Layers of the Earth Pre Ap - Notes: pg 113

Layers of the Earth

Layers of the Earth Crust Crust: a layer of rock that forms Earth’s outer skin Includes land forms, soil, water, etc..

Layers of the Earth Crust 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 Earth Mantle 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 Earth Mantle 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 Earth Core 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 Mantle Heat Transfer Heat can transfer in 3 ways 1. Radiation Transfer of heat energy by electromagnetic radiation Example: waves on the EMS scale 2. Conduction Transfer of heat By direct Contact Example: touching a metal spoon In a pot of Boiling water 3. Convection Heat transfer By the movement Of heated liquids And gasses Example: Hot Air rises

Heat Transfer

Convection Currents and the Mantle 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 Mantle 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 Mantle 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 Becomes cool Heat rising Coolness sinking Heat source

Pg. 115 Draw both pictures below in your notes Heat Becomes cool Heat rising Coolness sinking Heat source

Drifting Continents http://www.youtube.com/watch?v=_5q8hzF9VVE

Drifting Continents Alfred Wegener German scientist in early 1900s

Drifting Continents Alfred 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 Continents Alfred 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 Continents Alfred Wegener Pangea existed over 300 million years ago Pangea took tens of millions of years to move to where the continents are today

Drifting Continents Continental Drift and its evidence Continental Drift: Wegener’s idea that the continents slowly moved over Earth’s surfaces

Drifting Continents Continental 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 Continents Continental 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 Continents Continental Drift and its evidence Evidence from Fossils Glossopteris (fern like plant) fossils have been found in Africa, South America, Australia, India, and Antartica

Where do you think South Africa was during Pangaea? Drifting Continents Continental 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

Where do you think Splisbergen was during Pangaea? Drifting Continents Continental 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 Continents Theory was not accepted by scientists…why? Continental 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 Becomes cool Heat rising Coolness sinking Heat source

The lithosphere is broken into different plates

Sea Floor Spreading Mid 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 Spreading Mid 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 Spreading Harry 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 Spreading Sea Floor Spreading At the mid-ocean ridge, molten material rises from the mantle and erupts. Molten material then spreads out, pushing older rock away on both sides of the ridge

Sea Floor Spreading Sea 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 Spreading Sea Floor Spreading This process continually adds new material to the sea floor

Question??? Video: http://www.youtube.com/watch?v=GyMLlLxbfa4

Sea Floor Spreading Sea 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 Spreading Sea Floor Spreading Evidence molten material magnetic stripes (video: http://www.youtube.com/watch?v=BCzCmldiaWQ) drilling samples: drilling sample show younger rocks on the ridge

The Theory of Plate Tectonics

The Theory of Plate Tectonics Plate tectonics: Theory that explains the formation, movement, and subduction of Earth’s plates

The Theory of Plate Tectonics The lithosphere is broken into separate sections called plates The plates fit closely together along cracks in the lithosphere

The Theory of Plate 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 Tectonics Plate Boundaries Faults: breaks in the earth’s crust Faults are formed along plate boundaries

The Theory of Plate Tectonics Plate Boundaries There are three types of plate boundaries Transform Boundaries Divergent Boundaries Convergent Boundaries

The Theory of Plate Tectonics Transform Boundary Motion Sliding past one another Effect Shallow Earthquakes Topography Fault Volcanic Activity Yes, Ring of Fire

The Theory of Plate Tectonics Divergent 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 Tectonics Convergent 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 Tectonics Plate Boundaries Convergent Boundaries When plates converge, their density will depend on what happens

The Theory of Plate Tectonics Plate 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 Tectonics Plate 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 Tectonics Plate Boundaries Continental – Continental Convergent Boundary Plate collide up, folding together to create mountains