Evidences of Plate Movement – Key Vocabulary

25 vocabulary flashcards covering essential terms related to continental drift, seafloor spreading, magnetic evidence, and plate tectonics.

Continental Drift Theory

The hypothesis that Earth’s continents were once joined in a single landmass and have since slowly moved to their present positions.

Alfred Wegener

German scientist who first formally proposed the Continental Drift Theory in 1912.

Glossopteris

An extinct seed fern whose widespread fossils across southern continents provided strong support for continental drift.

Mesosaurus

A Permian-age freshwater reptile whose fossils in both South America and Africa indicate the continents were once connected.

Lystrosaurus

Triassic land reptile fossil found on several southern continents, reinforcing the idea of Gondwanaland.

Cynognathus

Triassic terrestrial reptile whose fossils on separate continents helped Wegener argue for continental drift.

Pangaea

The supercontinent that existed about 225 million years ago before breaking apart into smaller landmasses.

Gondwanaland

The southern portion of Pangaea that included South America, Africa, Antarctica, India, and Australia.

Laurasia

The northern part of Pangaea composed mainly of North America, Europe, and Asia.

Seafloor Spreading Theory

Idea that new oceanic crust forms at mid-ocean ridges and moves outward, causing oceans to widen.

Harry Hess and Robert Dietz

Geologists who independently introduced and developed the concept of seafloor spreading in the early 1960s.

Mid-Ocean Ridge

Continuous underwater mountain chain where magma rises, cools, and creates new oceanic lithosphere.

Magnetic Reversal

A switch in Earth’s magnetic poles; evidence is preserved in alternating polarity bands on the seafloor.

Hotspot

A fixed mantle source of heat and magma that forms chains of volcanoes as a tectonic plate moves over it.

Mantle Plume

A narrow column of hot, buoyant mantle rock that rises to feed a hotspot at Earth’s surface.

Plate Tectonics Theory

The unifying model stating the lithosphere is broken into moving plates driven by mantle processes.

Lithosphere

The rigid outer shell of Earth, consisting of crust and uppermost mantle, divided into tectonic plates.

Crustal Age

The relative age pattern of oceanic crust, which increases with distance from a mid-ocean ridge.

Magnetic Striping

Symmetrical bands of normal and reversed magnetism in oceanic basalt that record seafloor spreading.

Subduction Zone

A convergent boundary where one tectonic plate bends downward and sinks into the mantle beneath another plate.

Divergent Boundary

A plate boundary where two tectonic plates move apart, generating new lithosphere (e.g., mid-ocean ridges).

Convergent Boundary

A plate boundary where two plates move toward each other, often forming trenches, mountains, and volcanic arcs.

Deep-Sea Trench

A long, narrow oceanic depression marking a subduction zone and containing some of the oldest oceanic crust.

Hawaiian Hotspot Track

A chain of progressively older volcanic islands and seamounts that traces Pacific Plate motion over a stationary hotspot.

Paleomagnetism

The study of ancient magnetic records in rocks, used to reconstruct past plate motions and magnetic reversals.