37 terms

Weathering and Erosion

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weathering
the breaking down of substances such as rocks and minerals by physical, chemical, or biological processes
erosion
the movement of sediment or soil from one location to another by means of water, ice,or wind
deposition
when particles carried by water, ice, or wind, are deposited in another location
mechanical weathering
when rocks are broken down into smaller pieces without being changed chemically
ice wedging
a type of mechanical weathering where water repeatedly freezes and thaws, exerting pressure on surrounding rock
chemical weathering
the kind of weathering that changes the chemical composition of rock
carbonic acid
forms when water mixes with carbon dioxide in air or soil
tropical climates
where chemical weathering is most rapid, due to warm and moist conditions throughout most of the year
oxidation
a chemical reaction that causes materials containing iron to rust
soil
a mixture of weathered rock, organic matter, water, and air
organic matter
decomposed leaves, twigs, roots, and other materials in soil related to living things
topography
the arrangement of the natural and artificial physical features of an area
climate
the weather conditions prevailing in an area in general or over a long period
factors that affect soil formation
parent rock, slope of land, climate, time, organisms
agents of erosion
gravity, ice, wind, and water
gravity
the invisible force that pulls everything on Earth toward its center
mass movement
erosion that occurs when gravity alone causes rock or sediment to move down a slope
creep
the process in which sediments move slowly downhill, often due to freezing and thawing
slump
occurs when a mass of rock or sediment moves downhill, leaving a curved scar
rock slide
when layers of rock break free from the side of a cliff or mountain and slide to the bottom, often causing destruction in the process
mudflow
when heavy rains or melting snow and ice saturate sediments, causing wet sediment to flow downhill
glacier
a large, deep mass of ice formed over many years
cirque
a large bowl in a mountaintop formed by valley glaciers
till
sediment deposited directly from glacier ice
outwash
sand and gravel deposits laid down by streams flowing away from melting glaciers
deflation
erosion of land by wind
desert pavement
larger sediments left behind in a desert after small particles have been carried away by wind
abrasion
erosion caused by wind that is carrying sediment wearing down other rocks
loess
a deposit of fine, windblown sediment
runoff
water that flows over Earth's surface
sheet flow
when water flows downhill as a thin sheet
sheet erosion
when thin sheets of water carrying loose sediment grains cause erosion as they flow downhill
rill
small channels cut into the sediment at Earth's surface caused by sheet flow
gully
a landform created by running water, eroding sharply into soil, typically on a hillside
streams
the most important agent of erosion; they cut large canyons, form valleys, and deposit sediment
delta
a large accumulation of sediment where a river enters an ocean or lake
sandbar
a long mass or low ridge of partially exposed sand built up in the water along a shore or beach by the action of waves or currents