EMES101 Study Guide: Volcanoes

These flashcards help review key concepts about volcanoes, igneous rocks, eruption styles, and volcanic hazards.

What are igneous rocks classified by?

Igneous rocks are classified based on their texture and mineral composition.

What two criteria determine how igneous rocks are classified?

Mineral composition and texture.

What are the three primary textures of igneous rocks?

Glassy, phaneritic, and aphanitic.

How does volcanic glass form?

Volcanic glass forms when lava cools rapidly and solidifies without crystallizing.

What is a porphyritic texture?

A texture with large crystals embedded in a finer-grained matrix, often formed through two stages of cooling.

What type of igneous rock is porphyry classified as?

Porphyry is classified as an intermediate igneous rock.

What are the two most common elements in Earth’s crust?

Silicon and oxygen.

How does color indicate silica content in igneous rocks?

Generally, lighter-colored rocks have higher silica content.

What are the two main factors that determine explosivity in volcanoes?

Composition and gas content.

What is the difference between viscous and non-viscous fluids?

Viscous fluids resist flow, while non-viscous fluids flow easily.

What is pyroclastic debris?

Fragmental material ejected during a volcanic eruption, including ash and larger volcanic rocks.

What constitutes a lahar?

A volcanic mudflow, consisting of water mixed with volcanic debris.

What are the three most abundant volcanic gases?

Water vapor, carbon dioxide, and sulfur dioxide.

Can you name different types of volcanic cones?

Shield volcanoes, stratovolcanoes, and cinder cones.

What is a lava dome?

A mound-shaped volcanic feature formed from the slow extrusion of viscous lava.

How does a caldera differ from a crater?

A caldera is a large depression formed from the collapse of a volcano, while a crater is a smaller depression at the summit.

What is a pyroclastic flow?

A fast-moving current of hot gas and volcanic matter that flows down the side of a volcano.

Why is Mt. Rainier considered dangerous?

Mt. Rainier poses risks due to its potential for lahars and its proximity to populated areas.

What hazards does volcanic ash pose?

Volcanic ash can cause respiratory problems, disrupt air travel, and contaminate water supplies.

What are bombs and blocks in volcanism?

Bombs are ejected molten rocks that solidify in the air, while blocks are larger pieces of solid rock ejected during an eruption.