Tectonic plates – pieces of the crust or lithosphere that float on the asthenosphere –These...
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Transcript of Tectonic plates – pieces of the crust or lithosphere that float on the asthenosphere –These...
• tectonic plates – pieces of the crust or lithosphere that float on the asthenosphere– These plates form, move, and subduct
• plate tectonics– the theory that the Earth’s lithosphere is divided into tectonic plates that are in slow, constant motion, driven by convection currents in the asthenosphere
• What are boundary lines?
• Which sports have boundary lines?
• The edges of the tectonic plates meet at boundaries.
• There are 3 types of boundaries depending on how the plates are moving.– convergent – plates crash together– divergent – plates spread apart– transform – plates slide past each other
• The tectonic plates move very slowly – about as fast as your fingernail grows
• Review:
• What causes the plates to move?
• Convection currents
• Where do plates meet?
• Boundaries
• divergent boundaries – two tectonic plates spread or move apart
– Mid-ocean ridges, underwater volcanoes, and weak earthquakes are created at divergent boundaries
– Sometimes mid-ocean ridges rise above sea level. This creates a rift valley.
– rift valley – a deep valley created where pieces of Earth’s crust diverge on land (above sea level)• There is a rift valley in Iceland that people can actually
walk through• There are rift valleys in Africa as well
• convergent boundaries – two tectonic plates collide, crash into each other, or come together
– Continental crust can collide with other continental crust creating big mountains (Himalayas)
– Oceanic crust can collide with continental crust creating subduction zones, trenches, mountains (Andes – off the coast of South America), and volcanoes (the magma gets trapped under the mountain)
– strong earthquakes can also occur at convergent boundaries
• transform boundaries – two tectonic plates slide past each other
– Weak and / or moderate strength earthquakes are common at transform boundaries
– Crust is not formed or destroyed at transform boundaries
The San Andreas Fault is The San Andreas Fault is located at a transform boundarylocated at a transform boundary
Most of California Most of California is on the North is on the North
American Plate. American Plate. However, a part However, a part of the west coast of the west coast of California is on of California is on the Pacific Plate.the Pacific Plate.