Post on 27-Dec-2015
transcript
Layers of the Earth
Pre Ap - Notes: pg 113
Layers of the Earth
Layers of the EarthCrust •Crust: a layer of rock that forms
Earth’s outer skin–Includes land forms, soil, water, etc..
Layers of the EarthCrust •Basalt: Ocean crust made of dark
dense rock and is very thin•Granite: Continental crust that is less dense but is thicker (especially where mountains are)
Layers of the EarthMantle •Mantle: Layer of hot rock under the
crust•Lithosphere: upper most part of the mantle and the crust, solid
–About 100 kilometers thick
Layers of the EarthMantle •The temperature and pressure in the
mantle increases with depth•This pressure and high temperatures causes the lower part of the mantle to be soft and can flow easily, known as the asthenosphere•The mantle is 3,000 km thick
Layers of the EarthCore •Core: inner most part of the earth
consisting of 2 parts–Outer core: thick liquid of molten material–Inner core: dense ball of solid metal (iron and nickel)
Just the Facts
• The mantle makes up about 80% of the Earth’s total volume.
• Pressure at the center of the inner core may be more than 1 million times greater than air pressure at sea level.
• Crust material is 2.5-3.0 times denser than water, mantel material is 3.5-5.5 times denser than water, core material is 10-13 times denser than water
Fun Fact
• Suppose you could drive a car at 100km/hr (62 mi/hr) from Earth’s surface to the center of the core. At that speed the car would take about half an hour to drive through most continental crust, about another 29 hours to drive through the mantle, and about an additional 35 hours to drive to the center of the Earth.
Convection Currents and the Mantle
Convection Currents and the Mantle
Pre AP: Notes: Pg 114
Convection Currents and the MantleHeat Transfer
•Heat can transfer in 3 ways
1. Radiation1. Radiation
Transfer of heat energy by
electromagneticradiation
Example: waves onthe EMS scale
2. Conduction2. Conduction
Transfer of heatBy direct Contact
Example: touchinga metal spoon
In a pot of Boiling water
3. Convection3. Convection
Heat transferBy the movementOf heated liquids
And gasses
Example: Hot Air rises
Heat Transfer
Convection Currents and the MantleConvection Currents
•The difference between temperature and density of the fluid changes. This causes:
–Hot liquid to be less dense, moving it to the top–Cool liquid to be more dense, moving it to the bottom
Convection Currents and the MantleConvection Currents
Video
•The asthenosphere (middle mantle) is a soft liquid and experiences convection currents
–As the fluid close to the core heats, it rises to the top (near the lithosphere) and cools, causing it to cycle back down
Convection Currents and the MantleConvection Currents
•Convention currents in the mantle, cause the lithosphere (bottom of the crust) to move•This causes the crust of the earth to move around
Draw both pictures below in your notes
Heat rising
Coolnesssinking
Heat source
Heat Becomes
cool
Pg. 115 Draw both pictures below in your notes
Heat rising
Coolnesssinking
Heat source
Heat Becomes
cool
Drifting Continents
http://www.youtube.com/watch?v=_5q8hzF9VVE
Drifting ContinentsAlfred Wegener
•German scientist in early 1900s
Drifting ContinentsAlfred Wegener
•German scientist in early 1900s•His hypothesis stated that all the continents had once been joined together in a single land mass and have sense drifted apart
Drifting ContinentsAlfred Wegener
•German scientist in early 1900s•His hypothesis stated that all the continents had once been joined together in a single land mass and have sense drifted apart•He named the
mega continent
Pangea, which
means “all lands”
Drifting ContinentsAlfred Wegener
•Pangea existed over 300 million years ago•Pangea took tens of millions of years to move to where the continents are today
Drifting ContinentsContinental Drift and its evidence
•Continental Drift: Wegener’s idea that the continents slowly moved over Earth’s surfaces
Drifting ContinentsContinental Drift and its evidence
•Evidence from landforms: –Mountain range in Africa matches up with a mountain range in South America – European coal fields match up with North American coal fields
Drifting ContinentsContinental Drift and its evidence
•Evidence from Fossils–Fossils of the same animals (mesosaurus and lytrosaurus) have been found on different continents
•These reptiles once lived on a single land mass – Pangea
Drifting ContinentsContinental Drift and its evidence
•Evidence from Fossils–Glossopteris (fern like plant) fossils have been found in Africa, South America, Australia, India, and Antartica
Drifting ContinentsContinental Drift and its evidence
•Evidence from Climate–Evidence from fossils that the climate in South Africa was once much colder because there is evidence of glaciers
Where do you think South Africa was during Pangaea?
