Chapter 3: Rocks and the Rock Cycle

Comprehensive vocabulary flashcards covering the rock cycle, formation, textures, compositions, and classifications of igneous, sedimentary, and metamorphic rocks.

Rock

Any solid mass of mineral or mineral-like matter occurring naturally as part of our planet.

Igneous Rock

Rock formed by the crystallization of molten magma or lava.

Sedimentary Rock

Rock formed from the weathered products of preexisting rocks that have been transported, deposited, compacted, and cemented.

Metamorphic Rock

Rock formed by the alteration of pre-existing rock deep within Earth by heat, pressure, and chemically active fluids.

The Rock Cycle

A continuous model that shows the interrelationships among the three rock types: igneous, sedimentary, and metamorphic.

Magma

Molten rock located deep beneath Earth's surface.

Lava

Molten rock that reaches Earth's surface.

Weathering

The process that breaks down rocks by water, air, and life into sediment.

Sediment

Weathered pieces of rock produced by weathering.

Deep Geothermal Heat (Rock Cycle Driver)

Heat energy from Earth's interior that drives internal processes responsible for forming both igneous and metamorphic rocks.

Solar Energy (Rock Cycle Driver)

Energy from the sun that powers external surface processes, including weathering and the movement of weathered materials, to produce sedimentary rocks.

Intrusive Igneous Rock

Rock formed when magma hardens beneath Earth's surface; slow cooling deep underground allows large, visible mineral crystals to grow.

Extrusive Igneous Rock

Rock formed when lava hardens on or near Earth's surface; rapid cooling at the surface results in small, fine-grained mineral crystals.

Coarse-Grained Texture

An igneous rock texture produced by slow cooling deep underground, allowing large, visible mineral crystals to grow (e.g., Granite).

Fine-Grained Texture

An igneous rock texture produced by rapid cooling at or near the surface, resulting in small, interconnected mineral grains (e.g., Rhyolite).

Glassy Texture

An igneous rock texture produced by very rapid cooling that prevents crystal growth entirely, creating smooth, reflective surfaces (e.g., Obsidian).

Porphyritic Texture

An igneous rock texture caused by different rates of cooling, resulting in minerals of varied sizes within the same rock.

Granitic Composition

Igneous rocks made mostly of light-colored silicate minerals such as quartz and feldspar; rich in silica and typically crystallizing slowly underground to form coarse textures.

Basaltic Composition

Igneous rocks made mostly of dark-colored silicate minerals and calcium-rich plagioclase feldspar.

Andesitic Composition

Igneous rocks with a mineral makeup intermediate between granitic light-colored minerals and basaltic dark-colored minerals.

Ultramafic Composition

Igneous rocks made mostly from iron- and magnesium-rich minerals (such as olivine and pyroxene), yielding very dark and dense characteristics.

Erosion

The geological process that involves the weathering and the removal of rock.

Deposition

The sedimentary process that occurs when an agent of erosion—water, wind, ice, or gravity—loses energy and drops sediments.

Compaction

A sedimentary process that squeezes, or compacts, sediments together under pressure.

Cementation

A sedimentary process that takes place when dissolved minerals are deposited in the tiny spaces among sediments.

Clastic Sedimentary Rocks

Sedimentary rocks composed of weathered bits of preexisting rocks and minerals, classified primarily by particle size.

Chemical Sedimentary Rocks

Sedimentary rocks that form when dissolved substances precipitate, or separate, from water.

Sedimentary Structures

Physical features found in sedimentary rocks—such as strata, fossils, ripple marks, and mud cracks—that provide clues indicating how, when, and where the rocks formed.

Metamorphism

A term meaning "to change form"; the process by which rocks are altered at elevated temperatures and pressures.

Contact Metamorphism

Metamorphism that occurs when magma moves into rock, driven primarily by a rapid rise in temperature near a massive, high-temperature body of underground magma.

Regional Metamorphism

Metamorphism resulting from directed pressures and high temperatures during mountain building, producing large-scale deformation, high-grade metamorphism, and the greatest volume of metamorphic rock.

Hydrothermal Solutions

Hot, water-based solutions escaping from a mass of magma that promote recrystallization by dissolving original minerals and depositing new ones.

Foliated Metamorphic Rock

A metamorphic rock that possesses a banded or layered appearance caused by directed pressure and mineral alignment.

Nonfoliated Metamorphic Rock

A metamorphic rock that does not have a banded or layered texture.