Volcanoes and Igneous Rocks

These flashcards cover key vocabulary and concepts related to volcanoes and igneous rocks discussed in the lecture.

Intrusive Rocks

Rocks formed from magma that cools and solidifies beneath the Earth's surface.

Extrusive Rocks

Rocks that are formed from lava that cools and solidifies on the Earth's surface.

Mafic

Igneous rocks that are rich in magnesium and iron, often dark in color.

Felsic

Igneous rocks that are high in silicon and aluminum, typically lighter in color.

Bowen's Reaction Series

A sequence that illustrates the order in which minerals crystallize from cooling magma.

Porphyritic

A texture of igneous rocks characterized by large crystals embedded in a finer-grained matrix.

Silica and Explosivity

Higher silica content in magma generally increases explosivity.

Shield Volcano

A broad, gently sloping volcano built from lava flows, typically non-explosive.

Composite Cone Volcano

A volcano characterized by alternating layers of lava flow and explosive ash, forming a steep profile.

Pahoehoe vs. Aa

Pahoehoe is a smooth, ropy lava flow; Aa is a rough, jagged lava flow.

Caldera

A large depression formed after an explosive volcanic eruption.

Tephra

Any volcanic material ejected into the air during an eruption, including ash, pumice, and larger fragments.

Pyroclastic Flow

A fast-moving current of hot gas and volcanic matter that moves away from a volcano during an explosive eruption.

Lithic Tuff

A type of volcanic rock formed from the consolidation of volcanic ash and stones.

Volcanic Dome

A mound-shaped volcano formed by the slow extrusion of viscous lava.

Lahar

A destructive mudflow on the slopes of a volcano, formed from ash and debris mixing with water.

Rhyolite

An extrusive igneous rock that is high in silica and often associated with explosive volcanism.