Exam 4 (current unit)

What is weathering?

The combined set of natural processes that break down rock at or near Earth’s surface without transporting it elsewhere.

What are the two major pathways of weathering?

Physical and Chemical Weathering, involving mechanical disintegration and alteration of mineral composition, respectively.

What does 'in situ' mean in weathering context?

A condition where rock or material remains in its original location while undergoing change.

What is regolith?

A loose layer of fragmented material that overlies solid bedrock and may eventually contribute to soil formation.

What determines the internal resistance of material?

The ability of a rock or mineral to withstand breakdown based on properties like hardness and composition.

How does mineralogy affect weathering?

The specific mineral makeup of a rock strongly influences how quickly it decomposes.

What are areas of weakness in rocks?

Structural flaws such as fractures or joints that allow weathering processes to act more efficiently.

How does climate influence weathering?

Climate is a major control on weathering intensity through variations in moisture and temperature.

What is aspect in relation to weathering?

The directional orientation of a slope that affects sunlight exposure and environmental conditions.

What is crystallization in weathering?

A mechanical weathering process where growing mineral crystals exert pressure on surrounding rock.

What is ice wedging?

The expansion of freezing water within cracks that forces rock apart over repeated cycles.

How does salt weathering occur?

The breakdown of rock caused by salt crystal growth in pore spaces or fractures.

What is talus?

Accumulations of angular rock fragments commonly found at the base of steep slopes or cliffs.

What is the effect of wetting and drying on rocks?

A process that weakens rock through repeated moisture absorption and evaporation cycles.

What is exfoliation in geological terms?

The peeling or shedding of outer rock layers caused by pressure release or thermal expansion.

What does thermal expansion lead to in weathering?

The stress produced when materials repeatedly expand and contract due to temperature fluctuations.

What is biological weathering?

Rock breakdown caused by living organisms interacting physically or chemically with Earth materials.

What is chemical weathering?

The decomposition or alteration of minerals through chemical reactions involving water and gases.

How does acidity influence chemical weathering?

The influence of hydrogen ions in accelerating mineral dissolution and chemical reactions.

What is carbonate weathering?

A process especially effective on calcite-rich rocks where acidic water dissolves carbonate minerals.

What is limestone's susceptibility to weathering?

A sedimentary rock highly susceptible to dissolution, often showing pits, grooves, or etched surfaces.

What occurs during oxidation weathering?

A chemical reaction involving oxygen that commonly alters iron-bearing minerals into rust-like compounds.

What is hydrolysis?

A chemical weathering reaction where minerals react with water and transform into new substances such as clays.

What is differential weathering?

The uneven breakdown of rocks because some minerals resist weathering better than others.

What is the characteristic of quartz regarding weathering?

Quartz is a highly resistant mineral that commonly survives weathering and contributes heavily to sand deposits.

How do carbonates behave in weathering processes?

Carbonates weather relatively quickly when exposed to weak acids in water.

What is soil in a geological context?

A dynamic natural body composed of minerals, organic matter, air, and water capable of supporting plant life.

What is soil texture?

The relative proportion of differently sized mineral particles within soil.

What are the characteristics of sand as a soil particle?

Sand is the coarsest common soil particle size, promoting drainage but limiting water retention.

What defines silt in soil classification?

A medium-sized soil particle that feels smooth and retains more moisture than sand.

What is clay known for in soil properties?

Clay is the finest soil particle size, known for high water retention and shrink-swell behavior.

What is soil structure?

The arrangement of soil particles into aggregates that influence water and air movement.

What is a granular structure in soil?

A soil arrangement commonly associated with productive surface horizons and high biological activity.

What does blocky structure refer to in soil?

A roughly cube-shaped arrangement of soil aggregates often found in subsurface horizons.

What is prismatic structure in soil?

A vertically elongated soil arrangement that can influence drainage and root penetration.

How does soil color vary?

Soil color is influenced by moisture, organic content, and mineral composition.

What is organic matter in soil?

Decayed biological material that contributes nutrients and darker coloration to soils.

