Continental Drift & Plate Tectonics Lecture

30 Question-and-Answer flashcards covering Alfred Wegener’s continental drift, evidence for drift, limitations, the evolution to plate tectonics, plate types, boundary types, driving mechanisms, and real-world examples such as the Himalayas, Mid-Atlantic Ridge, and San Andreas Fault.

Who proposed the Continental Drift Theory in 1912?

Alfred Wegener

What was the name of the supercontinent that existed about 200–300 million years ago?

Pangaea (or Pangea)

Which vast ancient ocean surrounded Pangaea?

Panthalassa

According to continental drift, what happened to Pangaea over time?

It split into smaller fragments that drifted apart to form today’s continents.

What line of evidence involves the matching shapes of continental coastlines?

Continental fit

Give one example of matching mountain chains that support continental drift.

The Appalachians in North America align with the Caledonides in Britain and Norway.

Name two extinct reptiles whose fossils are found on both Africa and South America, supporting drift.

Cynognathus and Mesosaurus

Which plant fossil found across multiple southern continents supports the drift theory?

Glossopteris

What dating technique correlates rock ages across continents?

Radiometric dating

Why was Wegener’s original drift theory criticized?

He could not satisfactorily explain the mechanism driving continental movement.

Which theory updated continental drift by identifying moving rigid segments of lithosphere?

Plate Tectonic Theory

What are tectonic plates?

Large, rigid pieces of Earth’s lithosphere that move over the asthenosphere.

How do continental plates compare with oceanic plates in thickness and density?

Continental plates are thicker and less dense; oceanic plates are thinner and denser.

What is the hot, semi-fluid mantle layer beneath the lithosphere called?

The asthenosphere

What is the main driver of plate motion beneath the asthenosphere?

Convection currents generated by heat from Earth’s core

Name the three basic types of plate boundaries.

Convergent, divergent, and transform

At which boundary do plates move toward each other, often forming mountains or subduction zones?

Convergent boundary

What geological feature is created at divergent boundaries on the ocean floor?

Mid-ocean ridges where new crust forms

Which boundary involves plates sliding past each other horizontally, producing earthquakes?

Transform boundary

Give the classic example of a continental-continental convergent boundary that formed very high mountains.

The collision of the Indian and Eurasian plates forming the Himalayas

Which mid-ocean ridge is an example of a divergent plate boundary between the North American and Eurasian plates?

The Mid-Atlantic Ridge

Name the famous transform fault separating the Pacific and North American plates in California.

San Andreas Fault

What term describes the downward pull of a dense, cooling oceanic plate at a subduction zone?

Slab pull

What term describes the force of rising magma at mid-ocean ridges pushing plates apart?

Ridge push

What radioactive process supplies much of the heat that drives mantle convection?

Decay of radioactive elements in Earth’s core

What are convection cells in the mantle?

Circular patterns of mantle flow that transfer heat and move lithospheric plates

How does the plate tectonics concept summarize Earth’s crustal dynamics?

It states that Earth’s lithosphere is divided into moving plates whose interactions shape geological features.

Which plate boundary type typically produces the strongest, deepest earthquakes?

Convergent (especially at subduction zones)

What evidence shows that Western Africa once connected to Eastern South America?

A 2-billion-year-old band of ancient rocks on both margins matched by radiometric dating

What overall lesson does the lecture emphasize about Earth’s surface?

Earth’s plates are constantly shifting, reshaping continents, oceans, and landforms.