Grade 9 Geography: Weathering, Erosion, and Deposition

A complete set of vocabulary flashcards covering weathering, physical weathering processes, chemical weathering, biological weathering, erosion, deposition, and river landforms.

Weathering

The breaking down of rock into small particles by physical, chemical and biological processes.

Erosion

The removal of weathered material by the action of rivers, waves, wind and moving ice.

Deposition

The laying down of solid material in the form of sediment, such as mud and sand on a river bed or on the sea floor.

Sediment

Material, from fine mud to large rocks, that has been deposited by the agents of erosion.

Agents of erosion

The natural forces that remove weathered material, specifically rivers, waves, wind, and moving ice.

Physical weathering

The breakdown of rocks into smaller fragments through processes such as expansion and contraction, mainly due to temperature changes, freeze-thaw weathering, thermal fracturing, or pressure release.

Exfoliation

A process caused by repeated heating and cooling in areas with a large daily temperature range, where the rock's outer layers peel off in thin sheets.

Thermal fracturing

A type of physical weathering caused by temperature changes and thermal expansion or contraction without temperature changes causing fracturing.

Freeze-thaw weathering

A type of physical breakdown of rock into smaller fragments due to temperature changes.

Scree

An accumulation of loose stones or rocky debris lying on a slope or at the base of a hill or cliff.

Chemical weathering

The process by which rocks are decomposed, dissolved or loosened by chemical processes, changing the composition of rocks when water interacts with minerals.

Limestone pavement

A limestone surface that is weakened and broken up by rainwater, forming grooves called grikes and flat-topped ridges called clints.

Grike

A groove formed on a weathered limestone surface.

Clint

A flat-topped ridge formed on a weathered limestone surface.

Biological weathering

A form of weathering caused by living organisms, such as tree roots growing into cracks, burrowing animals, or organic acids given off by plants.

Tree roots

The most important agents of biological weathering, capable of breaking rocks apart by growing into cracks and joints.

Waterfall

A vertical stream of water where a river falls over the edge of a steep place, formed when softer rocks downstream are eroded away quicker than a layer of hard rock.

Rapid

An area where a river becomes shallower and has some rocks exposed above the flow surface.

Meander

A sharp bend in a river.

River cliff

A steep-sided bank formed on the outer bend of a river where water flows fastest and erosion undercuts the channel.

Ox-bow lake

An isolated meander bend left behind when a river cuts through a narrow meander neck and deposition seals off the old bend.

V-shaped valley

A deep, narrow valley formed near the river source in its upper course as fast-running water erodes vertically downwards.

Interlocking spurs

Obstacles of hard rock jutting out from alternate sides of a river valley that the river bends around.

Energy (in rivers)

The ability to do work, which determines whether a river can erode its valley, transport sediment, or drop material as deposition.

Decompose

To rot or break down.

Dissolved

To become absorbed in a liquid.

Particle

A very small piece of something.

Fragment

A small piece broken off something.

Thermal

Affected by heat.

Fracturing

Breaking, splitting or cracking something.