Unit 3 VOCAB Flash Cards Earth Science

Alfred Wegener

German meteorologist and explorer who hypothesized in the early 20th century that continents drift across the Earth's surface.

Continental Drift Theory

The hypothesis proposing that Earth's continents have gradually shifted positions across the globe over geologic time.

Key Evidence for Continental Drift

Matching coastline shapes, identical fossil species across oceans, continuous mountain belts, and ancient glacial or coal deposits in unexpected climates.

Pangaea

The ancient supercontinent proposed by Alfred Wegener in 1915 that included all modern landmasses before they broke apart.

Mantle Convection

The thermal mechanism proposed by Arthur Holmes where heated interior rock ascends, moves laterally, cools, and sinks, driving plate motion.

Seafloor Spreading

The process by which magma ascends at spreading ridges to create new oceanic crust, moving tectonic plates away from one another.

Harry Hess

The scientist who used sonar bathymetry to map the ocean floor, confirming seafloor spreading and mantle convection.

Mid-Ocean Ridges

Extensive undersea mountain chains formed along divergent boundaries that elevate miles above the deep abyssal seafloor.

Rift Zones

Central grabens or valleys located down the center of mid-ocean ridges, situated lower than the adjacent crests.

Deep-Sea Trenches

Vast depressions several miles deep located near continental margins and island arcs, typically associated with subduction and volcanism.

Abyssal Plains

Broad, remarkably flat sections of the deep ocean floor lying between continental rises and mid-ocean ridges.

Guyots

Flat-topped volcanic underwater mountains that were leveled by wave erosion before subsiding deep beneath sea level.

Continental Margin

The transition zone made of continental crust extending from exposed land to the deep ocean basin, constituting over a quarter of ocean space.

Magnetic Striping

Symmetrical alternating patterns of normal and reversed magnetic polarity recorded in basalt on opposite sides of mid-ocean ridges.