Earth 4_L4_ TectonicsII_seafloor

Plate Tectonics

The theory explaining the structure and motion of the Earth's lithosphere, which is divided into tectonic plates.

Divergent boundaries

Tectonic plate boundaries where plates move apart, often resulting in mid-ocean ridges and continental rifts.

Convergent boundaries

Tectonic plate boundaries where plates collide, leading to subduction zones, mountain ranges, or deep ocean trenches.

Transform boundaries

Tectonic plate boundaries where plates slide past one another, resulting in faults such as the San Andreas Fault.

Subduction zones

Areas where one tectonic plate slides beneath another, often leading to volcanic activity.

Seafloor spreading

The process by which new oceanic crust is formed through volcanic activity at mid-ocean ridges.

Continental margins

The zones of interaction between continental and oceanic crust, can be passive or active.

Abyssal plains

Deep, flat areas of the ocean floor, typically found at the bottom of the ocean and formed by sediment deposition.

Mantle plumes

Stationary vertical columns of hot rock that rise through the mantle, often creating hotspots for volcanic activity.

Bathymetry

The study of underwater depth of ocean floors or lake floors, measuring the depth and shape of the ocean floor.

Echo sounder

An instrument using sound waves to measure water depth, helping in bathymetric mapping of the ocean floor.

Sonar

Technology that uses sound propagation to navigate, communicate, or detect objects underwater.

Turbidity currents

Underwater flows of sediment-laden water that can erode the seabed and lead to the formation of submarine canyons.

Hawaiian hotspot

A volcanic hotspot in the middle of the Pacific Plate, responsible for forming the Hawaiian Islands.

Mid-ocean ridges

Underwater mountain ranges formed by plate tectonics, where seafloor spreading occurs.

Oceanic crust

The outermost layer of the Earth beneath the oceans, typically thinner and denser than continental crust.

Continental rifting

The process by which a continent splits into two or more smaller landmasses, often creating a rift valley.

Seismic reflection profiling

A method used to study the structure of the seabed and underlying rock layers by analyzing reflected sound waves.

Hotspot

A location on the Earth's surface that has experienced prolonged volcanic activity due to a mantle plume.

The Wilson Cycle

A model that describes the cyclical nature of ocean basin development, opening and closure.

Gravity anomaly

The difference between the observed gravitational field and the predicted gravitational field, used to detect seafloor features.

Rift Valley

A lowland region formed by the divergence of tectonic plates, often characterized by steep walls and a linear shape.

Trench

A deep, narrow depression in the ocean floor formed by subduction of one tectonic plate beneath another.

Island arc

A curved chain of volcanic islands that form along a convergent plate boundary, usually associated with subduction zones.

Volcanic arc

A chain of volcanoes that forms parallel to a subduction zone due to the melting of the subducted plate.

Fault

A fracture in the Earth's crust along which movement has occurred, often associated with earthquakes.

Earthquake

The shaking of the Earth's surface caused by sudden release of energy in the Earth's lithosphere.

Lithosphere

The rigid outer layer of the Earth, consisting of the crust and upper mantle.

Asthenosphere

The semi-fluid layer beneath the lithosphere that allows tectonic plates to move.

Pangaea

A supercontinent that existed around 335 million years ago, where all continents were joined together.

Ophiolite

A section of the Earth's oceanic crust and the underlying upper mantle that has been uplifted and exposed.