Physical Geography Final

Albedo

Reflectivity of a surface; determines how much incoming solar energy is reflected back to space.

Anticyclone

A high-pressure system with descending, diverging air. Produces clear, stable weather and clockwise circulation in the Northern Hemisphere.

Aquifer

A permeable rock or sediment layer that stores and transmits groundwater; forms the saturated zone beneath the water table.

Arroyo

A steep-walled, normally dry desert channel that briefly carries water during intense storms; associated with flash flooding.

Basalt

A dark, fine-grained mafic volcanic rock forming oceanic crust, lava plateaus, and hotspot flows.

Beach drift

The zig-zag movement of sediment along the beach caused by angled waves; part of longshore transport.

Caldera

A large volcanic depression formed when magma withdrawal or eruption causes the summit to collapse.

Carbonic acid

A weak acid formed when CO₂ dissolves in water; major agent of chemical weathering, especially in limestone.

CEC (Cation Exchange Capacity)

A measure of soil's ability to retain and exchange nutrient ions; influenced by clay and organic matter content.

Climograph

A graphical summary of monthly temperature and precipitation used to distinguish climate regimes.

Continental ice sheet

A massive ice body covering large areas and flowing outward in all directions; key agents of glacial erosion and deposition.

Creep

Very slow downslope soil movement caused by gravity, freeze-thaw, or moisture changes; detected by tilted trees and structures.

Deflation

Wind removal of fine sediment in deserts, forming deflation hollows and contributing to desert pavement.

Delta

Depositional landform at a river mouth where sediment accumulates as flow enters standing water.

Dewpoint

Temperature at which air becomes saturated and condensation begins.

Drumlin

Streamlined hill of till formed beneath a moving ice sheet; tapered end indicates ice-flow direction.

Ecotone

A transition zone between ecological communities, often high in species diversity.

Esker

A long, sinuous ridge of meltwater-deposited sand and gravel formed beneath glacial ice.

Equilibrium line

Boundary between a glacier's accumulation and ablation zones.

Ephemeral stream

A dry channel that carries water only after rainfall events.

Exfoliation

Mechanical weathering in which rock sheets peel off due to pressure release or thermal expansion.

Exotic stream

A river originating in a humid area but flowing through a dry one while maintaining perennial discharge.

Felsic

Silica-rich magma/rock (e.g., granite, rhyolite). Associated with explosive eruptions.

Flash flooding

Sudden, dangerous flooding in confined desert channels after intense rainfall.

Floodplain

Broad valley floor built by river deposition during overbank flooding and lateral channel migration.

Glaciation

Long-term growth and movement of glaciers that reshape landscapes through erosion and deposition.

Hadley cell

A tropical atmospheric circulation cell driven by equatorial heating, producing rising air, upper-level flow, and subsidence at ~30° latitude.

Hotspot track

A chain of progressively older volcanic features formed as a plate moves over a mantle hotspot.

Humus

Dark, stable organic material in soil that enhances nutrient retention and structure.

Hydrolysis

Chemical weathering process in which minerals react with water, forming clays and altering rock.

Hydrothermal system

Circulating hot groundwater near magma sources, producing geysers, hot springs, and steam vents.

Igneous

Rock formed by solidified magma or lava.

Infiltration

Water entering the soil; controlled by texture, vegetation, slope, and soil moisture.

Inselberg

Isolated rocky hill in a desert landscape formed by long-term erosion.

Interglacial

Warm interval between glacial advances; the Holocene is one example.

Interior drainage

Drainage in closed desert basins where rivers do not reach the ocean.

Isobar

Line of equal pressure on a weather map, used to infer wind patterns.

Isostatic rebound

Crustal uplift following removal of glacial ice.

ITCZ

Equatorial zone of rising air and thunderstorms where trade winds converge.

Karst

Landscape resulting from dissolution of limestone, producing caves, sinkholes, and disappearing streams.

Kettle lake

Small lake formed by melting of buried ice blocks left in glacial deposits.

Laccolith

A dome-shaped intrusive igneous body that arches overlying rock layers.

Loam

Balanced mixture of sand, silt, and clay; ideal for plant growth.

Loess

Wind-blown silt deposited during glacial periods; forms fertile soils.

Longshore current

A current running parallel to shore, created by angled waves; transports sediment.

Mass wasting

Gravity-driven downslope movement of soil and rock.

Mechanical weathering

Physical breakdown of rock without chemical alteration.

Meander

Sinuous river curve formed by lateral erosion and deposition.

Milankovitch cycles

Orbital variations (eccentricity, obliquity, precession) influencing long-term climate.

Monsoon

Seasonal wind reversal producing distinct wet and dry seasons.

Naturalized

Describes species that are nonnative but self-sustaining in a new environment.

Normal fault

Fault caused by crustal extension, with the hanging wall moving downward.

Overdeepened basin

Glacially carved valley floor eroded below its outlet, often forming lakes.

Oxidation

Chemical weathering involving reaction with oxygen, producing iron oxides.

Parent material

Original geologic or organic material from which soil develops.

PGF (Pressure Gradient Force)

Force that initiates wind by moving air from high to low pressure.

Playas

Flat desert basins that temporarily hold water after storms.

Pleistocene

Epoch marked by repeated glaciations over the past 2.6 million years.

Porosity

Percentage of pore space in rock or sediment.

