Lecture 3: Seafloor Spreading & Plate Tectonics (Vocabulary)

Vocabulary flashcards covering seafloor spreading, plate tectonics, paleomagnetism, and related concepts from the lecture notes.

Seafloor spreading

The process by which new oceanic crust forms at mid-ocean ridges and moves older crust away from the ridge due to mantle convection.

Mid-ocean ridge

An underwater mountain chain where new oceanic crust is produced by upwelling mantle.

Mantle convection

Heat-driven circulation in Earth's mantle that drives plate tectonics and the creation/pulling apart of seafloor.

Alfred Wegener

German scientist who proposed continental drift and the idea that continents were once connected.

Continental drift

Hypothesis that Earth's continents have moved relative to one another over geologic time.

Pangaea

The ancient supercontinent that assembled all landmasses and later broke apart.

Marie Tharp

Cartographer/oceanographer whose maps revealed the global mid-ocean ridge system and seafloor features.

The Great Rift

Term used for the global mid-ocean ridge system that runs through the world’s oceans.

Harry Hess

Geologist who proposed seafloor spreading and supported the plate tectonics framework.

Plate tectonics

Theory that Earth's lithosphere is divided into moving plates whose interactions shape continents and oceans.

Magnetic declination

Angle between geographic north and magnetic north at a location.

Magnetic inclination (dip)

Angle between Earth's magnetic field lines and a horizontal plane; varies with latitude.

Magnetic north pole

Location of Earth's magnetic north, which moves over time and is not the geographic north.

Geographic north pole

The northern end of Earth's axis of rotation; fixed reference for geographic coordinates.

Paleomagnetism

Study of past magnetic field information preserved in rocks as they form and solidify.

Virtual Geomagnetic Pole (VGP)

Estimated past position of the magnetic pole inferred from paleomagnetic data.

Apparent Polar Wander Path (APWP)

Composite path showing how paleomagnetic poles appear to move relative to continents over time.

Magnetic polarity reversal

Event where Earth's magnetic field flips, changing which pole is magnetic north.

Magnetic stripes

Parallel bands of normal and reversed magnetic polarity on the ocean floor, reflecting past reversals.

Amasia

Proposed future supercontinent formed by the collision of the Americas with Asia.

Pangea Proxima

Proposed future supercontinent where most current continents collide again.

Global Positioning System (GPS) monitoring of plates

Using GPS stations to measure precise, ongoing movements of tectonic plates.

Oceanic lithosphere

Rigid outer shell of the Earth (crust and upper mantle) that forms at mid-ocean ridges and moves via plate tectonics.

Continental drift evidence

Evidence such as coastline fit, fossil distributions, and rock correlations that support plate movements.

The scientific method

Systematic process of observing, forming hypotheses, testing with data, and developing theories.

Magnetic reversal frequency

Approximate average interval between geomagnetic reversals (about 200,000 to 300,000 years).