Earth Notes Chapter 2 ~ Section 2 Forces of Change.
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Transcript of Earth Notes Chapter 2 ~ Section 2 Forces of Change.
Earth Earth
NotesNotes
Chapter 2 ~ Chapter 2 ~ Section 2Section 2Forces of Forces of ChangeChange
The Earth’s The Earth’s InteriorInterior
Inner CoreInner Core – – about 4,000 about 4,000 miles below the miles below the surface of the surface of the EarthEarth
Outer CoreOuter Core – – 1,400 miles 1,400 miles thick, thick, temperature temperature reaches 8500reaches 8500°F°F
Earth’s Interior Earth’s Interior (con’t)(con’t)
MantleMantle: layer of hot, dense rock – MAGMA: layer of hot, dense rock – MAGMA
Earth’s Interior Earth’s Interior (con’t)(con’t)
CrustCrust: rocky shell forming Earth’s : rocky shell forming Earth’s surface.surface.
The crust is broken into slabs of rock The crust is broken into slabs of rock called plates.called plates.
NNatural forces interact with the crust, atural forces interact with the crust, creating landforms on the surface of the creating landforms on the surface of the earth.earth.
Below the oceans, the crust is about 5 Below the oceans, the crust is about 5 miles thick. Below the continents it miles thick. Below the continents it averages 22 miles in thickness.averages 22 miles in thickness.
Earth’s Interior Earth’s Interior (con’t)(con’t) PlatesPlates - float on a melted layer in the upper mantle - float on a melted layer in the upper mantle
- carry the earth’s oceans and continents- carry the earth’s oceans and continents
InternaInternal l
Forces Forces of of
ChangeChange
The The lithosphere lithosphere — the earth’s — the earth’s crust and upper layer of the mantle crust and upper layer of the mantle — is broken into a number of large, — is broken into a number of large, moving plates.moving plates.
The Plate Tectonic Theory
The plates slide very slowly over a The plates slide very slowly over a hot, pliable layer of mantle.hot, pliable layer of mantle.
The earth’s oceans and continents ride atop of the plates.
It’s along the plate boundaries that most earthquakes and volcanoes occur due to friction and pressure that produces heat.
The Plate Tectonic Theory
Plate MovementPlate Movement
Plate movement:Plate movement: creates oceans and creates oceans and mountain rangesmountain ranges
Plate Plate MovemMovem
entent ContinentaContinenta
l Driftl Drift: the : the theory that theory that the the continents continents were once were once joined and joined and then slowly then slowly drifted apartdrifted apart
Plate MovementPlate Movement
PangaeaPangaea: gigantic super : gigantic super continent which continent which eventually broke aparteventually broke apart
Ring of FireRing of Fire A A circle of volcanic mountains
surrounding the Pacific Ocean
It is one of the most earthquake-prone It is one of the most earthquake-prone & volcano-prone areas on the planet.& volcano-prone areas on the planet.
Hot SpotsHot Spots are hot regions deep within the mantle that produce magma, which rises to the surface. Volcanic island chains form as oceanic plates drift over the hot spot.
Example: Hawaiian Islands.
VolcanoesVolcanoes Form when magma inside the earth Form when magma inside the earth
breaks through the crust. Lava flows breaks through the crust. Lava flows and may produce a large, cone-shaped and may produce a large, cone-shaped mountainmountain
They often form along plate boundariesThey often form along plate boundaries
Magma splits the earth’s surface when Magma splits the earth’s surface when plates collideplates collide
FaultFault—a break in the earth’s —a break in the earth’s crust. Movement along a fault crust. Movement along a fault can send out shock waves, can send out shock waves, causing an causing an earthquakeearthquake..
San Andreas FaultSan Andreas Fault
San Andreas San Andreas FaultFault
A devastating fire followed the 1906 earthquake in San Francisco
The San Fernando earthquake of 1971 collapsed freeway overpasses in southern California
Converging/Converging/Collision ZoneCollision Zone
Plates collide and push slowly Plates collide and push slowly against each other and form a against each other and form a collisioncollision or or converging zoneconverging zone..
If 2 oceanic plates collide, 1 slides If 2 oceanic plates collide, 1 slides under the other. Islands often under the other. Islands often form this way.form this way.
