WEATHERING AND EROSION. Processes that change the surface of the Earth n Mechanical n Mechanical or Physical Weathering n Chemical n Chemical Weathering.

WEATHERING WEATHERING

ANDAND

EROSIONEROSION

Processes that change the Processes that change the surface of the Earthsurface of the Earth

Mechanical or Physical WeatheringMechanical or Physical Weathering Chemical WeatheringChemical Weathering ErosionErosion Tectonic Activity Tectonic Activity (volcanoes, (volcanoes,

earthquakes.etc.)earthquakes.etc.)

COMMON NATURAL FORCES COMMON NATURAL FORCES

OF CHANGEOF CHANGE

WindWind WaterWater PlantsPlants Animals (including humans)Animals (including humans)

MECHANICAL MECHANICAL WEATHERINGWEATHERING

Rocks and other materials break Rocks and other materials break apart via physical means - similar apart via physical means - similar to physical changes in chemistryto physical changes in chemistry

Chemical makeup stays the sameChemical makeup stays the same wind, burrowing animals, plants, wind, burrowing animals, plants,

iceice

CHEMICAL WEATHERINGCHEMICAL WEATHERING

Chemical reactions on the surface Chemical reactions on the surface breakdown or dissolve the minerals in breakdown or dissolve the minerals in the rock or other material - similar to the rock or other material - similar to chemical changes in chemistrychemical changes in chemistry

The chemical makeup changesThe chemical makeup changes acid rain, oxidation (rusting), plant acid rain, oxidation (rusting), plant

acids, lichen, carbonic acid (caverns)acids, lichen, carbonic acid (caverns)

EROSIONEROSION Process by which weathered Process by which weathered

materials are carried awaymaterials are carried away water, wind, ice, gravity, water, wind, ice, gravity,

humanshumans water is the MOST water is the MOST

significant force of erosionsignificant force of erosion

RIVERSRIVERSBegin as rills >> gullies >> Begin as rills >> gullies >> streams >> riversstreams >> rivers

Deposit sediment as they Deposit sediment as they lose energy - slow downlose energy - slow down

Form deltas when they reach Form deltas when they reach seas, oceans, gulfs, lakesseas, oceans, gulfs, lakes

Rivers cont.Rivers cont.

Create “V” shaped valleysCreate “V” shaped valleys Colorado River carved out Colorado River carved out

the Grand Canyon over the Grand Canyon over millions of yearsmillions of years

As they age the meanders As they age the meanders increase and oxbow lakes increase and oxbow lakes may appearmay appear

Rivers cont.Rivers cont.

Important to human Important to human activityactivity

Develops rich fertile soilsDevelops rich fertile soils Can be very destructiveCan be very destructive Provide recreation and Provide recreation and

challengeschallenges

MASS WASTING OR MASS WASTING OR MOVEMENTMOVEMENT

Gravity is the force behind mass Gravity is the force behind mass movementmovement

Landslides, mudslides, slump, Landslides, mudslides, slump, creepcreep

Water, lack of vegetation, steep Water, lack of vegetation, steep slopes can create conditions that slopes can create conditions that are ripe for mass movementare ripe for mass movement

WINDWIND Causes abrasion - sand and Causes abrasion - sand and

small particles polish and small particles polish and smooth jagged edgessmooth jagged edges

Reshapes the landscape - Reshapes the landscape - sand dunessand dunes

Can be very destructive - Can be very destructive - reach speeds over 100mphreach speeds over 100mph

GLACIERSGLACIERS Create “U” shaped valleys - Create “U” shaped valleys -

Yosemite National ParkYosemite National Park Sharp mountain peaks called Sharp mountain peaks called

Horns, Glacier Lakes Horns, Glacier Lakes (Minnesota, Great lakes)(Minnesota, Great lakes)

Move HUGE massesMove HUGE masses Studied to learn about current Studied to learn about current

and past climate changesand past climate changes

DAMS Pros and ConsDAMS Pros and Cons Prevent Prevent

floodingflooding generate generate

energyenergy create lakes, create lakes,

reservoirsreservoirs

Displace peopleDisplace people destroy habitatdestroy habitat interrupt fish interrupt fish

migrationmigration endanger wildlifeendanger wildlife change flow of change flow of

sediments andsediments and riversrivers

Human ActivitiesHuman Activities

Land Developing - Land Developing - housing, industry, housing, industry, farmingfarming

Mining of ResourcesMining of ResourcesDamming of RiversDamming of Rivers

Weathering and Weathering and Erosion are Erosion are

processes that processes that continue on a non continue on a non

stop basis.stop basis.