GEOL107 Cards

Core

The innermost layer of Earth, composed primarily of an iron-nickel alloy

Outer Core

The liquid layer of the core where extreme heat keeps the iron-nickel alloy melted, generating Earth's magnetic field

Inner Core

The solid center of Earth where extreme lithostatic pressure forces the iron-nickel alloy to remain solid despite temperature exceeding the melting point

Mantle

The thick, silicate-rock layer between the crust and core, composed mainly of peridotite rich in iron and magnesium.

Asthenosphere

The ductile, semi-fluid upper layer of the mantle that flows under high temperature and pressure, allowing tectonic plates to move above it

Lithosphere

The rigid, brittle outer shell of Earth consisting of the crust and upper mantle, broken into tectonic plates

Crust

The outermost solid silicate layer, categorized into thin, dense oceanic crust (basaltic) and thick, less-dense continental crust (granitic)

Plate tectonics

The unifying geological theory stating that Earth's lithosphere is divided into plates that move relative to each other over the asthenosphere driven by mantle convection

Continental Drift

The historical hypothesis proposed by Alfred Wegener stating that Earth's continents were once joined in a single supercontinent (Pangaea) and gradually drifted apart over geological time

Convergent Boundary

A tectonic boundary where two plates collide, resulting in subduction (one plate sliding beneath another) or continental collision to form mountain ranges

Divergent Boundary

A tectonic boundary where two plates pull apart, allowing magma to rise from the mantle and create new crust (e.g., mid-ocean ridges or rift valleys)

Transform Boundary

A tectonic boundary where plates slide horizontally past one another along strike-slip faults

Surficial Processes

Earth processes occurring at or near the surface driven primarily by solar energy, which powers the atmosphere, hydrosphere, and biosphere

Weathering

The physical breakdown and chemical alteration of rocks and minerals at or near Earth's surface

Physical Weathering

The mechanical breakdown of rocks into smaller fragments without altering their chemical composition (e.g., frost wedging, thermal expansion)

Chemical Weathering

The decomposition of rock minerals through chemical reactions with water, air, or acids to form new minerals and soluble ions (e.g., oxidation, hydrolysis, dissolution)

Erosion

The process by which moving water, ice, gravity, or wind loosen, pick up, and transport rock fragments and sediment

Deposition

The settling or dropping of transported sediment when the transporting agent (water, wind, or ice) loses kinetic energy and carrying capacity

Sediment

Loose solids produced by weathering and erosion, or precipitated directly from aqueous solutions

Rock Cycle

The continuous geological process by which rocks constantly transform between igneous, sedimentary, and metamorphic forms through melting, cooling, weathering, erosion, lithification, and metamorphism

Mineral

A naturally occurring, inorganic solid with a definite chemical composition and an ordered internal crystalline structure

Rock

A naturally occurring solid aggregate composed of one or more minerals, mineraloids, or organic materials

Isotope

Atoms of the same chemical element that have the same number of protons but different numbers of neutrons

Isotope Uses:

Geological tools used for radiometric dating to determine absolute rock ages, tracing geological processes, and analyzing paleo-climates via stable isotope ratios (e.g., Oxygen-18)

Silicates

The most common group of minerals in Earth's crust, constructed from silicon-oxygen tetrahedra

Feldspars

The single most abundant mineral group in Earth's crust, including plagioclase and alkali feldspar varieties

Quartz

A abundant crustal silicate mineral composed entirely of a framework of silicon dioxide

Ionic Bonding

Chemical bonding formed through the electrostatic attraction between oppositely charged ions created when one atom transfers valence electrons to another

Covalent Bonding

Chemical bonding formed when two or more atoms share valence electrons, creating strong chemical bonds (e.g., in diamond)

Metallic Bonding

Chemical bonding where valence electrons are shared freely among a lattice of metal cations in a sea of delocalized electrons, giving metals conductivity and malleability

Intermolecular (Van der Waals) Bonding

Weak electrostatic forces holding uncharged molecules or sheet layers together (e.g., between graphite layers)

Silicate Minerals

Minerals containing silicon and oxygen tetrahedral units, making up over 90% of Earth's crust (e.g., olivine, pyroxene, amphibole, mica, feldspar, quartz)

Carbonate Minerals

Minerals defined by the carbonate anion, such as calcite and dolomite

Oxide Minerals

Minerals composed of metallic cations bonded with oxygen ions such as hematite and magnetite

Sulfide Minerals

Minerals containing metallic cations bonded with sulfur anions, such as pyrite and galena

Sulfate Minerals

Minerals containing the sulfate complex, such as gypsum

Halide Minerals

Minerals containing halogen ions bonded with alkali metal ions, such as halite and fluorite