What are soil horizons?

Distinct layers within soil profiles formed through long-term environmental processes.

What is the O Horizon?

The organic-rich surface layer dominated by decomposing plant material.

What characterizes the A Horizon?

A mineral-rich topsoil layer mixed with organic matter and intense biological activity.

What is the E Horizon known for?

A light-colored layer where materials have been heavily leached downward.

What is the B Horizon?

A subsurface zone where materials such as clay or iron commonly accumulate.

What does the C Horizon represent?

A partially weathered parent material layer with limited biological alteration.

What does CLORPT stand for?

The five primary factors (Climate, Organisms, Relief, Parent Material, Time) that govern long-term soil formation processes.

How does climate affect soil formation?

Climate is the soil-forming factor that controls temperature and precipitation influences over time.

What role do organisms play in soil formation?

Organisms modify soil properties through the involvement of plants, animals, and microbes.

How does relief influence soil development?

Relief influences soil development and erosion based on topography and slope position.

What is parent material in soil?

The original geologic substance from which a soil develops.

How does time affect soil formation?

The duration over which soil-forming processes have acted on parent material.

What is soil degradation?

The decline of soil quality caused by erosion, nutrient loss, or other damaging processes.

What defines Alfisol?

A relatively fertile forest-associated soil order common in temperate climates.

What characterizes Mollisol?

A dark, organic-rich soil order typically associated with grassland ecosystems.

What is infiltration in soil?

The downward entry of water from the surface into soil.

What is percolation?

The continued movement of infiltrated water through pore spaces below the surface.

What is porosity in geological terms?

The proportion of open space within soil or rock capable of holding water or air.

What is permeability?

The ability of a material to transmit water through connected openings.

What is an aquifer?

A subsurface layer capable of storing and transmitting significant quantities of groundwater.

What is an aquitard?

A layer with low permeability that restricts groundwater movement.

What is surface runoff?

Water flowing across land when infiltration capacity is exceeded.

What is overland flow?

The movement of excess water downslope before entering stream channels.

What are rills?

Small channels carved into soil by concentrated runoff.

What are gullies?

Larger erosional channels formed when runoff becomes highly concentrated.

What is a drainage basin?

The total land area contributing water to a common stream system.

What is a drainage network?

The interconnected arrangement of streams within a basin.

What is stream discharge?

The volume of water moving through a stream channel over time.

What describes stream flow?

The movement characteristics of water traveling within a channel.

What is sediment load?

The total material transported by a river system.

What is bed load?

Sediment transported along the stream bottom through rolling or bouncing.

What is suspended load?

Fine particles carried within the water column by turbulence.

What is dissolved load?

Ions transported in solution rather than as solid particles.

What are channel forms?

The shapes and patterns developed by river channels under varying flow conditions.

What is aggradation?

The buildup of sediment causing a river channel or floodplain to rise.

What does incision refer to in river systems?

The deepening of a river channel through erosion into underlying material.

What is a floodplain?

A broad flat area adjacent to rivers that experiences periodic flooding.

What are meanders in a stream?

Sinuous bends in a stream channel produced by lateral erosion and deposition.

What are cut banks?

The eroding outer edges of meander bends where flow velocity is greatest.

What are point bars?

Depositional features formed on the inner bends of meanders.

What are oxbow lakes?

Isolated water bodies formed when meander loops are cut off from the main channel.

What are meander scars?

Remnant surface marks indicating former stream channel positions.

What are natural levees?

Raised ridges of sediment deposited alongside channels during floods.

What is sediment yield?

The total amount of eroded material delivered from a drainage basin.

What is sediment transport capacity?

The maximum quantity of sediment a stream can carry under specific flow conditions.

What are terraces in a geological context?

Step-like benches along valleys representing former floodplain levels.

What is dendritic drainage?

A branching stream pattern resembling tree limbs, usually forming on uniform material.

What is deranged drainage?

A poorly integrated drainage pattern often associated with recently glaciated terrain.

How do humans interact with rivers and floods?

Human activity and natural river systems can interact to intensify flood impacts.