Plate Tectonics, Boundaries, Stresses, and Faults – Lecture Review

These flashcards cover foundational concepts, terminology, mechanisms, and evidence related to continental drift, plate tectonics, boundary types, associated stresses, and resulting geologic features and events.

Who first fully developed the Continental Drift Theory in 1912?

Alfred Wegener.

What supercontinent did Wegener propose existed about 200 million years ago?

Pangaea.

What was the name of the vast ocean that surrounded Pangaea?

Panthalassa.

Which two large landmasses did Pangaea split into?

Gondwanaland (south) and Laurasia (north).

Which type of plate boundary is characterized by plates moving apart?

Divergent plate boundary.

Which type of plate boundary involves plates moving toward one another?

Convergent plate boundary.

Which plate boundary is marked by plates sliding horizontally past each other?

Transform fault boundary.

What stress is associated with divergent boundaries?

Tension (extension).

What stress is associated with convergent boundaries?

Compression.

What stress is associated with transform boundaries?

Shearing.

What kind of fault forms under tensional stress?

Normal fault.

What kind of fault results from compressional stress?

Reverse fault.

What kind of fault is produced by shearing stress?

Strike-slip fault.

What mid-ocean feature is created at divergent boundaries under the sea?

Mid-ocean ridge.

What geologic structure often forms on land at divergent boundaries?

Rift valley.

What is sea-floor spreading?

The creation of new oceanic crust as magma rises at divergent boundaries and pushes plates apart.

Which scientist proposed mantle convection as the driving force for plate motion?

Arthur Holmes.

Who coined the term "plate" in the context of plate tectonics?

Tuzo Wilson.

What is the primary driving mechanism of plate movement in the mantle?

Convection currents.

What is slab pull?

The force exerted by a subducting plate that drags the rest of the plate toward the trench.

Name the three main types of convergent boundaries.

Oceanic-continental, oceanic-oceanic, and continental-continental convergence.

What surface feature marks oceanic-continental convergence?

An ocean trench adjacent to a continental volcanic arc (e.g., the Andes).

What forms where two oceanic plates converge?

A trench and an island arc (e.g., the Marianas Trench and Islands).

What major mountain range formed from continental-continental collision?

The Himalayas.

Which famous transform fault lies in California?

The San Andreas Fault.

Where are most active volcanoes located globally?

Along the Pacific Ring of Fire.

What evidence from continental coastlines supports continental drift?

Jigsaw-fit matching of South America and Africa.

How do matching rock ages across oceans support drift?

Similar aged rock belts extend from one continent to another across present oceans.

What sedimentary rock made from glacial deposits supports the Gondwana connection?

Tillite.

Which tiny reptile’s fossils in Brazil and South Africa support continental drift?

Mesosaurus.

What are the rigid, moving segments of Earth’s lithosphere called?

Tectonic plates.

Which layer do plates "float" upon and move across?

The asthenosphere.

Name two plates that converge to form the Andes Mountains.

Nazca Plate and South American Plate.

What is the approximate motion rate of the Philippine Sea Plate?

About 54–102 mm per year toward the northwest.

Which process creates folded mountains without subduction?

Continental-continental collision causing crustal buckling.

What type of boundary neither creates nor destroys crust?

Transform boundary.

What is the boundary between Earth’s crust and mantle?

The Mohorovičić discontinuity (Moho).

Which plate is mostly responsible for earthquakes and volcanoes around the Pacific Ocean?

The Pacific Plate.

What global zone is the most seismically and volcanically active?

The Pacific Ring of Fire.

What is the principal cause of earthquakes at transform boundaries?

Accumulation and release of strain as plates slide past each other.

What geological feature results from sea-floor spreading over millions of years in the Atlantic?

The widening of the Atlantic Ocean along the Mid-Atlantic Ridge.

What fault type has rocks on either side sliding horizontally?

Strike-slip fault.

Which force did Wegener originally propose to drive continental drift but was later deemed insufficient?

Pole-fleeing force and tidal drag.

Give one criticism of Wegener’s original continental drift theory.

He lacked a convincing mechanism for moving large continents through rigid crust.

Define diastrophism.

The gradual deformation of Earth’s crust through folding, faulting, uplift, and subsidence.

What endogenic process creates mountains through intense lateral pressure?

Orogenic movements (mountain building).

Name one chemical weathering process important in rock decomposition.

Oxidation (or hydration, solution, carbonation—any one correct).

Which stress term describes rock being pulled or stretched?

Tension.

Which Philippine tectonic plate is oceanic and moves northwestward?

The Philippine Sea Plate.