Earth's Interior, Earth's Layers, & Volcanoes

Midterm

What are Earth’s main interior layers?

Crust, Mantle, Outer Core, Inner Core.

What is the crust?

The thin, outermost layer of Earth; made of solid rock; includes continental and oceanic crust.

What is the mantle?

The thick layer beneath the crust; composed of hot, solid rock that can flow slowly.

What are the two parts of the core?

The outer core (liquid) and the inner core (solid).

What is the outer core made of and what is its state?

Liquid iron and nickel.

What is the inner core made of and what is its state?

Solid iron and nickel due to extreme pressure.

What causes convection in Earth’s mantle?

Heat from the core causes hot material to rise and cooler material to sink.

Why is mantle convection important?

It drives plate motion and contributes to volcanism and tectonic activity.

How do scientists know about Earth’s layers?

By studying seismic waves from earthquakes and how they change speed and direction.

What are P-waves and what do they tell us?

Seismic waves that travel through solids and liquids, showing where layers change.

What are S-waves and what do they tell us?

Seismic waves that travel only through solids, proving the outer core is liquid.

What is volcanism?

All processes related to the release of magma, hot fluids, and gases from Earth’s interior.

Why does magma rise toward Earth’s surface?

Magma is less dense than the surrounding rock.

What is magma called when it reaches the surface?

Lava.

At which plate boundaries are most volcanoes found?

Convergent and divergent plate boundaries.

What is a hot spot?

A stationary plume of hot mantle material that melts through the crust.

What forms when a hot spot is under continental crust?

Large volcanic regions or calderas (example: Yellowstone).

What forms when a hot spot is under oceanic crust?

Chains of volcanic islands (example: Hawaiian Islands).

How does volcanism differ at convergent boundaries?

Subduction causes melting, producing explosive volcanoes with thick magma.

How does volcanism differ at divergent boundaries?

Plates pull apart, magma rises easily, creating less explosive volcanoes and new crust.

Why are convergent volcanoes often more explosive than divergent ones?

The magma is thicker and traps gas, increasing pressure.