Continental Drift, Geological Theories & Plate Tectonics

Vocabulary flashcards summarizing key terms, evidence, people, and theories related to continental drift, seafloor spreading, paleomagnetism, and the catastrophism–uniformitarianism debate.

Continental Drift

The hypothesis that Earth’s continents were once joined and have since moved apart over geologic time.

Pangea

The supercontinent that existed about 200 million years ago and later split to form today’s continents.

Panthalassa

The vast global ocean that surrounded Pangea.

Alfred Wegener

German scientist who proposed the continental-drift hypothesis in 1912.

Lystrosaurus

Triassic land-dwelling reptile whose fossils on several continents support continental drift.

Cynognathus

Triassic land reptile; its cross-continental fossils are evidence for Pangea.

Glaciation

Intervals of extensive ice advance; matching glacial deposits on distant continents back continental drift.

Rift Valley of Africa

Linear geologic trench interpreted as modern evidence of continental breakup.

Appalachian Mountains–Greenland Belt

Continuous mountain chain whose matching rock ages/types link North America and Greenland in past configurations.

Paleoclimatology

Study of ancient climates inferred from geological and fossil evidence.

Paleomagnetism

Study of Earth’s past magnetic field recorded in rocks; reveals magnetic reversals and supports seafloor spreading.

Mid-Atlantic Ridge

Submarine mountain range mapped in 1947; site of new crust formation by seafloor spreading.

Seafloor Spreading

Harry Hess’s hypothesis that new oceanic crust forms at mid-ocean ridges and moves outward, driving continental drift.

Harry Hess

Geologist who, in the 1960s, proposed seafloor spreading as the mechanism for continental movement.

Magnetic Reversal

Periodic switch in Earth’s magnetic polarity recorded symmetrically in oceanic crust, confirming seafloor spreading.

Catastrophism

Geologic view that Earth’s history is shaped by infrequent, sudden, violent events and floods.

Uniformitarianism

Principle that present-day geologic processes operating at similar rates have shaped Earth through deep time.

James Hutton

Scientist who formulated the concept of uniformitarianism in his work ‘Theory of the Earth.’

Charles Lyell

Author of ‘Principles of Geology’; expanded uniformitarianism and influenced Darwin.

Georges Cuvier

French paleontologist who championed catastrophism after observing fossil succession and extinctions.

Mantle Convection Current

Heat-driven circulation within Earth’s mantle that transports material and contributes to plate movement.

Slab Pull Theory

Mechanism where the weight of a subducting plate edge drags the rest of the plate toward a trench.

Triassic Period

Geologic period (~252–201 mya) during which fossils such as Lystrosaurus and Cynognathus lived.

Seafloor Age Disparity

Observation that oceanic rocks (≤150 Ma) are much younger than continental rocks (~4 Ga).

Actualism

Methodological aspect of uniformitarianism that uses present-day processes to interpret past events.

Paroxysms

Sudden, intense geologic events emphasized by catastrophists as primary earth-shaping forces.

Principles of Geology

Seminal 1830–33 work by Charles Lyell that argued convincingly for uniformitarianism.

Megatherium

Extinct giant ground sloth whose fossils were described by Cuvier, illustrating past life and extinctions.