Earth's Layers and Plate Tectonics Flashcards

Grade 5 · Science · Flashcards

Key vocabulary for Earth's interior layers and tectonic plate movement.

Flashcards

Crust

Earth's thin outermost solid layer; continental crust (granite) is thicker; oceanic crust (basalt) is thinner and denser.

Mantle

The thick layer between the crust and core; solid rock that flows slowly like plastic over millions of years.

Outer core

Layer of liquid molten iron and nickel (2,900-5,150 km deep) whose movement generates Earth's magnetic field.

Inner core

Earth's solid center of iron and nickel; extremely hot but kept solid by immense pressure.

Tectonic plates

Large, rigid pieces of Earth's crust and upper mantle that float and move on the asthenosphere.

Pangaea

The ancient supercontinent (~250 million years ago) that split apart to form today's continents.

Convergent boundary

Where two plates move toward each other; creates mountains (continent-continent) or volcanoes (oceanic-continental).

Divergent boundary

Where two plates move apart; new crust forms as magma rises to fill the gap.

Transform boundary

Where two plates slide horizontally past each other; causes earthquakes.

Subduction

When a denser oceanic plate dives beneath a less-dense continental plate at a convergent boundary.

Earthquake

Shaking of the ground caused by sudden movement along a fault, usually at plate boundaries.

Volcano

An opening in Earth's crust where magma, ash, and gases escape to the surface.

Mid-ocean ridge

An underwater mountain range at a divergent boundary where new oceanic crust is formed.

Asthenosphere

The partially molten layer of the upper mantle on which tectonic plates slowly move.

Moho discontinuity

The boundary between Earth's crust and mantle, named after seismologist Andrija Mohorovicic.

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