Plate Tectonics Study Questions

These flashcards cover key concepts and details from the Plate Tectonics lecture notes to aid in studying for the exam.

What did Alfred Wegner contribute to geology?

He proposed the theory of continental drift and provided evidence for the existence of Pangaea.

List one piece of evidence used by Wegner for Pangaea.

Fossil distributions across continents.

Why was Wegner’s theory initially rejected?

There was insufficient evidence and a lack of a mechanism for drift.

What process explains how continents move apart?

Seafloor spreading.

Define mid-ocean ridges.

Underwater mountain ranges formed by plate tectonics.

What is a subduction zone?

An area where one tectonic plate moves under another.

What do marine magnetic anomalies demonstrate?

Patterns of Earth's magnetic field reversal over time.

What happens to oceanic rocks as they move away from mid-ocean ridges?

They age and become cooler and denser.

What layers are identified in Earth's composition?

Core, mantle, and crust.

What is isostasy?

The equilibrium between Earth's crust and the underlying mantle.

What happens at divergent plate boundaries?

Plates move apart, leading to rift formation or new oceanic crust.

What is the significance of the asthenosphere in plate tectonics?

It allows the lithosphere to move over it due to its plasticity.

What is the defining feature of transform boundaries?

Plates slide past one another horizontally.

How does oceanic plate density affect subduction?

Denser oceanic plates subduct beneath less dense continental plates.

What is a hot spot?

A volcanic region thought to be fed by underlying mantle that is hot.

Provide an example of a hot spot in the U.S.

The Hawaiian Islands.

What constitutes the oceanic lithosphere?

A combination of the crust and the uppermost mantle.

How are the properties of continental and oceanic crust different?

Continental crust is thicker and less dense than oceanic crust.

What occurs during a magnetic reversal?

Earth's magnetic north and south poles switch places.

Why do older rocks exist farther from mid-ocean ridges?

New oceanic crust is formed at mid-ocean ridges, pushing older rocks away.