Science 10 – Plate Boundaries & Related Concepts

Vocabulary flashcards covering key terms, processes, boundary types, examples, and geologic features related to Plate Tectonics and Plate Boundaries.

Plate Tectonics Theory

Scientific theory stating that Earth’s lithosphere is broken into moving plates that interact at their boundaries.

Lithosphere

Rigid outer layer of Earth composed of the crust and uppermost mantle; forms the tectonic plates.

Asthenosphere

Partially molten, plastic layer of the upper mantle on which tectonic plates float and move.

Plate Boundary

Region where two tectonic plates meet and interact: convergent, divergent, or transform.

Convergent Boundary

Plate boundary where two plates move toward each other, causing collision or subduction.

Divergent Boundary

Plate boundary where two plates move apart, creating new crust through rifting or seafloor spreading.

Transform Boundary

Plate boundary where two plates slide horizontally past each other, generating shear stress.

Compression (Compressional Stress)

Stress produced at convergent boundaries as plates push together.

Tension (Tensional Stress)

Stress produced at divergent boundaries as plates pull apart.

Shear Stress

Side-to-side stress acting at transform boundaries.

Subduction Zone

Area where one plate sinks beneath another into the mantle, generating trenches, earthquakes, and volcanoes.

Trench

Deep, narrow depression in the ocean floor formed at subduction zones; deepest parts of the ocean.

Mariana Trench

Earth’s deepest ocean trench formed by Pacific Plate subducting beneath the Philippine Sea Plate.

Volcanic Island Arc

Curved chain of volcanic islands formed above a subduction zone where one oceanic plate descends beneath another.

Continental Arc

Chain of volcanoes on continental crust formed where an oceanic plate subducts beneath a continental plate.

Folded Mountains

Mountain ranges created by compression and folding of continental crust during continental-continental convergence.

Himalayas

Example of folded mountains produced by collision of the Indian Plate and Eurasian Plate (C-C convergence).

Aleutian Islands

Volcanic island arc created by Pacific Plate subducting beneath North American Plate (O-O convergence).

San Andreas Fault

Major transform (strike-slip) fault between the Pacific Plate and North American Plate in California.

Great Rift Valley

Continental rift valley in East Africa formed by divergent motion between Nubian, Somalian, and Arabian plates.

Mid-Ocean Ridge

Undersea mountain chain formed by seafloor spreading at oceanic-oceanic divergent boundaries.

Mid-Atlantic Ridge

Segment of the global mid-ocean ridge between the North American and Eurasian Plates & South American and African Plates.

Seafloor Spreading

Process of new oceanic crust forming at mid-ocean ridges and moving outward from the ridge axis.

Continental-Continental Convergence

Collision of two continental plates; neither subducts, producing high mountains but little volcanism.

Continental-Oceanic Convergence

Meeting of continental and oceanic plates; denser oceanic plate subducts, creating trenches and continental arcs.

Oceanic-Oceanic Convergence

Collision of two oceanic plates; older, denser plate subducts, producing trenches and volcanic island arcs.

Continental-Continental Divergence

Continental rifting where a continent splits, forming rift valleys and potentially new ocean basins.

Oceanic-Oceanic Divergence

Seafloor spreading between two oceanic plates that forms new crust and mid-ocean ridges.

Oceanic-Continental Divergence

Rare divergent setting where oceanic and continental crust pull apart, forming rift valleys that may evolve into oceans.

Hotspot

Fixed plume of magma rising from deep mantle, creating intra-plate volcanoes like the Hawaiian Islands.

Deep-Focus Earthquake

Earthquake with focus deeper than 300 km, typically occurring within subducting slabs at convergent boundaries.

Shallow-Focus Earthquake

Earthquake occurring at depths less than 70 km; common along all plate boundaries, especially transform faults.

Strike-Slip Fault

Fault where blocks of crust move horizontally past each other; characteristic of transform boundaries.

Rift Valley

Linear lowland between highlands formed by divergent tectonic activity on continental crust.

Seismic Activity

Frequency and magnitude of earthquakes in a region, often concentrated along plate boundaries.

Volcanic Activity

Eruptive processes associated with magma reaching the surface, common at subduction zones and divergent ridges.

Nazca Plate

Oceanic plate subducting beneath the South American Plate, forming Andes Mountains and Peru-Chile Trench.

Juan de Fuca Plate

Small oceanic plate subducting beneath the North American Plate off the Pacific Northwest, producing Cascadia volcanism.

Philippine Sea Plate

Oceanic plate interacting with Eurasian Plate, forming Philippine Trench and volcanic arcs.

Arabian Plate

Tectonic plate moving away from African Plate, contributing to Red Sea and East African rifting.

Somalian Plate

Plate splitting from Nubian (African) Plate along East African Rift system.

Nubian Plate

Western portion of African Plate involved in East African rifting.

Plate Boundary Map

Diagram showing global distribution and types of plate boundaries, used to predict geologic events.

Seismic and Volcanic Evidence

Patterns of earthquakes and volcanoes that help infer the type of plate boundary in a region.

Compressional Mountains

Mountain ranges produced by crustal shortening at convergent boundaries, such as the Andes and Himalayas.

Transform Fault Earthquake

Shallow, often strong earthquake generated by horizontal movement along a transform boundary.

Seafloor Age Pattern

Symmetrical increase in ocean floor age away from mid-ocean ridges, evidence for seafloor spreading.