Lesson 1 & 2: Tectonic Plates, Plate Boundaries, Hazards, and Earth's Interior (Vocabulary)

Vocabulary flashcards covering key terms related to tectonic plates, plate boundaries, driving forces, hazards, and Earth's interior.

Tectonic Plate

A massive, irregularly shaped slab of solid rock that makes up Earth's lithosphere and crust; consists of continental and oceanic lithosphere.

Continental Plate

A tectonic plate composed mainly of continental crust; thicker and less dense.

Oceanic Plate

A tectonic plate composed mainly of oceanic crust; thinner and more dense.

Plate Boundary

The edges where two tectonic plates meet (often likened to puzzle-piece boundaries).

Convergent Boundary

Where two plates move toward each other; can form mountains, volcanic arcs, and earthquakes; includes subduction zones.

Subduction Zone

A region where one plate dives beneath another into the mantle.

Orogenic Belt

A belt of terrain formed by mountain-building processes.

Orogenesis

The process of mountain-building and mountain-range formation.

Oceanic Trench

A long, narrow depression on the ocean floor formed in subduction zones.

Mariana Trench

The deepest known ocean trench, located in the western Pacific Ocean.

Andes Mountains

A mountain range formed largely by subduction of the Nazca Plate beneath the South American Plate.

Cascade Range

A mountain range in western North America formed by subduction-related volcanism.

The Alps

A major European mountain range formed by continental-continental collision.

Himalayas

The towering mountain range formed by the collision of the Indian Plate with the Eurasian Plate.

Divergent Boundary

Where two plates move apart; magma rises to fill the gap, creating new crust and often rift valleys and mid-ocean ridges.

Rift Valley

A wide valley formed as continental plates pull apart.

Mid-oceanic Ridge

An underwater mountain ridge formed by seafloor spreading at divergent boundaries.

Seafloor Spreading

The process by which new oceanic crust forms as magma rises at divergent boundaries and pushes plates apart.

East African Rift Valley

A current example of continental rifting where the African Plate is splitting.

Transform Boundary

Where two plates slide past one another horizontally; often produces earthquakes.

Normal Fault

A dip-slip fault where the hanging wall moves down relative to the footwall (extension).

Reverse Fault

A dip-slip fault where the hanging wall moves up relative to the footwall (compression).

Strike-slip Fault

A fault where blocks slide horizontally past one another with little vertical movement.

Dip-slip

Movement of faults along the angle (dip) of the fault plane.

Dip

Angle of movement along a fault plane.

Slip

The amount of movement along a fault surface.

Thrust Fault

A low-angle reverse fault (dip of 45 degrees or less).

San Andreas Fault

A famous transform boundary in California where the Pacific and North American plates slide past each other.

Oceanic-oceanic Convergence

Subduction of an oceanic plate beneath another oceanic plate, forming island arcs and trenches.

Oceanic-continental Convergence

Denser oceanic plate subducts beneath the lighter continental plate, forming trenches and volcanic arcs.

Continental-continental Convergence

Collision of two continental plates; no subduction, mountains crumple and rise.

Primary Plates

The seven major tectonic plates on Earth.

Eurasian Plate

One of the primary tectonic plates covering Europe and Asia.

Australian Plate

A primary tectonic plate covering Australia and surrounding regions.

Pacific Plate

A primary plate beneath the Pacific Ocean; one of the largest tectonic plates.

North American Plate

A primary plate covering North America and adjacent areas.

South American Plate

A primary plate covering South America and parts of the Atlantic Ocean.

African Plate

A primary plate covering Africa and surrounding oceanic crust.

Antarctic Plate

A primary plate covering Antarctica and surrounding oceanic crust.

Secondary Plates

Smaller tectonic plates that interact with the primary plates.

Juan de Fuca Plate

A secondary plate off the western coast of North America.

Nazca Plate

A secondary plate subducting beneath South America.

Cocos Plate

A secondary plate located west of Central America; subducting beneath the Caribbean and C. American plates.

Caribbean Plate

A secondary plate beneath the Caribbean region.

Philippine Sea Plate

A secondary plate located in the western Pacific Ocean.

Arabian Plate

A secondary plate covering the Arabian Peninsula.

Indian Plate

A secondary plate that collided with Asia to form the Himalayas.

