SCI121: L1 AND L2

50 vocabulary flashcards covering weathering, erosion, mass wasting, and key endogenous/exogenous geology concepts.

Weathering

The breakdown or dissolution of rocks and minerals at the Earth's surface, producing smaller pieces and altered minerals without transport.

Physical weathering

Mechanical breakdown of rocks into smaller pieces without changing their mineral composition.

Chemical weathering

Chemical alteration of minerals in rocks, changing their composition through reactions with water, acids, or bases.

Frost wedging

Water in cracks freezes, expands, and wedges rocks apart; fragments break off when ice melts.

Crystal growth

Salt or mineral crystals grow in rock pores when groundwater moves in and water evaporates, exerting pressure.

Abrasion

Wearing away of rocks by constant collision and impact of loose particles, rounding edges.

Biotic weathering

Weathering caused by living organisms, including plants, animals, and microbes.

Plant roots

Roots penetrate cracks, exert pressure, and wedge rocks apart.

Burrowing animals

Organisms like earthworms and termites break down rocks through burrowing.

Humans (anthropogenic effects)

Human activities (agriculture, construction, mining) contribute to rock breakdown and increased weathering.

Dissolution

Dissociation of minerals into ions; acids and bases dissolve minerals more effectively than water.

Oxidation

Chemical reaction with oxygen (often in water) producing oxides; iron oxidation creates rust.

Hematite

Iron oxide mineral formed by oxidation, typically reddish.

Limonite

Iron oxide mineral formed during oxidation in soils.

Hydrolysis

Reaction of minerals with water to form new minerals (e.g., feldspar to clay) and release ions.

Feldspar to clay

Hydrolysis of feldspar forming clay minerals and releasing ions like Na, K, Ca, Mg.

Bowen's reaction series

Order in which minerals crystallize from cooling magma; olivine forms first, quartz last and most resistant.

Olivine

Early-crystallizing mineral that is relatively least resistant to weathering.

Quartz

Late-crystallizing mineral that is highly resistant to weathering.

Joints

Natural fractures in rocks that allow weathering agents to penetrate.

Folds

Bends in rocks from deformation that influence weathering patterns and fracture.

Faults

Fractures along which rocks have moved, providing pathways for weathering agents.

Bedding planes

Surfaces between sedimentary rock layers that act as weathering channels.

Topography

Slope and landscape features influencing weathering rates (steep vs gentle slopes).

Time

Duration of exposure to weathering; longer exposure increases degree of weathering.

Mass wasting

Downslope movement of rock, soil, and regolith driven by gravity.

Gravity (driving force)

Primary force causing mass wasting, pulling material downslope.

Oversteepening

Slopes steeper than the angle of repose become unstable and fail.

Removal of vegetation

Loss of plant cover reduces cohesion and enhances instability and erosion.

Ground vibration

Seismic or anthropogenic vibrations that trigger movement of loose materials.

Rock falls

Free-fall movement of rocks from a cliff, forming talus at the base.

Debris falls

Rock falls including soil, regolith, and vegetation; mixed debris at cliff base.

Talus

Pile of rock fragments accumulated at the base of a cliff from disintegrations.

Landslides

Sudden fast movement of cohesive rock, soil, or regolith downslope.

Translational slides

Landslides where material moves along a well-defined surface (bedding/fault/joint).

Rotational slides

Landslides where material moves along a curved surface (slump).

Flows

Mass movements that involve fluids, including slurry or granular flows.

Slurry flows

Flows of rock or regolith with 20%–40% water; water-saturated.

Water-saturated flows

Flows with high water content contributing to rapid movement.

Erosion

Transport and removal of weathered sediments by agents of erosion; energy from the sun via the water cycle.

Splash erosion

Detachment of soil particles by raindrop impact.

Sheet erosion

Water runoff flows as a sheet, carrying soil downslope.

Gully erosion

Deep channels formed by concentrated runoff eroding soil.

Valley erosion

Erosion by continuous water flow along valleys, deepening them.

Coastline erosion

Waves erode coastlines, moving rocks to pebbles or sand and removing beach material.

Seaside cliff erosion

Wave action erodes cliffs, forming caves and arches that may collapse.

Glacier

Large, slow-moving ice mass that erodes land via plucking and abrasion.

Plucking

Glacial erosion where freezing water pulls rocks into the ice.

Wind erosion

Wind transports dust, sand, and ash, eroding or smoothing surfaces in dry areas.

Volcanism

Internal Earth process where extreme heat melts rocks into magma that may erupt as lava.

Metamorphism

Change in mineral assemblage and texture of rocks due to heat, pressure, and chemical environment.

Textural changes in metamorphism

Growth, disappearance, or rearrangement of minerals due to metamorphic conditions.

Foliation

Layered or sheet-like appearance in metamorphic rocks caused by aligned minerals under stress.

Non-foliated metamorphic rocks

Metamorphic rocks lacking foliation (e.g., marble, hornfels, quartzite) formed by heat/chemical change without differential stress.

Coal to diamond (metamorphic example)

Coal subjected to high pressure can transform into diamond due to metamorphic conditions.

Heat (in metamorphism)

One of the key drivers of metamorphism, causing mineral changes and recrystallization.

Pressure (in metamorphism)

Confining or differential pressure influencing mineral alignment and foliation.

Confining pressure

Uniform pressure that squeezes rocks evenly, often promoting compactness.

Differential pressure

Uneven pressure causing deformation and foliation in rocks.

Gravitational contraction/heat from gravity

Early Earth formation through core accretion, where gravity heated and melted materials.

Radioactive decay of elements

Decay of unstable isotopes (e.g., U-238, K-40) releasing heat inside Earth.

Partial melting

Melting of only some minerals in a rock due to differing melting points, forming magma.

Decompression melting

Melting caused by pressure decrease as mantle material rises.

Addition of volatiles

Introduction of volatile substances (e.g., water) lowering melting points and aiding melting.