Unit 4 Plate Tectonics

Flashcards covering key concepts from the Unit 4 Plate Tectonics lecture notes.

What are the two main components of Earth's core?

The inner core is solid, while the outer core is liquid.

What is the mantle composed of?

Three layers: the innermost portion contains molten rock (magma), the asthenosphere is semi-molten and flexible, and the solid upper mantle.

How thick is the lithosphere?

Approximately 100 km (60 miles) thick.

What was Alfred Wegener's hypothesis about continents?

He proposed that continents were once joined in a single landmass called 'Pangaea'.

What evidence suggests that continents have moved over time?

The shapes of the continents, fossil evidence, and geological formations.

What does the theory of plate tectonics state?

Earth's lithosphere is divided into plates that are in constant motion, creating features on land and in oceans.

What causes an earthquake?

A sudden movement of Earth's crust caused by the release of potential energy from moving tectonic plates.

How is the magnitude of an earthquake measured?

It is reported on the Richter scale.

What is a hot spot in geology?

A place where molten material from Earth's mantle reaches the lithosphere.

What are the three types of tectonic plate boundaries?

Divergent, convergent, and transform boundaries.

What occurs at divergent boundaries?

Tectonic plates move away from each other, and rising magma forms new oceanic crust.

What happens during subduction at convergent boundaries?

The heavier oceanic plate slides beneath the lighter continental plate.

What characterizes transform boundaries?

Tectonic plates move sideways past each other, creating faults.

What environmental impacts can earthquakes have?

They can lead to collapsed structures, fires, contaminated water supplies, and loss of life.

Where are 85 percent of active volcanoes located?

Along plate boundaries.

What is magma?

Molten material formed beneath Earth’s surface.

What is the main factor affecting the violence of a volcanic eruption?

The composition of magma, specifically the amount of silica.

What type of volcano is characterized by symmetrical cone shape and rapid cooling lava?

Cinder cone volcano.

What are composite volcanoes primarily composed of?

Alternating layers of ash and lava.

How can volcanic eruptions impact the environment?

They can cause floods, mudslides, and release gases that lead to acid rain.