Scotia Plate

A small plate off the southern tip of South America.

Mantle Convection

Heat-driven motion in the mantle that moves tectonic plates via convection currents.

Slab Pull

Gravitational sinking of a subducting plate that helps pull the rest of the plate with it.

Slab Suction

Suction force in the mantle that helps pull plates toward subduction during collision.

Ridge Push

Upward push of the rising ridge; gravity helps push older lithosphere away from the ridge.

Slab Resistance

Friction and other forces that resist subduction of a slab.

Collisional Resistance

Resistance to subduction when a heavy plate resists descent due to friction.

Transform Fault Resistance

Friction opposing plate movement at transform boundaries.

Drag Force

Frictional force that resists the movement of lithospheric plates.

Earthquake

A sudden, intense shaking of the ground caused by energy release in rocks.

Hypocenter (Focus)

The point within Earth where rocks first break and seismic energy is released.

Epicenter

The point on Earth's surface directly above the hypocenter.

Intraplate Earthquakes

Earthquakes that occur within a single tectonic plate, not at plate boundaries.

Volcanic Eruption

Magma rises and erupts at the surface; associated with plate boundaries and magma accumulation.

Pyroclastic Flows

Fast-moving, hot avalanches of volcanic ash and gas.

Lahars

Volcanic mudflows created when volcanic debris mixes with water.

Ashfall

Volcanic ash deposited from an eruption.

Active Volcano

A volcano that has erupted recently or is likely to erupt again.

Dormant Volcano

A volcano that is not currently erupting but could erupt again.

Extinct Volcano

A volcano that is not expected to erupt again.

Landslide

Gravity-driven movement of rock and soil down a slope.

Tsunami

Massive ocean waves triggered by underwater earthquakes or volcanic eruptions.

Pacific Ring of Fire

A horseshoe-shaped zone around the Pacific Ocean with many active volcanoes and earthquakes.

Mid-Atlantic Ridge

An underwater mountain range where seafloor spreading occurs between the Americas, Europe, and Africa.

East African Rift Valley

A continental rift zone in East Africa where plate tectonics separates the African Plate.

Himalayan Belt

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

Distribution of Earthquake Zones

Regions with prominent earthquake activity, including the Pacific Ring of Fire, Himalayan Belt, and Mid-Atlantic Ridge.

Distribution of Mountain Belts

Major mountain ranges formed by plate interactions (e.g., Himalayas, Andes, Rockies, Alps).

Continental Drift Theory

Early theory that continents moved slowly across Earth's surface.

Pangaea

A supercontinent that existed about 300 million years ago, comprising all major landmasses.

Panthalassa

The vast global ocean surrounding Pangaea.

Gondwana and Laurasia

Two landmasses that split from Pangaea to form the major continental pieces; precursor to the seven continents.

Contraction Theory

Idea that Earth cooled and its surface wrinkled into mountains.

Theory of Plate Tectonics

Theory that Earth's lithosphere is broken into moving plates.

Crust

The outermost solid shell of Earth.

Continental Crust

Thicker, less dense crust composed mainly of granitic rocks.

Oceanic Crust

Thinner, more dense crust composed mainly of basaltic rocks.

Silicon (Si)

A major element in the crust; one of the most abundant elements.

Oxygen (O)

The most abundant element in Earth's crust.

Aluminum (Al)

A common element in the crust; lightweight metal.

Calcium (Ca)

A crustal element; important in minerals.

Sodium (Na)

A crustal element; common in minerals.

Potassium (K)

A crustal element; common in minerals.

Mantle

The thick shell between the crust and core; hot, solid rock with convection.

Outer Core

Liquid iron-nickel layer about 2250 km thick; generates Earth's magnetic field.

Inner Core

Solid iron-nickel sphere about 1300 km in radius; extremely hot and under immense pressure.

Core

The Earth's center, consisting of the Outer Core and Inner Core.

Chondrite

A primitive stony meteorite considered a common material in the early solar system.

Mohorovicic Discontinuity (Moho)

The boundary between the crust and the mantle.

Gutenberg Discontinuity

The boundary between the mantle and the outer core.

Lehmann Discontinuity

The boundary between the outer core and the inner core.

Seismometers/Seismographs

Instruments used to detect and record seismic waves.

Body Waves

Seismic waves that travel through the interior of the Earth.