault

Breaks in the Earth's crust where rocks have slipped past each other.

Divergent boundary

Plates move apart from each other.

Rift Valley

where pieces of Earth’s crust diverge on land causing a deep valley (that can fill with water and create a body of water like an ocean)

Convergent boundary

Two plates come together and collide.

Density

Determines which plate comes out on top in a convergent boundary.

Transform boundary

Two plates slip past each other, moving in opposite directions.

Earthquake

Forces can cause two plates to unlock, resulting in shaking of the Earth's surface.