Geomorph - Reviewer for Finals

Aeolian Geomorphology

Study of landforms shaped by wind, including erosion, transport, and deposition.

Aeolian

Refers to the influence of wind as a geomorphic agent; from Aeolus, Greek god of wind.

Wind

Primary geomorphic agent in aeolian environments responsible for weathering, transport, and deposition.

Desert

A dry region with very low annual precipitation (<300 mm), sparse vegetation, and exposed surfaces.

Hyper-Arid Desert

Desert with at least 12 months without precipitation.

Arid Desert

Desert with annual rainfall less than 250 mm.

Semi-Arid Desert

Desert region receiving 250-500 mm of annual rainfall annually.

Sahara Desert

A hyper-arid desert located in North Africa.

Gobi Desert

A mid-latitude desert found in China and Mongolia.

Atacama Desert

One of the driest and hottest deserts on Earth; hyper-arid.

Mojave Desert

A major desert region in North America.

Great Sandy Desert

A vast desert region in Australia.

Atmospheric Circulation

Large-scale movement of air influenced by uneven heating of the Earth's surface.

Hadley Cell

Atmospheric cell where warm air rises at the equator and dry air descends near 30° latitude.

Ferrel Cell

Mid-latitude atmospheric cell between Hadley and Polar cells, producing variable winds.

Polar Cell

Atmospheric cell where cold, dense air descends near the poles forming polar deserts.

Subtropical Deserts

Deserts formed at around 30° N and S due to descending dry air from the Hadley Cell.

Polar Deserts

Deserts located near the poles, characterized by cold, dry conditions (e.g., Antarctica).

Aeolian Transport

Movement of sediment by wind, mainly of fine-grained, dry material.

Alluvial Plains

Wide flat areas in deserts formed by deposition of water-transported sediments.

Aeolian

________ processes involve erosion, transport, and deposition by wind.

300 mm

Deserts are regions receiving less than ________ of annual precipitation.

Antarctica

A notable polar desert is ________, one of the driest places on Earth.

Unequal Heating

Atmospheric circulation is driven primarily by ________ of the Earth's surface.

Hadley Cell

Subtropical deserts like the Sahara form under the descending dry air of the ________.

Wind Regime

Refers to wind speed, duration, and turbulence that control the capacity for sediment transport.

Sediment Characteristics

Properties such as grain size, sorting, and cohesion that influence sediment mobility.

Surface Conditions

Roughness, crusting, and obstacles that modify wind flow and erosion efficiency.

Moisture and Vegetation

Factors that increase soil cohesion and reduce sediment entrainment by wind.

Topographic Modifiers

Local relief and slope orientation affecting wind intensity and direction.

Wind Erosion

Mechanical action of wind that detaches, lifts, and wears down surface materials.

Deflation

Removal of loose, fine-grained sediments from the ground surface by wind.

Abrasion

Sandblasting process where wind-driven particles wear and smooth rock surfaces.

Desert Pavement

Interlocking layer of gravel formed as finer particles are removed by deflation.

Threshold Velocity

Minimum wind speed required to initiate particle entrainment.

Suspension

Transport of very fine particles carried high and far by wind.

Saltation

Hopping or bouncing motion of sand-sized particles driven by wind.

Creep

Rolling or sliding of larger grains pushed by saltating particles.

Deflation Hollow

Shallow depressions created by removal of loose sediment.

Blowout

Localized, deeper deflation depression formed in areas with weak vegetation.

Deflation Pan

Flat surfaces created after extensive removal of fine sediments.

Abrasion Zone

Height (1-2 meters above ground) where sand impacts are most intense.

Sand Load

Quantity of sand available for transport, influencing abrasion effectiveness.

Feedback Process

Cycle where erosion alters surface roughness, eventually stabilizing the landscape.

Vesicular Horizon

Subsurface soil layer beneath desert pavement formed by dust infilling.

Wind Regime

________ determines the wind's ability to transport sediment through speed, duration, and turbulence.

Cohesion

Moisture and vegetation increase ________, reducing sediment entrainment.