South Africa at the Pole
Drifting ContinentsContinental Drift and its evidence
•Evidence from Climate–Spitsbergen: island up by Norway which is covered in ice, but where fossils of tropical plants have been discovered
Where do you think Splisbergen was during Pangaea?
Drifting ContinentsContinental Drift and its evidence
Theory was not accepted by scientists…why?
Because Wegener could not identify the cause of continental drift
Sea Floor Spreading
In order to get sea floor spreading…
• We have to go back and remind ourselves about what convection currents are…
What are convection currents?
Heat rising
Coolnesssinking
Heat source
Heat Becomes
cool
The lithosphere is broken into different plates
Sea Floor SpreadingMid Ocean Ridge
•Mid Ocean Ridge: longest chain of mountains in the world under the oceans.
–Mountain range curves around the world like the seams on a baseball
Video: http://www.youtube.com/watch?v=sgDM6m0lUGY
Mid-Ocean Ridge
Sea Floor SpreadingMid Ocean Ridge
Video: Sonar video:
http://news.nationalgeographic.com/news/2011/04/110421-us-ocean-floor-mapping-vin-video/
•Sonar: device that bounces sound waves off under water objects to see their location and depth •Sonar mapped the mid ocean ridge
Sea Floor SpreadingHarry Hess •An American geologist who studied
mid-ocean ridges. •He suggested that the ocean floors move like conveyor belts, carrying the continents along with them.
–He came up with the idea of sea-floor spreading
Sea Floor Spreading
Sea Floor SpreadingSea Floor Spreading
1. At the mid-ocean ridge, molten material rises from the mantle and erupts.
2. Molten material then spreads out, pushing older rock away on both sides of the ridge
Sea Floor SpreadingSea Floor Spreading
3. As the molten material cools, it forms a strip of solid rock in the center of the ridge.
4. Eventually, more molten material will erupt and the cycle will begin again
Sea Floor SpreadingSea Floor Spreading
This process continually adds new material to the sea floor
Question???
Video: http://www.youtube.com/watch?v=GyMLlLxbfa4
Sea Floor SpreadingSea Floor Spreading
• Deep-Ocean Trench: under water canyon where deep oceanic crust bend downward into the mantle
• Subduction: Process by which the ocean floor sinks beneath a deep-ocean trench into the mantle
Video: http://www.youtube.com/watch?v=ryrXAGY1dmE
Sea Floor SpreadingSea Floor Spreading
• Evidence1. molten material2. magnetic stripes (video: http://www.youtube.com/watch?v=BCzCmldiaWQ)
3. drilling samples: drilling sample show younger rocks on the ridge
The Theory of Plate Tectonics
The Theory of Plate TectonicsPlate Tectonics
Plate tectonics: Theory that explains the formation, movement, and subduction of Earth’s plates
The Theory of Plate TectonicsPlate Tectonics
• The lithosphere is broken into separate sections called plates
• The plates fit closely together along cracks in the lithosphere
The Theory of Plate TectonicsPlate Tectonics
How do the plates move?• As the convection currents under the
lithosphere move, they cause the plates to move
• One plate cannot move without effecting another plate
The Theory of Plate TectonicsPlate Boundaries
• Faults: breaks in the earth’s crust• Faults are formed along plate
boundaries
The Theory of Plate TectonicsPlate Boundaries
There are three types of plate boundaries• Transform Boundaries • Divergent Boundaries • Convergent Boundaries
The Theory of Plate Tectonics
TransformBoundary
Motion Sliding past one another
Effect Shallow Earthquakes
Topography Fault
Volcanic Activity
Yes, Ring of Fire
The Theory of Plate TectonicsDivergent Boundary
Motion Move away from one another
Effect Oceanic Lithosphere created
Topo-graphy
Ridge or Rift valley(Mid ocean ridge or African Rift Zone)
Volcanic Activity
Yes – formed from magma in the mantle, Ring of Fire
The Theory of Plate TectonicsConvergent Boundary
Motion Move together or collide
Effect Oceanic Lithosphere destroyed, deep earthquakes
Topography
Trench, mountains, Island arcs
Volcanic Activity
Yes – as the plate submerges, it melts and can rise back up to the surface as lava
The Theory of Plate TectonicsPlate Boundaries
Convergent Boundaries• When plates converge, their
density will depend on what happens
The Theory of Plate TectonicsPlate Boundaries
Oceanic – Continental Convergent Boundary
• Oceanic crust is more dense, so it will go under the continental crust forming trenches and volcanoes
The Theory of Plate TectonicsPlate Boundaries
Oceanic – Oceanic Convergent Boundary
• The more dense oceanic crust will go under the less dense oceanic crust forming trenches and volcanoes
The Theory of Plate TectonicsPlate Boundaries
Continental – Continental Convergent Boundary
• Plate collide up, folding together to create mountains