Physical Geology - Chapter 4: Igneous Rocks

These flashcards cover key terms and definitions related to igneous rocks as discussed in Chapter 4 of Physical Geology.

Igneous Rocks

Rocks formed from the cooling of molten material (magma or lava).

Magma

Molten material beneath the earth’s surface composed of liquid, solid rocks, and gases.

Lava

Molten rock material that rises to the earth’s surface during volcanoes.

Partial Melting

The process by which magma is formed within the earth’s crust and upper mantle.

Intrusive Igneous Rocks

Rocks formed when magma crystallizes at depth before reaching the surface.

Extrusive Igneous Rocks

Rocks formed when molten rock solidifies at the earth’s surface during volcanic eruptions.

Aphanitic Texture

Fine-grained texture resulting from rapid cooling of magma.

Phaneritic Texture

Coarse-grained texture resulting from slow cooling of magma.

Bowen’s Reaction Series

A diagram illustrating the sequence of minerals crystallization from magma as it cools.

Mafic Rocks

Igneous rocks composed of ferromagnesian minerals, rich in iron and magnesium.

Felsic Rocks

Igneous rocks composed mainly of potassium feldspar and quartz, lighter in color.

Tephra

Ash and lapilli that fall around a volcano, can bury landscapes and cause damage.

Pyroclastic Flows

Clouds of ash and gas that rapidly flow downslope, immediately lethal to living beings.

Volcanic Gases

Poisonous gases released from volcanoes, can be deadly, like in the Lake Nyos disaster.

Glassy Texture

Texture with no orderly crystal structure due to very rapid cooling of magma.