Earth 4_L3_ Plate Tectonics (cont.)

Plate Tectonics

The theory explaining the structure and movement of the Earth's lithosphere, which consists of several large plates.

Lithospheric Plates

Sections of the Earth's lithosphere that move and interact with one another, leading to geological activity.

Continental Drift

The hypothesis that continents have moved across the Earth's surface over geological time.

Divergent Boundaries

Plate boundaries where two tectonic plates move away from each other, forming mid-ocean ridges.

Convergent Boundaries

Plate boundaries where two plates collide, causing subduction or mountain formation.

Transform Boundaries

Plate boundaries where two plates slide past each other horizontally, leading to earthquakes.

Asthenosphere

The semi-fluid layer of the mantle beneath the lithosphere, allowing for the movement of lithospheric plates.

Hotspot Volcanism

Volcanic activity that occurs at the locations of mantle plumes, independent of plate boundaries.

Paleomagnetism

The study of the magnetic properties of rocks to determine historical changes in Earth's magnetic field.

Apparent Polar Wander

The perceived movement of the magnetic poles over time, suggesting that continents have moved.

Seafloor Spreading

The process by which new oceanic crust forms at mid-ocean ridges and gradually moves away from the ridge.

Magnetic Reversals

Events when Earth’s magnetic field changes direction, recorded by the orientation of magnetic minerals in volcanic rocks.

Continental-Oceanic Convergence

A type of convergent boundary where oceanic crust subducts beneath continental crust, forming volcanoes.

Earthquakes

Seismic events that occur when stress builds up at plate boundaries and is suddenly released.

Fringing Reef

A type of coral reef that grows around the flanks of active volcanic islands.

Barrier Reef

A coral reef that forms as an island subsides, creating a lagoon between the reef and the island.

Atoll

A ring-shaped coral reef that forms when an island sinks below sea level.

Mantle Convection

The movement of the Earth's mantle due to heat transfer, driving the motion of tectonic plates.

Ridge Push

A tectonic process that occurs at mid-ocean ridges, contributing to plate movement.

Slab Pull

A process where a denser oceanic plate subducts under a lighter continental plate, pulling the rest of the plate along.

Geological History

The history of the Earth, recorded in its stratified rocks and geologic formations.

Oceanic Crust

The part of Earth's lithosphere that underlines the ocean basins, primarily composed of basalt.

Continental Crust

The part of Earth's lithosphere that forms the continents, primarily composed of granite.

Subduction Zone

An area where one tectonic plate moves under another, creating deep ocean trenches and volcanic arcs.

Orogeny

The process of mountain formation, typically through tectonic plate collisions.

Explosive Volcanism

Volcanic eruptions characterized by the violent release of gas and ash, often occurring at convergent boundaries.

Mid-Ocean Ridge

An underwater mountain range formed by seafloor spreading at divergent boundaries.

Tsunami

A series of ocean waves caused by the sudden displacement of water, often due to earthquakes.

Lithosphere-Asthenosphere Boundary

The boundary between the rigid lithosphere and the semi-fluid asthenosphere, crucial for tectonic movement.

Earth's Inner Core

The solid innermost layer of the Earth, composed primarily of iron and nickel.

Earth's Outer Core

The fluid layer of the Earth's core that lies beneath the mantle and surrounds the inner core.

Geothermal Gradient

The rate at which temperature increases with depth in the Earth's crust.

Seismic Waves

Waves of energy that travel through the Earth's layers, often caused by earthquakes.

Rift Valley

A lowland region formed by tectonic plates moving apart, often associated with divergent boundaries.