Plate Tectonics & Plate Boundaries – Science 10 Lecture

Vocabulary flashcards covering key terms and concepts from the lecture on plate tectonics, seismic activity, volcanoes, mountains, and plate boundaries.

Raisin Theory

Early-20th-century idea that Earth cooled and contracted like a grape turning into a raisin, producing surface wrinkles.

Theory of Isostasy

Clarence Dutton’s 1889 concept that crustal blocks of different density float in gravitational balance; equal surface areas have equal underlying mass.

Plate Tectonics

Theory that Earth’s lithosphere is divided into rigid plates that glide over the mantle, driving continental movement and geologic activity.

Lithospheric Plate

A massive slab of solid rock comprising crust and upper mantle that forms part of Earth’s outer shell.

Continental Drift Theory

Alfred Wegener’s 1915 proposal that continents move over geologic time, once united in supercontinents like Rodinia and Pangaea.

Rodinia

Supercontinent that existed about 1.1 billion years ago, predating Pangaea.

Pangaea

Supercontinent that began breaking apart ~356 Ma, surrounded by the global ocean Panthalassa.

Panthalassa

Ancient ocean that encircled Pangaea; means “all seas.”

Crustal Plates

The ~58 tectonic pieces of Earth’s surface; 15 are major, seven or eight primary.

Continental Crust

Thicker, less-dense, generally older crust forming continents.

Oceanic Crust

Thinner, denser, younger crust underlying oceans.

Seismic Wave

Energy released by earthquakes; includes P-waves, S-waves, and surface waves.

Primary (P) Wave

Fastest seismic wave; compressional motion that travels through solids and liquids.

Secondary (S) Wave

Shear seismic wave; travels only through solids, arrives after P-waves.

Rayleigh Wave

Surface wave with circular rolling motion; causes significant earthquake damage.

Love Wave

Fastest surface wave; moves ground side-to-side horizontally.

Seismograph

Instrument that records seismic waves generated by earthquakes.

Mercalli Intensity Scale

1902 scale by Giuseppe Mercalli rating earthquake effects by observed damage (I–XII).

Richter Scale

Logarithmic magnitude scale developed by Charles F. Richter to quantify earthquake energy.

Tectonic Earthquake

Quake caused by movement along geologic faults at plate boundaries.

Volcanic Earthquake

Seismic event triggered by magma movement beneath a volcano.

Collapse Earthquake

Small quake due to underground cavern or mine collapse.

Explosion Earthquake

Seismic shock produced by nuclear or chemical detonations.

Volcano

Mountain that vents magma from a subsurface reservoir to Earth’s surface.

Mantle Plume

Column of hot mantle rock rising toward the surface, often feeding hotspots.

Hotspot

Surface location with long-lived volcanic activity fed by a mantle plume (e.g., Hawaii).

Orogeny

Process of mountain building through tectonic forces and events.

Geomorphology

Scientific study of Earth’s landforms, including mountains and their evolution.

Mountain Belt / Range

Linear or arcuate chain of mountains formed by tectonic forces, often thousands of kilometers long.

Divergent Boundary

Plate margin where two plates move apart, creating new crust at mid-ocean ridges or continental rifts.

Mid-Ocean Ridge

Undersea mountain chain at divergent boundaries where seafloor spreading forms new oceanic crust.

Convergent Boundary

Plate margin where two plates collide; associated with subduction, trenches, mountains, and volcanic arcs.

Subduction Zone

Region where a denser plate sinks beneath another into the mantle at a convergent boundary.

Transform Fault Boundary

Boundary where plates slide horizontally past each other, producing shallow, powerful earthquakes.

San Andreas Fault

Famous transform fault in California between the Pacific and North American plates.

Oceanic–Oceanic Convergence

Collision of two oceanic plates; creates trenches and volcanic island arcs (e.g., Mariana Trench).

Oceanic–Continental Convergence

Denser oceanic plate subducts under continental plate, forming trenches and continental volcanic arcs.

Continental–Continental Convergence

Collision of two buoyant continental plates, building high mountains (e.g., Himalayas).

Island Arc

Curved chain of volcanic islands formed above a subducting oceanic plate at an oceanic–oceanic boundary.

Trench

Deep, narrow depression in the ocean floor created by subduction at convergent boundaries.

East African Rift

Continental divergent boundary where Africa is splitting into two plates.

Mid-Atlantic Ridge

Mid-ocean ridge running down the Atlantic; classic example of a divergent boundary.

East Pacific Rise

Fast-spreading mid-ocean ridge in the eastern Pacific Ocean.

Ridge-Ridge Transform Fault

Transform fault linking two divergent ridge segments (e.g., Dead Sea Transform).

Ridge-Trench Transform Fault

Transform fault connecting a spreading ridge to a subduction trench (e.g., Queen Charlotte Fault).

Trench-Trench Transform Fault

Transform fault linking trenches from two convergent margins (e.g., Alpine Fault, New Zealand).