Geology: Minerals, Rocks, Volcanoes, and Metamorphism Vocabulary

Vocabulary flashcards generated from geology lecture notes covering rocks, minerals, weathering, erosion, sedimentary features, volcanic activity, and metamorphic rocks.

Geology

The branch of science that deals with the surface and interior of Earth.

Mineral

A naturally occurring, inorganic solid with a specific internal crystalline structure and a definite chemical composition.

Rock

A naturally occurring solid mass or aggregate composed of one or more minerals, volcanic glass, or organic matter.

Magma

Molten rock located completely beneath Earth's surface.

Lava

Molten rock that has breached or extruded onto Earth's surface.

Intrusive Igneous Rock

A plutonic rock formed when molten magma solidifies slowly deep underground, usually producing coarse-grained crystals.

Extrusive Igneous Rock

A volcanic rock formed when molten lava solidifies rapidly above Earth's surface, usually producing fine-grained or glassy textures.

Felsic Magma

Magma rich in silica ($\text{SiO}_2$), aluminum, and potassium, characterized by high viscosity and high trapped gas content, leading to explosive eruptions.

Mafic Magma

Magma low in silica but rich in iron ($\text{Fe}$) and magnesium ($\text{Mg}$), characterized by low viscosity, leading to effusive eruptions.

Bowen's Reaction Series

A predictable sequence in which minerals crystallize from cooling magma or lava based on changing temperatures.

Shield Volcano

A large, broad, and slightly dome-shaped volcano built by successive layers of low-viscosity basaltic lava.

Cinder Cone Volcano

A small, steep-sided volcanic cone built entirely from ejected, loose lava fragments that solidify while in flight.

Composite Volcano (Stratovolcano)

A large, symmetrical cone composed of alternating layers of explosive ash/pyroclastics and effusive lava flows.

Large Igneous Province (LIP)

An immense accumulation of igneous rocks covering thousands of square kilometers, formed by prolonged deep-fissure eruptions of flood basalts.

Pillow Basalts

Basaltic lava structures most likely found near submarine volcanoes where lava extrudes directly underwater.

Pyroclastic Flow

A lethal, fast-moving, superheated avalanche of gas, ash, pumice, and rock fragments that races down a volcanic slope during an explosive eruption.

Lahar

A destructive volcanic mudflow generated when volcanic debris mixes with water, which can be triggered by active or inactive volcanoes.

Weathering

Processes that physically or chemically break down rocks at or near Earth's surface without transporting them.

Frost Wedging

A physical weathering process where water fills rock fractures, expands by roughly $9\%$ upon freezing, and exerts pressure to shatter the rock.

Sheeting

A physical weathering process where large masses of igneous rock expand upward when overlying weight is removed, causing outer layers to fracture and peel off.

Differential Weathering

The process where softer or more fractured materials weather faster and resistant materials weather slower.

Regolith

The layer of rock and mineral fragments produced by weathering that covers bedrock.

Soil

A complex combination of mineral grains, organic matter, water, and gases.

Erosion

The physical removal and transport of stationary rock or sediment material by natural processes such as wind, water, glaciers, or gravity.

Paleosol

An ancient soil preserved within the geologic record.

Lithification

The process of converting loose clastic sediments into solid sedimentary rock through burial, compaction, and cementation.

Sandstone

A detrital/clastic sedimentary rock with a grain size of approximately $1\,\text{mm}$.

Chert

A chemical sedimentary rock made mostly of silica that precipitated directly from water.

Metamorphism

The process of subjecting a pre-existing parent rock to intense heat, pressure, and chemically active hydrothermal fluids without complete melting.

Protolith

The original, pre-existing parent rock before it underwent metamorphism.

Foliation

A planar or layered alignment of platy or elongated minerals caused by directional, differential stress during metamorphism.

Slate

A low-grade, foliated metamorphic rock commonly produced by the metamorphism of shale.

Gneiss

A high-grade metamorphic rock exhibiting distinct compositional banding of light and dark minerals, typically formed from metamorphosed granite.

Marble

A non-foliated metamorphic rock composed primarily of calcium carbonate ($\text{CaCO}_3$), formed by the metamorphism of limestone.