PHS 102 Earth Science - Soil, Mass Wasting, Geology & Mineralogy Review

A complete deck of vocabulary flashcards covering soil horizon classifications, mass wasting phenomena, Earth spheres and layers, branches of earth science, mineral properties, mineral classes, and rock textures.

O Horizon

The top organic layer composed of loose, partly decayed organic matter.

A Horizon

The soil layer containing mineral matter mixed with organic matter and humus.

E Horizon

A light-colored mineral layer characterized by little organic matter and high eluviation and leaching.

B Horizon

The subsoil layer rich in humus, mineral deposits, metal salts, and weathered material.

C Horizon

The soil layer consisting of partially weathered parent rock.

R Horizon

The unweathered parent rock or solid bedrock underlying the soil profile.

Mass Wasting

The downslope movement of rock, regolith, and soil under the direct influence of gravity.

Solifluction

Slow downslope flow of water-saturated soil into tongue-shaped lobes, occurring in periglacial or arctic/alpine environments where the active top layer thaws in summer over an impermeable permafrost layer.

Soil Creep

The slow downslope movement of soil and regolith over decades caused by gravity and repeated freeze-thaw cycles, often evidenced by J-shaped upper tree trunks bending toward sunlight or bulging soil.

Rock Fall

Rapid free-fall of rock debris from a steep cliff or slope, often triggered by freeze-thaw weathering or earthquake shaking and leaving fallen boulders scattered at the cliff base.

Lahar

A rapid downslope flow consisting of a mixture of mud, snow, ice, and volcanic debris originating from volcanic craters that flows like wet concrete.

Slump

A type of mass wasting characterized by movement along a curved scarp at the top with a bench or step partway down the slope, often triggered by river undercutting or vegetation removal.

Landslide

Rapid movement of a large mass of rock, debris, or earth down a slope, leaving a detachment scar and forming a tongue-shaped deposit at the bottom.

Debris Flow

A rapid flow of a fast-moving mixture of water, rocks, and soil (mudflow) that carves channels into the landscape and leaves unsorted deposits.

Angle of Repose

The steepest angle at which a pile of loose granular material remains stable.

Crust

The thin, brittle, outermost layer of the Earth, composed of lighter rocks such as basalt in oceanic regions.

Mantle

A vast layer of hot, mostly solid rocks extending about $2,900\,\text{km}$ deep, composed of silicate minerals rich in magnesium and iron such as olivine, garnet, and pyroxene.

Outer Core

A steaming hot liquid layer composed of iron and nickel reaching temperatures of $5,700\,^\circ\text{C}$ and higher.

Inner Core

The solid center layer of the Earth made up of iron and nickel.

Asthenosphere

A layer located in the upper mantle below the rigid lithosphere.

Atmosphere

Earth's gaseous envelope composed of nitrogen and oxygen that regulates climate, protects from solar radiation, and supports life.

Biosphere

The sum of all living organisms on Earth, including plants, animals, and humans.

Hydrosphere

All water present on Earth, including oceans, lakes, rivers, glaciers, groundwater, and atmospheric moisture.

Geosphere

The solid rock outer shell of the Earth (lithosphere), including the crust, upper mantle, mountains, continents, and ocean floor.

Geology

The study of Earth's solid structures, rocks, minerals, and landforms.

Meteorology

The branch of science that studies weather patterns and atmospheric phenomena.

Climatology

The study of Earth's climate systems and long-term atmospheric patterns.

Oceanography

The study of ocean waves, tides, currents, and marine ecosystems.

Hydrology

The branch of science dealing with water resources, groundwater, rivers, and watersheds.

Environmental Science

The field that examines human impacts on ecosystems and strategies for sustainability.

Astronomy & Planetary Science

The study of the solar system, universe, space weather, asteroids, and celestial bodies.

Soil Science

The study that analyzes soil composition, fertility, and conservation.

Geophysics

The branch of earth science that investigates Earth's internal structure and surface using physical principles.

Age of Earth

The estimated age of the Earth, which is around $4.54\,\text{billion}$ years old.

Mineral

A naturally occurring, inorganic solid substance with a definite chemical composition and structure.

Luster

The quality and appearance of light reflected from the surface of a mineral.

Metallic Luster

An opaque, highly reflective mineral luster resembling metal, as seen in gold and silver.

Vitreous Luster

A glassy, shiny mineral luster seen in minerals such as quartz and feldspar.

Pearly Luster

A iridescent, pearl-like mineral luster seen in minerals like muscovite and stilbite.

Adamantine Luster

An exceptionally brilliant, diamond-like luster seen in minerals such as diamond and zircon.

Streak

The color of a mineral in its finely powdered form when rubbed against an unglazed porcelain plate.

Mohs Scale

A standard qualitative relative scale used to determine mineral hardness based on scratch resistance relative to reference minerals.

Cleavage

The tendency of a mineral to break along smooth, flat planes determined by weak atomic bonds in its crystal structure.

Fracture

The way a mineral breaks along curved, irregular, or rough surfaces that are not controlled by crystal cleavage planes.

Silicate Minerals

The most common mineral group on Earth, containing silicon, oxygen, and metal cations such as magnesium, iron, and aluminum.

Non-Silicate Minerals

Mineral groups that lack silicon-oxygen tetrahedra, including oxides, sulfides, sulfates, carbonates, halides, and native elements.

Hematite

An oxide mineral with a steel gray to black color and a distinctive reddish-brown streak.

Pyrite

A sulfide mineral with a brass-yellow color and a black streak.

Mica

A group of silicate minerals (such as muscovite and biotite) that exhibit perfect basal cleavage in only one direction.

Orthoclase Feldspar

A silicate mineral with a Mohs hardness of 5–6 that exhibits two directions of cleavage intersecting at $90^\circ$.

Halite

A halide mineral (rock salt) that displays three perfect directions of cleavage, forming cubic crystals.

Talc

A very soft mineral with a Mohs hardness of 1 to 2 that can easily be scratched by a fingernail.

Apatite

A mineral with a Mohs hardness of 5 that barely scratches glass.

Weathering

The physical breakdown and chemical alteration of rocks, soil, and minerals at or near Earth's surface through contact with the atmosphere, water, and biological organisms.

Erosion

The process by which earth materials are worn away and transported to other locations by natural forces such as water, wind, or ice.

Phaneritic Texture

A coarse-grained igneous rock texture where individual mineral grains are large enough to be identified without magnification, such as in granite.

Pegmatitic Texture

An igneous rock texture characterized by exceptionally large, coarse mineral grains.

Porphyritic Texture

An igneous rock texture featuring large individual crystals (phenocrysts) embedded in a fine-grained matrix, as in porphyritic andesite.

Aphanitic Texture

A fine-grained extrusive igneous rock texture where individual crystals are too small to see with the naked eye, such as in basalt.

Glassy Texture

An extrusive igneous rock texture produced by extremely rapid cooling that prevents crystal lattice formation, as seen in obsidian.

Vesicular Texture

An extrusive igneous rock texture containing spherical cavities created by trapped gas bubbles during cooling, as seen in pumice.

Detrital Sedimentary Rocks

Sedimentary rocks formed from accumulated solid fragments of weathered rock, such as sandstone and shale.

Chemical Sedimentary Rocks

Sedimentary rocks formed from material precipitated out of solution, such as limestone and rock salt.

Foliated Metamorphic Rocks

Metamorphic rocks displaying a parallel, layered, or banded alignment of mineral grains, such as slate and schist.

Non-Foliated Metamorphic Rocks

Metamorphic rocks that lack a layered or banded mineral alignment, such as marble and quartzite.