plate tectonics why the earth is like it is. earth layers earth is made up of 5 layers: 1.inner core...
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PLATE TECTONICS
Why the Earth is Like It Is
Plate tectonics is the theory that Earth's outer layer is made up of plates, which have moved throughout Earth's history. The theory explains the how and why behind mountains, volcanoes, and earthquakes.
Continental DriftContinental Drift: Alfred Wegener's theory that all continents were once connected in a single, large landmass (called Pangaea) that broke apart about 200 million years ago and drifted slowly to their current positions.
What Did The Earth Look Like In The Past?
What evidence do we have that the continents have moved?Fossil Clues:
Fossils of similar plants and animals have been found on continents that are now very far apart, but were perhaps once joined together.
Climate clues:Evidence of glaciers can be found on land that is now tropical, because that land was once located in a colder region of our planet.
Rock Clues:Similar rock structures can be found on continents that are now far apart, again suggesting that they could have once been joined. Rocks found in the eastern US are similar to those found in western Europe.
Major Tectonic Plates:Tectonic Plates World Map (link)
Do land features continue to change? Are the continents still moving?
The earth’s tectonic plates continue to gradually move even today. The plates interact. Where one plate meets another, is called a boundary.
How do we know?Hot Spots (Hawaii, Yellowstone)
Volcanoes and EarthquakesRing of Fire – very active
region of subduction
Why Do Plates Move?Plates are “pushed” and “pulled” over the surface of the Earth due to unbalanced forces.
When convection currents reach the surface, plates are pushed apart
As the plates move away from each other, part of them are pulled into the Earth’s mantle
Plates Move Toward Each OtherThis is called Convergent Boundary – these are destructive boundaries since they deform the plates
Continent/Continent
Ocean/Continent
Ocean/Ocean
Convergence creates mountainsMost volcanoes (but not all) form along Convergent boundaries, as one plate is pushed under another and the old crust melts. As two plates rub against one another, a number of small and large earthquakes could occur near convergent boundaries.
http://geology.com/nsta/convergent-plate-boundaries.shtml
Convergence – Moving TogetherTrenches
Mountains
Structural Mountains
Volcanic Mountains
Plates Move Away From Each OtherThis is called Divergence – these are constructive boundaries since they produce new land
Africa and ArabiaNorth America
and Eurasia
Mid-Atlantic Ridge
Divergent BoundariesMost often takes place at ocean ridges.As the two sides of the crust move away from each other, magma
wells up from the Earth's interior. It then solidifies into rock as it is cooled by the sea, creating new
ocean floor. Causes some volcanoes and earthquakes to form.
http://geology.com/nsta/divergent-plate-boundaries.shtml
The ridges are zones of intense volcanic activity. In addition to forming at the bottom of oceans, these divergent boundaries can also form on continents.
When this happens, a line of volcanoes emerges.
Rift Valley – if the land is above water
Sea Floor Spreading – when the land is below water
Divergence – Moving Apart
The San Andreas Fault is undoubtedly 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.
http://geology.com/nsta/transform-plate-boundaries.shtml
Plates Move Side By Side - ***SHIFTINGThis is called Transform Boundary – 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 sudden jerk creates an earthquake.
San Andreas FaultIs a continental transform fault that runs a length of roughly 1,300 km (800 miles) through California.
Review clip(click on the link above)
ReviewDivergent: Boundary between two plates that are moving apart.Convergent: Boundary between two plates that are pushing together.Transform (Strike-slip): Boundary between two plates that are sliding past one another. *** Causes EarthquakesSubduction Zone: The area where one plate pushes down under another. Volcanoes are often created by this.
As two continental plates move toward each other, what landforms would you expect to see?
A. VolcanoesB. CliffsC. New LandD. Mountains
As two continental plates move toward each other, what landforms would you expect to see?
A. Volcanoes Incorrect
These form at edges of plates or over hot spots
As two continental plates move toward each other, what landforms would you expect to see?
B. Cliffs Incorrect
These are erosional landforms or minor uplift areas
As two continental plates move toward each other, what landforms would you expect to see?
C. New Land Incorrect
Forms when plates move apart
As two continental plates move toward each other, what landforms would you expect to see?
D. Mountains – correct - because 2 continental masses will push into each other and “crumple” the edges to form mountains
Where would you find the newest land on Earth?A. In areas of continental convergenceB. In areas where two ocean plates come
togetherC. In areas where plates are moving apartD. In areas where two plates are sliding past each
other
Where would you find the newest land on Earth?A. In areas of continental convergenceIncorrect
Mountains would form here from existing land.
Where would you find the newest land on Earth?B. In areas where two ocean plates come
togetherIncorrect
You would find trenches in this area.
Where would you find the newest land on Earth?D. In areas where two plates are sliding past each
otherIncorrect
You would find land movement but not new land being formed
Where would you find the newest land on Earth?C. In areas where plates are moving apartCorrect
When plates move apart it is due to magma reaching the surface. When magma cools new land is formed.
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