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Transcript of Plate Tectonics
Layers of Earth
The lithosphere is broken up into many large and small slabs of rock called tectonic plates.
These plates fit together like a jigsaw puzzle have have been moving for billions of years
The movement of these plates is explained by Wegner's hypothesis of the continental drift
Wegner's hypothesis in which, Earth's continents were once joined in a single landmass and gradually moved
Evidence to support this hypothesis:
As scientists began mapping the sea floor, they found huge underwater mountain ranges called mid-ocean ridges
Along these ridges, cracks form in the crust. Molten rock rises through these cracks, cools, and forms new oceanic crust.
Ball of hot, solid metals (mostly iron and nickel)
Layer of liquid metal that surrounds the inner core
Earth's thickest layer, that is made up of hot rock that moves like putty (except for the upper most part)
A thin layer of cool rock
Two types of crust: Oceanic and Continental
Contains the Earth's Crust and the very top of the mantle
A layer of hotter, softer rock in the upper mantle
The lithosphere moves on top of this layer
Age of the Sea floor
The youngest rock is closest to the mid-ocean ridges while the older rock is farthest away
The farther the rock gets away from the spreading center, the more dense it gets
But if the sea floor has been spreading for millions of years, why is the Earth not getting larger?
But what drives these plates to move?
Where energy is transferred by the movement of material
Example: Boiling water
The asthenosphere moves in a similar way to boiling water. The continuation of the sinking and rising motion is called a convection current.
A motion that transfers heat energy in a material
Tectonic Plates have Different Boundaries
A plate boundary is when the edges of two plates meet:
Where plates are moving apart (most of these are found in the ocean)
Where plates are pushing together
Where plates scrape past one another
Divergent Boundaries are where plates move apart (CRUST IS CREATED)
Mid-Ocean Ridges and Rift Valleys
Mid-ocean ridges are the longest chain of mountains on Earth and most of them contain rift valleys along their center
Molten rock rises from the asthenosphere and cools due to the cold temperatures of the ocean.
Convergent boundaries are where two plates are coming together (CRUST IS DESTROYED)
There are three types of convergent boundaries:
The ocean plate sinks below the continental plate because it is colder and denser than the continental crust. This process is called subduction.
Landforms created: Coastal mountains/volcanoes and Deep-ocean trenches
One ocean plate subducts under the other ocean plate
WHICH OCEANIC PLATE IS GOING TO SUBDUCT?!
Landforms created: Island arcs and Deep-ocean trenches
Because both plates have the same density, neither plate sinks below the other
Landforms created: Mountains
Transform Boundaries are when two plates scrape past one another in opposite directions (CRUST IS NEITHER FORMED NOR DESTROYED)
These boundaries mostly occur on the ocean floor next to mid-ocean ridges but can also occur on land
What is a famous transform boundary near us?!
Get out a sheet of paper
Write a paragraph explaining how plate tectonics and the rock cycle are correlated. Be sure to include what rock types are created at what plate boundary and why. Illustrations are encouraged.