Deflation

The selective removal of fine-grained sediments by wind is called ________.

Abrasion

Mechanical wearing of rock surfaces by wind-driven sand is known as ________.

Desert Pavement

As fine materials are removed by deflation, a layer of gravel forms called ________.

Suspension

Fine particles transported high in the air by wind are moved through ________.

Saltation

Sand-sized grains typically move through bouncing motion known as ________.

Threshold Velocity

Particle entrainment begins once the wind exceeds the ________.

1-2 meters

Abrasion is most effective within ________ above the ground surface.

Blowout

A localized, deeper deflation depression formed in weakly vegetated areas is called a ________.

Protective Armor

Function of desert pavement that prevents further deflation.

Geomorphic Equilibrium

State where erosion and resistance balance, indicating landscape stability.

Landscape Maturity

Stage in arid regions marked by stabilized surfaces such as desert pavement.

Creep

Rolling or sliding of coarse grains along the ground surface.

Saltation

Bouncing or hopping movement of sand grains in short arcs.

Suspension

Transport of fine dust and silt high into the atmosphere.

Impact-Induced Ejection

Process where bouncing grains dislodge additional particles from the surface.

Lag Deposit

Accumulation of coarse material left after wind removes finer particles.

Desert Pavement

Surface of interlocking gravel and pebbles formed by prolonged deflation.

Deflation Hollow

Depression created by localized removal of loose sediment.

Blowout

Another term for deflation hollow, commonly elongated parallel to wind.

Pan

Broad, shallow depression formed by deflation, sometimes with evaporite deposits.

Playa

Large deflation basin often containing saline or evaporite surfaces.

Yardang

Streamlined ridge shaped by wind abrasion and deflation, aligned to wind direction.

Zeugen

Pedestal or mushroom-shaped rock formed due to differential erosion of soft and hard layers.

Mushroom Rock

Alternate name for zeugen, formed by wind abrasion at lower levels.

Ventifact

Rock faceted and polished by windblown sand.

Einkanter

One-sided faceted ventifact.

Zweikanter

Two-sided faceted ventifact.

Dreikanter

Three-sided faceted ventifact.

Flutes

Small grooves or ridges carved on rock surfaces by focused wind abrasion.

Aeolian Deposits

Accumulations of sediment resulting from decreasing wind velocity.

Erg

Extensive sand sea covering >125 km².

Sand Dune

Mound or ridge of sand formed by wind deposition.

Sand Sheet

Thin layer of sand where dune formation is not favored.

Loess

Wind-deposited silt forming thick blankets over large areas.

Slip Face

Steep leeward slope of a dune where sand avalanches occur.

Stoss Side

Gentle windward slope of a dune facing incoming wind.

Dune Migration

Movement of dunes downwind due to continual erosion on stoss side and deposition on slip face.

Evaporite Deposit

Minerals precipitated in pans or playas as water evaporates.

Desert Pavement

A protective surface layer of gravel formed through prolonged deflation is called ________.

Saltation

The bouncing motion of sand grains in short arcs is known as ________.

Suspension

Fine dust carried high into the atmosphere moves through ________.

Lag Deposit

Residual coarse material left after removal of finer grains is a ________.

Blowout

A depression created by localized deflation is known as a ________.

Yardang

Streamlined ridges carved by abrasion and aligned to wind direction are called ________.

Ventifact

A rock faceted and polished by windblown sand is a ________.

Loess

Wind-deposited silt forming extensive blankets is known as ________.

Erg

A massive sand sea covering more than 125 km² is called an ________.

Slip Face

The steep leeward slope of a sand dune is known as the ________.

Dune Migration Rate

Speed at which a dune moves downwind depending on size and mass.

Small Dune Migration

Migration rates up to 10-20 m/year due to low mass.

Large Dune Migration

Migration rates less than 1 m/year due to greater mass and cohesion.

Dune Formation

Process where sand accumulates due to decreasing wind velocity.

Wind Direction

Primary environmental control influencing dune shape and orientation.