Plate Tectonics and Plate Boundaries - Vocabulary Flashcards (Modules 2-4, 4)

Vocabulary flashcards covering key terms and concepts related to plate tectonics, plate boundaries, evidence for continental drift, and seafloor spreading from the provided notes.

Plate tectonics

Scientific theory that Earth's lithosphere is divided into rigid plates that move slowly over the asthenosphere, driven mainly by mantle convection; interactions at plate edges cause earthquakes, volcanoes, and mountain building.

Lithosphere

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

Asthenosphere

Weak, plastic layer of the mantle beneath the lithosphere on which the plates move.

Convection currents (mantle convection)

Heat-driven circulation in the mantle that drives plate motion.

Divergent boundary

Plate boundary where plates move apart, forming mid-ocean ridges and rift valleys and creating new crust.

Mid-ocean ridge

Undersea mountain range formed by upwelling magma at divergent boundaries; sites of new oceanic crust formation (e.g., Mid-Atlantic Ridge).

Rift valley

Depression formed when continental plates diverge, creating a valley between them.

Convergent boundary

Plate boundary where plates collide; leads to subduction, volcanic arcs, mountain belts, and trenches.

Subduction zone

Region where a denser plate sinks beneath a less dense plate into the mantle.

Trench

Deep underwater trough formed at subduction zones.

Volcanic arc

Chain of volcanoes on the overriding plate at a subduction zone; continental arc on continents, island arc when oceanic.

Island arc

Curved chain of volcanic islands formed by subduction of one oceanic plate beneath another oceanic plate.

Oceanic–Continental convergence

Subduction where an oceanic plate sinks beneath a continental plate, forming a trench and a continental volcanic arc.

Nazca plate

Oceanic plate subducting under the South American plate, forming the Andes.

Transform boundary (strike-slip fault)

Plate boundary where plates slide horizontally past one another; no crust is created or destroyed (e.g., San Andreas Fault).

San Andreas Fault

Major transform boundary between the Pacific and North American plates in California.

Alpine Fault

Transform boundary in New Zealand separating Australian and Pacific plates.

Continental–Continental collision

Convergence of two continental plates with no subduction; formation of large mountain ranges (e.g., Himalayas).

Himalayas

Mountain range formed by the collision of the Indian and Eurasian plates.

Seafloor spreading

Process by which new oceanic crust forms at mid-ocean ridges as older crust moves away; explains the age pattern of the seafloor.

Paleomagnetism

Study of Earth's past magnetic field preserved in rocks, including magnetic stripes indicating past reversals.

Magnetic reversal

Event where Earth's magnetic north and south poles switch places; occurs over thousands to millions of years.

Magnetic stripes

Symmetrical bands of normal and reversed polarity on both sides of mid-ocean ridges, evidence for seafloor spreading.

Alfred Wegener

Scientist who proposed the theory of continental drift and the idea of Pangaea.

Pangaea

Supercontinent that existed before breaking apart into Laurasia and Gondwana.

Laurasia

Northern portion of the broken-up Pangaea, leading to North America, Europe, and Asia.

Gondwana

Southern portion of the broken-up Pangaea, leading to Africa, South America, Antarctica, Australia, and India.

Panthalassa

Global ocean that surrounded Pangaea.

Great Dying

Permian-Triassic extinction event (~252 million years ago), the Earth's largest mass extinction.

Geological fit

Evidence for continental drift: matching coastlines and rock sequences across continents.

Glacier striations

Scratch marks in rocks left by glaciers, used as evidence of past continental positions.

Mesosaurus

Early Permian reptile fossil found on Africa and South America, supporting drift evidence.

Glossopteris

Seed fern fossil found across southern continents, supporting continental drift.

Cynognathus

Permian fossil found on multiple continents, supporting drift evidence.

Lystrosaurus

Permian fossil found across continents, supporting drift evidence.

Seafloor spreading evidence

Symmetric magnetic stripes and younger rocks at ridges supporting seafloor spreading.

Tsunami

Huge ocean wave generated by submarine earthquakes or landslides; Japanese for 'harbor wave'.