Geological Processes: Groundwater, Glaciers, Wind and Shorelines

Set of vocabulary flashcards covering key concepts related to groundwater, glaciers, wind and desert processes, and shoreline dynamics.

Groundwater

Underground water stored in the pore spaces of soil, sediment, and rock.

Porosity

The percentage of a material's total volume that is pore space.

Permeability

A material's capacity to transmit fluids.

Zone of Aeration

The zone above the water table that contains both air and water.

Zone of Saturation

The area below the water table in which all pore spaces are filled with water.

Water Table

The surface that separates the zone of aeration from the underlying zone of saturation.

Spring

Place where groundwater flows or seeps out of the ground.

Water Well

Well made by digging or drilling into the zone of saturation.

Cone of Depression

A cone-shaped depression around a well where water is pumped from an aquifer faster than it can be replaced.

Artesian System

A confined groundwater system with high hydrostatic pressure that causes water to rise above the level of the aquifer.

Sinkhole

A depression in the ground that forms by the solution of underlying carbonate rocks or by the collapse of a cave roof.

Karst Topography

Landscape consisting of caves, sinkholes, and solution valleys formed by groundwater solution of carbonates.

Cave

Natural subsurface opening generally connected to the surface and large enough for a person to enter.

Hot Spring

Spring in which the water temperature is warmer than the temperature of the human body.

Geyser

Hot spring that periodically ejects hot water and steam.

Glacier

Mass of ice on land that moves by plastic flow and basal slip.

Valley Glacier

Glacier confined to a mountain valley or an interconnected system of mountain valleys.

Continental Glacier

A glacier that covers a vast area and is not confined by topography (also known as an ice sheet).

Firn

Granular snow formed by partial melting and refreezing of snow; transitional material between snow and glacial ice.

Glacial Ice

Water in the solid state within a glacier.

Plastic Flow

Flow that takes place in response to pressure and causes deformation with no fracturing.

Basal Slip

Movement involving a glacier sliding over its underlying surface.

Glacial Budget

Balance between expansion and contraction of a glacier in response to accumulation versus wastage.

Zone of Accumulation

Part of a glacier where additions exceed losses and the glacier's surface is perpetually covered with snow.

Zone of Wastage

Part of a glacier where losses from melting, sublimation, and calving exceed the rate of accumulation.

Abrasion

Process whereby rock is worn smooth by the impact of sediment transported by the glacier, running water, waves, or wind.

Glacial Polish

Smooth, glistening rock surface formed by the movement of sediment-laden ice over bedrock.

Glacial Striation

Straight scratch rarely more than a few millimeters deep on a rock caused by the movement of sediment-laden ice.

U-Shaped Glacial Trough

Valley with steep or vertical walls and a broad flat floor formed by the movement of a glacier through a stream valley.

Fjord

An arm of the sea extending into a glacial trough eroded below sea level.

Hanging Valley

A tributary glacial valley whose floor is at a higher level than that of the main glacial valley.

Cirque

Steep-walled bowl-shaped depression on a mountainside at the upper end of a glacial valley.

Arete

Narrow, serrated ridge between two glacial valleys or adjacent cirques.

Horn

Steep-walled, pyramid-shaped peak formed by the headward erosion of at least three cirques.

Glacial Drift

Collective term for all sediment deposited by glacial ice and by meltwater streams.

Till

All sediment deposited directly by glacial ice.

Stratified Drift

Glacial deposits that show both stratification and sorting.

Erratic

Rock fragment carried some distance from its source by a glacier.

End/Terminal Moraine

Pile or ridge of rubble deposited at the terminus of a glacier.

Ground Moraine

Layer of sediment released from melting ice as a glacier's terminus retreats.

Lateral Moraine

Ridge of sediment deposited along the margin of a valley glacier.

Medial Moraine

Moraine carried on the central surface of a glacier formed where two lateral moraines merge.

Drumlin

Elongate hill of till.

Outwash Plain

The sediment deposited by meltwater discharging from a continental glacier's terminus.

Esker

Long, sinuous ridge of stratified drift deposited by running water in a tunnel beneath stagnant ice.

Milankovitch Theory

An explanation for the cyclic variations in climate and the onset of ice ages as a result of irregularities in Earth's rotation and orbit.

Desertification

The expansion of deserts into formerly productive lands.

Ventifact

Stone with a surface polished, pitted or grooved by wind abrasion.

Deflation

Removal of loose sediment by wind.

Desert Pavement

Surface mosaic of close-fitted pebbles, cobbles, and boulders found in dry regions resulting from wind erosion of finer particles.

Dune

Mound or ridge of wind-deposited sand.

Barchan Dune

Crescent-shaped dune with tips pointing downwind.

Longitudinal Dune

Long ridge of sand generally parallel to the direction of the prevailing wind.

Transverse Dune

Ridge of sand with its long axis perpendicular to the wind direction.

Parabolic Dune

Crescent-shaped dune with its tips pointing upwind.

Desert

Any area that receives less than 25 cm of rain per year, has a high evaporation rate, poor soils, and vegetation on less than 25% of the surface.

Playa

Dry lake bed found in deserts.

Mesa

Broad, flat-topped erosional remnant bounded on all sides by steep slopes.

Butte

Isolated steep-sided, pinnacle-like hill formed when resistant cap rock is breached, allowing erosion of less resistant underlying rocks.

Wave

An undulation on the surface of a body of water resulting in the water surface rising and falling.

Wave Base

The depth corresponding to about one-half wavelength, below which water is unaffected by surface waves.

Fetch

The distance the wind blows over a continuous water surface.

Breaker

A wave that steepens as it enters shallow water until its crest plunges forward.

Wave Refraction

The bending of waves so that they move nearly parallel to the shoreline.

Longshore Current

A current resulting from wave refraction found between the breaker zone and a beach.

Wave Cut Platform

Beveled surface that slopes gently seaward formed by the erosion and retreat of a sea cliff.

Marine Terrace

Wave-cut platform now above sea level.

Beach

Deposit of sediment extending landward from low tide to a change in topography or where permanent vegetation begins.

Spit

Finger-like projection of a beach into a body of water.

Barrier Island

Long, narrow island of sand parallel to a shoreline but separated from the mainland by a lagoon.

Submergent Coast

Coast along which sea level rises with respect to the land or the land subsides.

Emergent Coast

Coast where the land has risen with respect to sea level.

Sea Cave

Differential erosion of an area along the coast producing a cave.

Sea Arch

When a sea cave is eroded completely through.

Sea Stack

Remnant left after a sea arch collapses.

Longshore Drift

The movement of material along a coast by waves that approach at an angle to the shore but recede directly away from it.

Circular Orbital Motion

The motion of water particles caused by a wave as the wave is transmitted through water.