G10 Science - Plate Tectonics: Key Concepts and Evidence

Flashcards covering plate tectonics concepts, evidence, boundaries, processes, and key figures drawn from the lecture notes.

Who is considered the primary proponent of the theory of plate tectonics and continental drift?

Alfred Wegener.

What is the theory that continents were once joined in a single landmass and have drifted apart?

Continental drift (the idea that continents were once connected in a supercontinent called Pangaea and have moved apart).

What is the name of the supercontinent Wegener proposed?

Pangaea.

Name the seven major tectonic plates.

Pacific, North American, South American, Eurasian, African, Antarctic, and Indo-Australian plates.

What two main parts make up the Earth's lithosphere?

The crust and the upper mantle.

What are the three main types of plate boundaries?

Convergent, Divergent, and Transform boundaries.

What happens at an oceanic-continental convergent boundary?

The denser oceanic plate subducts beneath the continental plate, forming a subduction zone and trench, with earthquakes and volcanic activity.

What happens at an oceanic-ocean convergent boundary?

One oceanic plate subducts beneath the other, forming deep trenches and volcanic island arcs.

What happens at a continental-continental convergent boundary?

Continental crust collides and buckles upward to form mountain ranges; subduction is limited.

What is a transform boundary?

A boundary where two plates slide past one another; crust is neither created nor destroyed; earthquakes occur.

What region around the Pacific is known for widespread volcanism and earthquakes due to subduction?

The Ring of Fire.

What is a volcanic hotspot?

A mantle plume that rises heat, creating magma and volcanoes as a plate moves over it.

What causes plate motion according to the mantle convection theory?

Convection currents in the mantle—hot material rises, cools, sinks—driving plate movement.

What is paleomagnetism?

The study of the Earth's past magnetic field as recorded in rocks, including reversals, used to infer plate motion.

How is paleomagnetism used to estimate plate movement over geologic time?

By dating magnetic reversals and measuring rock magnetization to determine average movement rates.

What information do seismic waves provide in earthquake analysis?

Location and type of fault movement; focal mechanisms indicate direction of plate movement.

What are VLBI and SLR used for in plate tectonics?

VLBI determines precise Earth positions using distant quasars; SLR measures distances to satellites with lasers to track motion.

What is the role of computer modeling in plate tectonics?

To simulate plate movement and test hypotheses about driving forces.

Name fossil clues that support continental drift.

Similar fossils found on now-distant continents, e.g., Lystrosaurus, Cynognathus, Mesosaurus, Glossopteris.

What climate clues support continental drift?

Evidence of glaciers in areas that are now tropical, indicating colder past climates.

What rock clues support continental drift?

Matching rock structures and formations on continents that are now far apart (e.g., eastern US and western Europe).

What does the distribution of Glossopteris across Gondwanaland indicate?

That southern continents were once connected.

What are tectonic plates primarily composed of?

Rigid lithosphere consisting of the crust and upper mantle.

What boundary is associated with the Mid-Atlantic Ridge?

Divergent boundary between oceanic plates forming new ocean floor.

What happens when continental crust diverges?

Rift valleys form, magma rises to create new ocean crust, potentially creating an ocean.

What is subduction?

One plate sinks beneath another into the mantle at a subduction zone.

What is a trench?

A deep elongated depression formed at subduction zones.

What is a volcanic arc?

A curved chain of volcanoes formed above a subducting plate.

What transform boundary example is well-known in California?

The San Andreas Fault, where the Pacific and North American plates slide past each other.

Where is the Mariana Trench and what boundary does it illustrate?

In the western Pacific; a subduction zone where the Pacific Plate subducts beneath the Philippine Plate (Philippine Sea Plate).

What happens at convergent boundaries in terms of geological features?

Trenches, mountains, earthquakes, and volcanic activity.

What evidence supports plate tectonics besides direct movement measurements?

Fossil distribution, ancient climate indicators, and correlated rock formations across continents.

What is the role of hotspots like Hawaii and Yellowstone in plate tectonics evidence?

Volcanic chains form as plates move over relatively fixed hotspots, indicating plate motion.