Native Elements

Minerals consisting of a single uncombined element, such as gold, copper, sulfur, and diamond

Mineral Color

The visual appearance of a mineral due to reflected light, which is often variable and unreliable for identification due to impurities

Streak

The color of a mineral in its powdered form, observed by rubbing the mineral across an unglazed porcelain plate

Luster

The way light reflects off the surface of a mineral, categorized broadly as metallic or non-metallic (e.g., vitreous, pearly, dull)

Hardness

A mineral's resistance to scratching, measured quantitatively on the Mohs Hardness Scale from 1 (talc) to 10 (diamond)

Cleavage

The tendency of a mineral to break along flat structural planes of weak chemical bonding

Fracture

The irregular or uneven breaking of a mineral in directions other than along cleavage planes (e.g., conchoidal fracture)

Specific Gravity

The ratio of the density of a mineral relative to the density of an equal volume of water at 4 celsius

Igneous Rock

Rock formed directly from the cooling and crystallization of molten rock (magma beneath the surface or lava at the surface)

Magma

Molten rock located beneath Earth's surface containing dissolved gases and suspended crystals

Lava

Molten rock that has breached Earth's surface

Parent Material

The original source rock whose melting produces magma, controlling the initial chemical composition of the melt (e.g., mantle peridotite vs. continental crust)

Partial Melting

The process where only a portion of a solid rock melts due to varying melting points of constituent minerals, yielding a magma richer in silica than the parent rock

Fractional Crystallization

The process where cooling magma precipitates minerals at different temperatures; as early-formed crystals drop out, the remaining liquid changes in chemical composition

Magmatic Differentiation

Any process (including fractional crystallization, magma mixing, and crustal assimilation) that alters the chemical composition of magma during cooling

Felsic Igneous Rock

Silica-rich igneous rocks containing high amounts of potassium and sodium, rich in quartz and feldspars, lighter in color, and derived mostly from continental crust (e.g., granite, rhyolite)

Mafic Igneous Rock

Silica-poor igneous rocks rich in iron and magnesium, dark in color, dense, and typical of oceanic crust (e.g., basalt, gabbro)

Intermediate Igneous Rock

Igneous rocks with composition between felsic and mafic, commonly associated with volcanic arc subduction zones (e.g., andesite, diorite)

Ultramafic Igneous Rock

Very low silica igneous rocks consisting almost entirely of olivine and pyroxene, representing Earth's mantle (e.g., peridotite, komatiite)

Phaneritic Texture

An igneous rock texture characterized by coarse, visible mineral grains produced by slow cooling deep underground (intrusive)

Aphanitic Texture

An igneous rock texture characterized by fine-grained crystals invisible to the naked eye due to rapid cooling at or near Earth's surface (extrusive)

Porphyritic Texture

An igneous rock texture containing large crystals (phenocrysts) embedded within a fine-grained matrix (groundmass), caused by two distinct stages of cooling

Viscosity

A fluid's resistance to flow; in magma, higher silica content and lower temperature lead to higher viscosity

Eruptive Violence

The explosive potential of a volcanic eruption, dictated by lava viscosity and gas content (high-silica felsic lavas trap gas and erupt explosively, while low-silica mafic lavas allow gas to escape and flow effusively)

Dissolved Gases in Magma

Volatiles contained within magma that dictate eruptive style based on their concentration and ease of escape

Viscosity

A fluid's resistance to flow; higher silica content and lower temperatures increase lava viscosity

Explosive Eruption

A violent volcanic eruption driven by viscous magma trapping expanding dissolved gases

Effusive Eruption

A non-explosive volcanic eruption characterized by fluid, low-viscosity lava flowing smoothly out of a vent

Pyroclastic Materials

Solid fragmental debris ejected during an explosive volcanic eruption, including dust, ash, cinders, lapilli, blocks, and bombs

Pyroclastic Flow

A high-density, rapidly moving avalanche of incandescent gas and pyroclastic debris flowing down a volcano's slope

Volcanic Activity at Divergent Boundaries

Volcanism driven by decompression melting as tectonic plates separate, producing effusive basaltic magmas, pillow lavas, mid-oceanic ridges, and features like Iceland

Decompression Melting

The process where mantle rock melts as it ascends toward the surface due to a reduction in confining pressure

Volcanic Activity at Convergent Boundaries

Volcanism occurring at subduction zones that forms composite volcanoes producing explosive eruptions and viscous, silica-rich andesitic lavas

Within-Plate Volcanic Activity

Volcanism occurring away from plate boundaries caused by stationary mantle plumes (hot spots), such as Hawaii and Yellowstone

Mantle Plumes (Hot Spots)

Columns of hot mantle material rising from deep within the Earth to generate intraplate volcanic activity