Earths Internal Layers The crust varies in thickness 460 km oxygen silicon magnesium and iron The mantle 2885 km silicon amp oxygen Outer core 2270 km iron amp nickle liquid ID: 621939
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Slide1
The Theory of Plate TectonicsSlide2
Earth’s Internal Layers
The
crust
varies in thickness (4-60 km) oxygen, silicon, magnesium and iron
The
mantle
(2885 km) silicon & oxygen
Outer core
(2270 km) iron & nickle – liquid
Inner core
(1218 km) iron & nickle - solidSlide3Slide4
The Rock Cycle
Three types of rock found in the crust are:
Igneous
: cooled magma/lava
Sedimentary
: particles deposited by water flow. Organic/inorganic matter (fossils)
Metamorphic
: as layers build up, this rock is formed when pressure and heat become great enough to change the rock chemically
The rock cycle is completed through the tectonic process. Rock returns to the mantle, remelt, become magma, return to the crust as igneous rock.Slide5
Pangaea
Pangaea
is the name given to the single giant continent (Wegener 1912)
Panthalassa
(
single ocean
)
The theory of continental drift
states that the continents were once a single landmass that drifted apart and are still doing so.Slide6Slide7Slide8Slide9Slide10Slide11Slide12Slide13Slide14Slide15Slide16Slide17Slide18Slide19Slide20Slide21Slide22Slide23Slide24Slide25
The Theory of Seafloor Spresding
New crust emerges from the rift valley in a mid-ocean ridge.
Magma from the mantle pushes up through the rift and solidifies into new crust.
New seafloor forms at the rift valleys and mid-ocean ridges, spreading away from the ridges until it returns as part of the rock cycle at subduction zones (trenches)Slide26
Magnetic polaritySlide27
EM field reverses from time to timeSlide28
Seafloor spreading and continental drift combined by theory of plate tectonics
More than 12 separate plates
Divergent boundary: two plates moving apart
Convergent boundary: two plates push together
Transform boundary: two plates moving past each other (earthquakes)Slide29Slide30Slide31
Boundary Interactions
Divergent boundary
(normal)
Tectonic plates moves in opposite directions
Mid-oceanic ridge forms as seafloor spreading creates new crust and seafloor as magma fills the gap created over geologic time.
Convergent boundary
(reverse)
Tectonic plates move towards each other
Oceanic
subduction
under continental
:
volcanoes, earthquakes
Andes
Continental /continental convergence
: Mountains
Himaylayas
– Mt. Everest
Oceanic/oceanic: Trenches – Mariana trench,
tsunamis
Transform boundary
(strike-slip)
Tectonic plates move past each other:
Earthquakes
San
Andeas
fault in San FranciscoSlide32Slide33
Bridge across the Álfagjá
rift valley
in southwest Iceland, the boundary between the Eurasian and North American continental tectonic plates.
Slide34
Hot Spots
The hot spot theory states that hot spots are small melting areas within the mantle where thermal plumes cause magma columns to push up, breaking the crust
Hot spots do not move with tectonic plates because they originate in the mantle
Volcanic isalnd chains are the result of the plate moving over a hot spot (Hawaii, Galapagos, etc.)Slide35
Hot SpotsSlide36
Plate movement
Convection is the primary force driving seafloor spreading
Convection currents form as hot material rises and cold materials sink
A second driving force comes from the seafloor spreading
As new seafloor forms, the plates tend to slide away from the elevated mid-ocean ridgeSlide37Slide38
The end