Plate Tectonics – Science 10 Lecture

50 English vocabulary flashcards summarizing key terms and definitions from the Science 10 lesson on Plate Tectonics.

Plate Tectonics Theory

The modern scientific theory that Earth’s lithosphere is divided into moving plates whose interactions cause earthquakes, volcanoes, and mountain building.

Continental Drift Theory

Alfred Wegener’s 1915 idea that continents were once joined in a supercontinent (Pangaea) and have since drifted apart.

Pangaea

A supercontinent that existed about 250 million years ago, containing all of Earth’s landmasses before they separated.

Alfred Wegener

German meteorologist–geophysicist who proposed the Continental Drift Theory in 1915.

Lithosphere

Earth’s rigid outer layer consisting of the crust and uppermost mantle, broken into tectonic plates.

Asthenosphere

The semi-molten, ductile portion of the upper mantle that allows lithospheric plates to move.

Convection Currents

Circular motions in the mantle caused by heat from Earth’s interior, driving plate movement.

Seafloor Spreading

Harry Hess’s concept that new oceanic crust forms at mid-ocean ridges and moves outward, pushing plates apart.

Harry Hess

Geologist who advanced plate tectonics by proposing seafloor spreading in 1962.

J. Tuzo Wilson

Canadian geophysicist who introduced transform faults and hotspots, strengthening plate tectonic theory.

Mid-Ocean Ridge

An underwater mountain chain where seafloor spreading creates new oceanic crust.

Magnetic Striping

Symmetrical patterns of magnetic minerals on either side of mid-ocean ridges, recording geomagnetic reversals and supporting seafloor spreading.

Jigsaw Fit of the Continents

Observation that shorelines (e.g., South America and Africa) match like puzzle pieces, indicating past connection.

Fossil Evidence

Identical fossils found on widely separated continents, supporting the idea they were once joined.

Mesosaurus

Freshwater reptile whose fossils on both South America and Africa validate continental drift.

Glossopteris

Extinct seed fern whose fossils across South America, Africa, India, Australia, and Antarctica support Pangaea.

Geologic Evidence

Matching rock types and mountain ranges on different continents indicating former proximity.

Appalachian Mountains

North American range whose rock structures match mountains in Greenland, Britain, and Norway, evidencing continental drift.

Climate Evidence

Signs (e.g., glacial grooves, coal in Antarctica) showing continents have shifted across climatic zones.

Glacial Grooves

Scratches left by moving ice found in now-warm regions, implying those lands were once near poles.

Coal Deposits in Antarctica

Tropical-origin coal found on the polar continent, indicating its past equatorial position.

Ring of Fire

Seismically active belt surrounding the Pacific Ocean where numerous earthquakes and volcanoes occur.

Mid-Atlantic Ridge

Divergent plate boundary down the Atlantic where seafloor spreading forms new crust and moderates quakes.

African Rift Valley

Continental divergent boundary in East Africa where plates pull apart, creating volcanic and earthquake activity.

Alpide Belt

Seismic and mountain-forming zone across southern Eurasia, including the Alps and Himalayas.

Earthquake Distribution

Pattern showing most quakes occur along plate boundaries rather than randomly across Earth.

Volcanic Distribution

Global pattern in which most volcanoes align with convergent or divergent plate boundaries.

Mountain Range Formation

Result of plate convergence and uplift, producing belts like the Himalayas or the Andes.

Convergent Boundary

Plate margin where two plates collide, causing subduction, volcanic arcs, or mountain building.

Divergent Boundary

Plate margin where two plates move apart, forming rift valleys and mid-ocean ridges.

Transform Boundary

Plate margin where plates slide horizontally past one another, generating strike-slip earthquakes.

Oceanic Crust

Dense basaltic portion of Earth’s crust forming the ocean floors.

Continental Crust

Thicker, less-dense granitic crust composing Earth’s continents.

Tectonic Plate

Large, rigid slab of lithosphere that moves over the asthenosphere.

Earth’s Mantle

Layer of hot, solid to semi-molten rock beneath the crust, driving plate motion via convection.

Mantle Convection

Heat-driven flow within the mantle that moves tectonic plates.

Plate Boundary

Region where two tectonic plates meet and interact, often causing geologic events.

Supercontinent

A single landmass formed from the merger of several continents, like Pangaea.

Plate Movement

The relative motion of tectonic plates, measured in centimeters per year.

Scientists' Initial Skepticism

Early 20th-century refusal to accept continental drift due to lack of a movement mechanism.

1915 Publication of Continental Drift

Year Alfred Wegener released “The Origin of Continents and Oceans,” proposing Pangaea.

1970s Acceptance of Plate Tectonics

Decade when magnetic data, seafloor spreading, and convection models led to widespread scientific agreement.

Radioactivity Discovery (1896)

Finding that Earth’s interior is hot, providing energy for mantle convection and plate motion.

Bees Ultraviolet Vision

Trivia noting bees see UV patterns on flowers invisible to humans, aiding pollination.

Iceland

Island straddling the Mid-Atlantic Ridge, illustrating active divergent boundary volcanism.

Chilean Earthquake

Example of powerful quakes at a convergent boundary between the Nazca and South American Plates.

Mount Everest

World’s highest peak formed by collision of the Indian and Eurasian plates.

Earth Science

Field studying Earth’s physical constitution and processes, including geology, meteorology, and oceanography.

Earthquake

Sudden release of energy in Earth’s crust creating seismic waves, often at plate boundaries.

Volcano

Opening in Earth’s crust through which molten rock, ash, and gases are expelled.