Residual

Describes soils formed directly from underlying bedrock.

Reverse fault

Fault formed by compressional stress with hanging wall moving upward.

Rhyolite

Light-colored felsic volcanic rock associated with explosive eruptions.

Roche moutonnée

Asymmetric glacial erosion landform with smooth stoss and plucked lee sides.

Saturation

Air holding the maximum possible water vapor at a given temperature.

Scattering

Deflection of solar radiation by atmospheric particles; explains sky color.

Solutional weathering

Chemical dissolution of minerals, especially carbonates.

Submergent coastline

Coastline drowned by rising sea level, forming estuaries and flooded valleys.

Subtropical highs

Large high-pressure systems near 30° latitude, associated with deserts.

Tension

Tectonic stress that pulls the crust apart, forming normal faults.

Terminal moraine

Ridge of glacial till marking the furthest advance of a glacier.

Theory

A well-supported scientific explanation based on evidence.

Tide

Regular rise and fall of sea level from gravitational forces of Moon and Sun.

Tombolo

Sand or gravel bar connecting mainland to an offshore island.

Transpiration

Plant release of water vapor to the atmosphere.

Vertisol

Clay-rich soil that swells when wet and shrinks when dry, forming deep cracks.

Water table

Surface separating saturated and unsaturated ground zones.

Wave refraction

Bending of waves as they approach shallow water, focusing energy on headlands.

Weathering

Breakdown of rocks through physical and chemical processes.

Carbonic acid formation

Carbonic acid forms when CO₂ dissolves in water (H₂O + CO₂ → H₂CO₃) and its weak acidity reacts with calcium carbonate to dissolve limestone.

Conditions for karst development

Karst develops where soluble carbonate rocks (limestone/dolomite) exist, climates provide sufficient precipitation and CO₂, and fluctuating water tables and focused groundwater flow enable dissolution.

Formation of caves and sinkholes

Concentrated dissolution along fractures enlarges conduits to form caves, roof collapse creates sinkholes, and enlarged conduits route surface water into subsurface drainage.

Groundwater flow in karst landscapes

Groundwater preferentially enlarges fractures and conduits, concentrating flow paths and progressively reorganizing surface drainage into underground channels and collapse features.

Karst hazards in developed areas

Karst poses hazards like sudden sinkhole collapse, unpredictable foundation failure, and rapid pollutant transport through subsurface conduits.

Solutional vs hydrothermal processes

Solutional (karst) processes use cool, often CO₂-rich water dissolving rock near the surface, while hydrothermal processes involve hot, often metal-bearing fluids that dissolve and precipitate minerals at depth.

Groundwater heating

Groundwater heats when it circulates deep enough to encounter the geothermal gradient or magmatic heat, gaining temperature with depth and residence time.

Conditions for hot springs and geysers

Hot springs, geysers, and fumaroles require a heat source (magma or hot rock), permeable pathways for fluid, and in geysers specifically, water supply plus constricted plumbing to build pressure.

Geysers and confined pathways

Constrictions trap superheated water and allow pressure to build so steam flashing can produce periodic eruptive discharge.

Yellowstone's geothermal features

Yellowstone's hotspot-driven magmatism supplies abundant subsurface heat that warms groundwater, producing the park's extensive geothermal features.

Hydrothermal alteration

Hydrothermal alteration occurs at higher temperatures and pressures and often precipitates minerals (veins/ores), whereas karst dissolution is low-temperature carbonate dissolution by weak acids.

Hazards of supervolcano calderas

Supervolcano calderas are hazardous because massive eruptions, caldera collapse, ashfall, pyroclastic flows, seismicity, and long-lived geothermal unrest can devastate regional and global systems.

Flash flooding in deserts

Intense rain on impermeable or hydrophobic desert soils produces rapid runoff that funnels into narrow channels, causing sudden, powerful floods.

Exotic vs ephemeral streams

Exotic streams are perennial rivers entering deserts from wetter source regions, while ephemeral streams flow only briefly after local precipitation.

Interior drainage significance

Interior drainage traps water and sediments in closed basins, producing playas, salinas, and highly variable local hydrology.

Mechanisms of wind erosion

Deflation lifts and removes loose particles leaving desert pavement, while abrasion sands blasts and scours exposed rock surfaces.

Wind transport processes

Saltation hops sand-sized grains in short leaps, and surface creep rolls larger particles pushed by saltators.

Formation of playas and pediments

Playas form from evaporated basin lakes; pediments are broad bedrock slopes at mountain fronts; inselbergs are isolated resistant rock hills left after surrounding erosion; yardangs are wind-sculpted streamlined ridges in soft sediments.

Water vs wind in deserts

Running water (episodic floods and fluvial erosion) dominates landscape sculpting, while wind mainly redistributes loose sediment and polishes surfaces.

Glacier formation and movement

Glaciers form where snow accumulation exceeds melt and move by internal plastic deformation of ice and by basal sliding over lubricated beds.

Equilibrium line controls

The equilibrium line and net accumulation/ablation are controlled by climate—primarily temperature, precipitation, solar radiation, and local topography.

Glacial erosion and deposition

Glaciers erode by abrasion (ice-borne debris grinding bedrock) and plucking (freeze-thaw removal), and deposit unsorted till directly and sorted outwash via meltwater.