Internal Forces of Internal Forces of ChangeChange

Types of BoundariesTypes of Boundaries ConvergentConvergent

– Come togetherCome together

DivergentDivergent– Pull apartPull apart

TransformTransform– Slide past each Slide past each

otherother

http://www.cotf.edu/ete/modules/msese/earthsysflr/plates1.html

http://www.wwnorton.com/college/geo/egeo/animations/ch2.htm#9

Convergent BoundariesConvergent Boundaries SubductionSubduction

– One plate dives beneath anotherOne plate dives beneath another– Forms volcanic mountainsForms volcanic mountains

AccretionAccretion– As one plate slides beneath another, a trench As one plate slides beneath another, a trench

is formedis formed– Overriding plate scrapes off the subducted Overriding plate scrapes off the subducted

plate, leveling off undersea mountains and plate, leveling off undersea mountains and ridgesridges

FoldingFolding– Two continental plates collide, forming Two continental plates collide, forming

mountainsmountainshttp://www.uky.edu/AS/Geology/howell/goodies/elearning/module04swf.swf

http://www.wwnorton.com/college/geo/egeo/animations/ch2.htm#9

Divergent BoundariesDivergent Boundaries

SpreadingSpreading– Two sea plates pull apartTwo sea plates pull apart– Magma rises, creating ridges or Magma rises, creating ridges or

undersea mountain ranges (“new” land)undersea mountain ranges (“new” land)

http://www.uky.edu/AS/Geology/howell/goodies/elearning/module04swf.swf

http://www.wwnorton.com/college/geo/egeo/animations/ch2.htm#9

Transform BoundariesTransform Boundaries

FaultFault– Crack in earth’s surface Crack in earth’s surface

where two plates can slide where two plates can slide past one anotherpast one another

– When plates make a When plates make a sudden, violent shift, sudden, violent shift, earthquake!earthquake!

http://www.uky.edu/AS/Geology/howell/goodies/elearning/module04swf.swf

http://www.wwnorton.com/college/geo/egeo/animations/ch2.htm#9

External Forces of External Forces of ChangeChange

WeatheringWeathering

Definition: Definition: The breaking The breaking down of rocks down of rocks on the earth’s on the earth’s surface into surface into smaller pieces.smaller pieces.

Different from Different from erosion!erosion!

NoNo movement movement

Physical WeatheringPhysical Weathering

Caused by heat, water, ice, or Caused by heat, water, ice, or pressurepressure

Frost WedgingFrost Wedging

Frost HeavingFrost Heaving

Plant RootsPlant Roots

Burrowing of AnimalsBurrowing of Animals

Temperature ChangesTemperature Changes

Chemical WeatheringChemical Weathering

•Caused by Caused by chemical chemical reactions.reactions.•Can be Can be caused by caused by water, carbon water, carbon dioxide, dioxide, oxygen, acid oxygen, acid rainrain 1908 to 1969

Acid rain has eaten away this limestone statue.

WaterWater

Water weathers rock by dissolving itWater weathers rock by dissolving it

OxygenOxygen Iron combines Iron combines

with oxygen in the with oxygen in the presence of water presence of water in a processes in a processes called oxidationcalled oxidation

The product of The product of oxidation is rustoxidation is rust

Acid RainAcid Rain Burning coal, oil and gas react Burning coal, oil and gas react

chemically with water forming acids.chemically with water forming acids. Acid rain causes very rapid chemical Acid rain causes very rapid chemical

weatheringweathering

animation

ErosionErosion Definition: Definition: The The

process by process by which water, which water, ice, wind or ice, wind or gravity moves gravity moves pieces of rock pieces of rock and soiland soil

Different from Different from weathering!weathering!

MovementMovement

Caused by fast-Caused by fast-moving water such moving water such as rain, rivers, as rain, rivers, streams and streams and oceans. Can oceans. Can eventually form a eventually form a canyon or cliff canyon or cliff (ocean).(ocean).– Ex. Grand Ex. Grand

CanyonCanyon

Water ErosionWater Erosion

Water ErosionWater Erosion

Caused by the Caused by the movement of movement of dust, sand and dust, sand and soil. Can create soil. Can create loessloess, a fertile , a fertile soil carried by soil carried by wind.wind.– Ex. Great Ex. Great

PlainsPlains

Wind ErosionWind Erosion

Wind ErosionWind Erosion

Caused by large Caused by large pieces of ice moving pieces of ice moving across the earth’s across the earth’s surface. Can leave surface. Can leave behind behind morainesmoraines (large piles of rock (large piles of rock and debris). and debris). – Ex. Rocky Ex. Rocky

MountainsMountains

Glacial (Ice) ErosionGlacial (Ice) Erosion

Glacial ErosionGlacial Erosion

http://www.wwnorton.com/college/geo/oceansci/animations.asp

Water CycleWater Cycle

Constant movement of water on Constant movement of water on earth.earth.

Evaporation, condensation, Evaporation, condensation, precipitationprecipitation

Amount of water on earth really Amount of water on earth really never changes!never changes!

http://earthguide.ucsd.edu/earthguide/diagrams/watercycle/index.html