Earth's Internal Structure and Plate Tectonics - Vocabulary Flashcards

Vocabulary flashcards covering key terms related to Earth's internal structure, plate tectonics, volcanoes, earthquakes, and related geological features.

Crust

The outermost solid layer of the Earth, made of rocks; divided into continental crust (thicker, less dense) and oceanic crust (thinner, more dense).

Mantle

The thick, mostly solid layer between the crust and core; contains the upper mantle (including the plastic-like asthenosphere) and lower mantle.

Core

Earth's densest layer; consists of an outer liquid core and an inner solid core, mainly iron and nickel.

Lithosphere

Rigid outer shell of the Earth comprising the crust and the uppermost mantle; broken into moving tectonic plates.

Asthenosphere

A plastic-like region of the mantle beneath the lithosphere on which the plates move.

Plate Tectonics

Theory that the Earth's crust is divided into moving plates that ride on the mantle; explains earthquakes, volcanoes, and mountain formation.

Tectonic Plate

One of the large rigid slabs that make up the lithosphere and move slowly over the underlying mantle.

Divergent Boundary

A plate boundary where two plates move apart, often creating new crust at mid-ocean ridges.

Convergent Boundary

A plate boundary where two plates collide; can produce subduction, mountains, volcanoes, and earthquakes.

Transform Boundary

A plate boundary where two plates slide past one another horizontally, commonly causing earthquakes.

Mid-Ocean Ridge

An underwater mountain range formed by divergent plate boundaries as new crust is created.

Subduction

The sinking of a denser plate beneath another at a convergent boundary, forming trenches and volcanic activity.

Orogeny

Mountain-building process resulting from crustal compression and uplift during plate collisions.

Island Arc

A curved chain of volcanic islands formed at a subduction zone between oceanic plates.

Volcanic Arc

A chain of volcanoes formed parallel to a subduction zone where magma rises from the mantle.

Hotspot

A location where hot mantle plumes melt rock to form volcanoes away from plate boundaries (e.g., Hawaii).

Shield Volcano

A broad, gently sloping volcano built from low-viscosity lava flows.

Composite Volcano (Stratovolcano)

A tall, steep-sided volcano built from alternating layers of lava, ash, and debris.

Cinder Cone

A small, steep-sided volcano built from volcanic ash and cinders.

Fault

A fracture in the Earth's crust where blocks of rock move relative to each other.

Normal Fault

A fault where the hanging wall moves downward relative to the footwall, due to extension.

Reverse Fault

A fault where the hanging wall moves upward relative to the footwall, due to compression.

Strike-Slip Fault

A fault where rocks slide horizontally past each other; associated with transform boundaries.

Fault Scarp

A steep slope or cliff formed where a fault displaces the ground surface.

Epicenter

The point on the Earth’s surface directly above the focus (hypocenter) of an earthquake.

Focus (Hypocenter)

The point within Earth where an earthquake rupture begins.

Seismograph

An instrument that measures and records seismic waves produced by earthquakes.

P-Waves (Primary Waves)

The first, fastest seismic waves that move by compression and expansion of rocks.

S-Waves (Secondary Waves)

Slower seismic waves that cause shear motion; move perpendicular to wave travel (cannot travel through liquids).

Magnitude

A measure of the energy released by an earthquake.

Intensity

A measure of the effects or severity of an earthquake at a specific location.

Convection Currents

Circulation in the mantle due to heating and cooling that drives plate motions.

Ridge Push

The gravitational force that pushes plates away from mid-ocean ridges as they slide down the elevated ridge.

Slab Pull

The sinking of a subducting plate that pulls the rest of the plate along with it.

Continental Drift

Theory that continents move slowly over time; proposed by Wegener. supports the idea of moving plates.

Pangaea

A supercontinent that existed in the late Paleozoic and early Mesozoic, later broke apart into present continents.

Pacific Ring of Fire

A circum-Pacific belt of earthquakes and volcanoes around the Pacific Ocean due to plate boundaries.

African Plate

A tectonic plate covering Africa and surrounding areas; one of the major lithospheric plates.

North American Plate

A tectonic plate including North America and surrounding regions; interacts with several neighboring plates.

Pacific Plate

The largest tectonic plate, underlying most of the Pacific Ocean and interacting at many boundaries.

Hawaiian Islands

Volcanic islands formed by hotspot volcanism beneath the Pacific Plate, away from plate boundaries.

Folded Mountains

Mountains formed when rock layers are compressed and folded during crustal collision.

Fault-Block Mountains

Mountains formed by blocks of crust uplifted or tilted along faults.