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Continental Drift & Plate Tectonics
Transcript of Continental Drift & Plate Tectonics
temperature reaches: 9ooo degrees F
Pressures: 45,ooo,ooo pounds per square inch The Inner Core ... Continued Flow due to temperature differences.
inner movements cause plate tectonics movement
Temperature at top: 1600 degrees fahrenheit
bottom: 4000 degrees fahrenheit. The Mantle So , How can we walk on Earth all the time if it's interior is as hot as the sun's surface? As I said before , the earth has 4 layers , these layers are: . The Inner Core
. The Outer Core
. The Mantle
. The Crust The Inner Core very high temperatures
pressures so great that the metals are squeezed together The Crust Like the skin of an apple.
3-5 miles thick under oceans.
25 miles thick under continents.
Less than 1% of Earth's volume. The Crust ... Continued Oceanic crust: 5 to 10 km thick and is composed of basalt, diabase and gabbro.
Continental crust: 30 to 50km thick , composed of less dense rock than oceanic crust.
Temperature increases with depth. Other Facts Crust is the Layer we live on.
Magma originates in lower part of crust.
Magma is molten, liquid rock. Can also contain crystals. The lithosphere Formula:
Crust+Upper Mantle= Lithosphere!
Elastic , flexes when loads are placed or removed from it. Theory Was 1st put forward by Abraham Ortelius in 1596.
Was developed by Alfred Wegener in 1912. There once was 1 super continent called pangaea... The continents drifted to their present locations. Alfred's explanation for theory: the drifting is because of Earth's rotation. Alfred's explanation wasn't accepted although other geographers noticed the continents fit together like a puzzle. 1950: geophycisits began to conside the theory.
1960: Theory was accepted by most geophycisits.
Two main points which caused the acceptance of the theory:
1. Continents fit together like a puzzle.
2. identical species live on different continents. 1885: Gondwanaland theory was proposed when Alfred Suess tried to explain the origins of oceans , continents...
He proposed that parts of the sea floor along with continents could rise and sink as the Earth cooled which caused land bridges between continents.
This made animals travel without crossing the ocean to different continents. The Continental Drift theory was superseded in 1915 when the plate tectonics theory had it's beginnings. How did the Plate tectonics theory help prove that the continental drift theory is correct? When the continental drift theory was proposed , Alfred explained that the continents drifted but he didn't explain how. Alfred explained that the movement of plate tectonics is what caused Pangaea to separate.
What exactly drives plate tectonics to move is unknown but lots of theories were made about it. Theories One of the theories about what moves the plate tectonics is that convection within the Earth's Mantle pushes the plates.
Another theory is that gravity is pulling the older, colder, and heavier ocean floor with more force than the newer, lighter seafloor. Plate Tectonics activity takes place at 3 types of boundaries , these are:
1. (divergent boundary)
2. (convergent boundary)
4. (transform boundary) Divergent Plate Boundary
Is when 2 plates move away from each other.
New crust is created , oceans are born and grow wider where plates diverge or pull apart. Volcanoes are also created.
Example of 2 divergent plates is:
1.North American plate.
2.Eurasian Plate. Convergent boundary Continental-Continental:
When two continents meet head-on, neither is subducted because the continental rocks are relatively light and, like two colliding icebergs, resist downward motion. Instead, the crust tends to buckle and be pushed upward or sideways. Oceanic-continental:
When an oceanic plate pushes into and subducts under a continental plate, the overriding continental plate is lifted up and a mountain range and a trench is created. Oceanic-Oceanic:
When two oceanic plates converge one is usually subducted under the other and in the process a deep oceanic trench is formed Example: The pacific and the North American Plates. Example: The Marianas Trench is a deep trench created as the result of the Phillipine Plate subducting under the Pacific Plate. Example Himalaya mountains , a result of two plates, the Eurasian Plate and the Australian-Indian Plate, are colliding into each other. Transform boundaries Transform boundaries neither create nor consume crust. Rather, two plates move against each other, building up tension, then releasing the tension in a sudden and often violent jerk. This causes Earthquakes. Example The San Andreas Fault is the most famous transform boundary in the world. To the west of the fault is the Pacific plate, which is moving northwest. To the east is the North American Plate, which is moving southeast. The Major Plates African Plate
North American Plate
South American Plate
Nazca Plate African Plate includes the continent of Africa, as well as oceanic crust which lies between the continent of Africa.
The African Plate is rifting in the eastern interior along the East African Rift. Antarctic Plate Covers the continent of Antarctica.
The Antarctic plate movement is estimated at least 1 centimeter/per year towards the Atlantic Ocean. Eurasian Plate The Eurasian Plate is a tectonic plate which includes most of the continent of Eurasia.
Divergent Boundary with North American plate.
The 1973 eruption of Eldfell, the volcano of the Icelandic island Heimaey, caused by the North American and the Eurasian plates moving apart, is a result of divergent plate boundary forces. Indo Australian Plate Includes the continent of Australia & extends northwest to the indian subcontinent.
The eastern part Australia is moving northward at the rate of 5.6 cm per year while the western part India is moving only at the rate of 3.7 cm per year.
There is a huge chance the plates might be separating. North American Plate The North American covers most of North America, Greenland, Cuba, Bahamas, and parts of Siberia, Iceland and the Azores.
It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia. The plate includes both continental and oceanic crust. Pacific Plate oceanic tectonic plate that lies beneath the Pacific Ocean.
A divergent boundary with the explorer plate.
Transform boundary with the North American plate.
Divergent with the Nazca plate. South American Plate Includes South America & a sizeable region of the atlantic ocean.
moving westward away from the Mid-Atlantic Ridge. Arabian Plate colliding with the Eurasian Plate.
Consists mostly of the Arabian Peninsula. Caribbean Plate Transform boundary with the North American plate.
The Caribbean Plate is a mostly oceanic tectonic plate underlying Central America and the Caribbean Sea Nazca Plate An oceanic tectonic plate in the eastern Pacific Ocean. Convergent with the South American plate. Plate Boundary Rap Did you know That we all could firewalk? The Earth's interior( inside) is made of 4 layers , 3 solid and 1 liquid which are nearly as hot as the sun's surface... The Outer Core SO HOT
Temperatures: 4000 to 9000 F.
1800 miles beneath the crust
1400 miles thick.
Composed of the melted metals nickel and iron. The Mantle Largest layer of Earth.
Composed of dense rock.
flows like asphalt. It's Quiz Time!!! There are ten major plates on Earth and many more minor ones. They float on a plastic-like part of the Earth's mantle called the asthenosphere. Folds When great stress is gradually applied to rock , it can change it's shape over time. Example: Appalachian folds of Central Pennsylvania. Faults When stresses exceed the strength of a rock it can break or fracture. Example: San Andreas Fault.