Plate Tectonics – Grade 10 Science Vocabulary

Vocabulary flashcards covering the key terms and concepts from the Plate Tectonics lecture.

Plate Tectonics

The scientific theory that Earth’s lithosphere is broken into moving plates whose interactions create major landforms and geologic events.

Lithosphere

Rigid outer layer of Earth composed of the crust and the uppermost solid mantle; divided into tectonic plates.

Asthenosphere

Plastic, partially molten layer of the upper mantle beneath the lithosphere on which tectonic plates move.

Crust

Earth’s outermost solid layer, 0–100 km thick, consisting of continental and oceanic types.

Continental Crust

Thicker (but less dense) portion of Earth’s crust forming the continents.

Oceanic Crust

Thinner (but denser) portion of Earth’s crust underlying ocean basins.

Tectonic Plate

A rigid section of the lithosphere that moves over the asthenosphere.

Plate Boundary

The margin where two tectonic plates meet and interact, often marked by earthquakes and volcanoes.

Convergent Boundary

A plate margin where two plates move toward each other, producing subduction, mountains, trenches, and strong quakes.

Divergent Boundary

A plate margin where two plates move apart, forming rift valleys, mid-ocean ridges, and new crust.

Transform Fault Boundary

A plate margin where plates slide horizontally past each other, generating earthquakes (e.g., San Andreas Fault).

Subduction

The process by which one tectonic plate sinks beneath another into the mantle at a convergent boundary.

Trench

A deep, narrow depression on the ocean floor formed where a subducting plate bends downward.

Volcanic Arc

A curved chain of volcanoes on a continent above a subducting plate (oceanic-continental convergence).

Island Arc

A curved chain of volcanic islands that forms on the overriding oceanic plate at an oceanic-oceanic convergent boundary.

Mid-Ocean Ridge

An underwater mountain range formed by magma rising at an oceanic-oceanic divergent boundary.

Seafloor Spreading

The creation of new oceanic crust at mid-ocean ridges as plates diverge.

Rift Valley

A linear, steep-walled depression formed by continental-continental divergence (e.g., East African Rift).

Mountain Range (Young Fold Mountains)

High, folded mountains produced mainly by continental-continental convergence (e.g., Himalayas).

Earthquake

Rapid shaking of Earth’s crust caused by sudden release of energy along faults or plate boundaries.

Focus (Hypocenter)

The point inside Earth where an earthquake originates.

Epicenter

The point on Earth’s surface directly above an earthquake’s focus.

Volcano

An opening in Earth’s crust through which molten rock, ash, and gases erupt.

Seismograph (Seismometer)

An instrument that detects and records the intensity and duration of earthquakes.

Mantle

The thick, middle layer of Earth between crust and core, composed mainly of solid and partially molten rock.

Core

Earth’s innermost layer, consisting of a liquid outer core and solid inner core rich in iron and nickel.

Outer Core

Liquid layer of Earth’s core, whose movement generates the magnetic field.

Inner Core

Solid, dense center of Earth composed mainly of iron and nickel.

Accretionary Wedge

Scraped-off sediments and oceanic crust accumulating at a subduction zone trench.

Forearc Basin

A sediment-filled depression between a trench and a volcanic or island arc in a subduction zone.

Backarc Region

Area behind a volcanic or island arc that may experience extension and basin formation.

Ocean Basin

A broad low area of Earth’s surface covered by ocean water, often formed by prolonged divergence.