If 2 continental plates collide, If 2 continental plates collide, mountains are formed. Example: mountains are formed. Example: HimalayasHimalayas
Continental Crush / Continental Crush / CollideCollide
Spreading ZoneSpreading ZonePlates pull away from each Plates pull away from each
other and form a other and form a spreading zonespreading zone. . These areas are likely to These areas are likely to have earthquakes, have earthquakes, volcanoes, and volcanoes, and rift rift valleysvalleys (a large split along (a large split along the crest of a mountain).the crest of a mountain).
Spreading ZoneSpreading Zone
SubductionSubductionThey meet, or They meet, or CONVERGE CONVERGE and and
form a form a subduction zonesubduction zone. . *If an oceanic plate collides with *If an oceanic plate collides with a continental plate, the heavier a continental plate, the heavier oceanic plate will slide under the oceanic plate will slide under the lighter, continental plate. lighter, continental plate. This results in volcanic mountain This results in volcanic mountain building and earthquakes.building and earthquakes.
SubductionSubduction
ExternExternal al
Forces Forces of of
ChangeChange
External ForcesExternal Forces What other forces can create What other forces can create
landforms?landforms? WeatheringWeathering – a process that – a process that
breaks down rock at or near the breaks down rock at or near the surface into smaller pieces. This is surface into smaller pieces. This is a VERY slow process – thousands a VERY slow process – thousands to millions of years.to millions of years.
Mechanical Mechanical WeatheringWeathering occurs occurs when rock freezes – it when rock freezes – it can cause can cause Frost Frost WedgingWedging, a crack in the , a crack in the rock caused by freezing.rock caused by freezing.
Chemical WeatheringChemical Weathering – alters the rock’s – alters the rock’s chemical makeup by chemical makeup by changing the minerals. changing the minerals. This can actually change This can actually change one kind of rock into one kind of rock into another.another.
Important forces in Important forces in Chemical Chemical WeatheringWeathering are moisture and are moisture and carbon dioxide. carbon dioxide. Through this process caves are created.Through this process caves are created.
Acid RainAcid Rain causes another type of causes another type of chemical weathering that destroys chemical weathering that destroys forests, pollutes water and kills forests, pollutes water and kills wildlife.wildlife.
EROSIONEROSION ErosionErosion is the is the
movement of movement of weathered weathered materials materials including gravel, including gravel, soil and sand. soil and sand.
The most common The most common agents of erosion agents of erosion are are water, wind water, wind and glaciers.and glaciers.
ErosionErosion
Erosion due Erosion due to wave to wave pounding at pounding at Venus Bay, Venus Bay, South South Australia. Australia.
WATER AND EROSIONWATER AND EROSION
Moving WaterMoving Water (rain, rivers, (rain, rivers, streams and oceans) is the streams and oceans) is the greatest agent of erosion.greatest agent of erosion.
SedimentSediment – small particles of soil, – small particles of soil, sand, and gravel - are carried by sand, and gravel - are carried by the moving water and works like the moving water and works like sandpaper to grind away rocks.sandpaper to grind away rocks.
SedimentSediment Sediment from Sediment from
the River the River Rhône flowing Rhône flowing into Lake into Lake Geneva.Geneva.
http://www.classzone.com/books/http://www.classzone.com/books/earth_science/terc/content/earth_science/terc/content/visualizations/es0604/visualizations/es0604/es0604page01.cfm?es0604page01.cfm?chapter_no=visualization chapter_no=visualization
SedimentSediment
Sediment creates new Sediment creates new landforms such as landforms such as
floodplains & deltas.floodplains & deltas.
FloodplainsFloodplains
DeltasDeltas form at form at the mouth of a the mouth of a riverriver
Wind ErosionWind Erosion The second major cause The second major cause
of erosion is of erosion is windwind, , especially where there is especially where there is little water and few little water and few plants.plants. Wind ErosionWind Erosion can can
devastate one area devastate one area while benefiting while benefiting another – HOW?another – HOW?LoessLoess – windblown – windblown deposits of mineral-deposits of mineral-rich dust rich dust
GLACIERS CAUSE GLACIERS CAUSE EROSION?EROSION?
Glaciers Glaciers are slow are slow moving moving sheets of sheets of ice that ice that are are formed formed over over many many years.years.
GLACIERSGLACIERS
How do they cause erosion?How do they cause erosion?
The movement cuts though land The movement cuts though land creating lakes.creating lakes.
They melt away and then rebuild They melt away and then rebuild again over thousand of years.again over thousand of years.