What provides the force that moves the tectonic plates?
Convection Currents
Which layer of the earth contains convection currents?
The asthenosphere (plastic mantle)
What 3 pieces of evidence did Wegener use to support his theory of continental drift?
Fossils Landforms (continents match up) Climate (glacial scratches on bedrock)
Why did scientists reject Wegener’s theory of Continental Drift?
He could not identify the force that moves the tectonic plates
What three pieces of evidence did Hess use to support his theory of Sea Floor Spreading?
Magnetic stripes on the sea floor Molten material Evidence from drilling samples
If new sea floor is constantly being created at mid-ocean ridges why isn’t the Earth getting bigger?
Other areas of the ocean floor are being subducted into the mantle
Why was the discovery of sea floor spreading so important?
It proved that new seafloor features are constantly being added
What crustal formations are created when an oceanic and continental plate collide?
Trenches, volcanic mountains
What crustal formations are created when an oceanic and oceanic plate collide?
Trenches, volcanic island arcs
What crustal formations are created when a continental and continental plate collide?
Folded Mountains
What happens along transform boundaries?
Faults (earthquakes)
What crustal formations occur at divergent boundaries?
Mid-ocean ridges, rift valleys
Where do hot spots occur?
Hot spots occur at weak spots in the Earth’s crust
What are the 4 main layers of the Earth’s interior?
Crust, Mantle, Outer core, Inner Core
How do convection currents in the mantle move the crust above?
The heating and cooling of a fluid, changes in the fluid’s density, and the force of gravity combine to set convection currents in motion. As the convection currents move, they move the crust above them.
What is the theory of Plate Tectonics?
The theory states that pieces of Earth’s lithosphere are in constant, slow motion, driven by convection currents in the mantle
What is sea floor spreading?
The process by which molten material adds new oceanic crust to the ocean floor
What do topographic maps show?
They show the surface features of an area.
What are contour lines?
Imaginary lines that join equal points of elevation on a topographic map
How are steeper areas represented on topographic maps?
Contour lines get closer together as land gets steeper
How are gradual slopes represented on topographic maps?
Contour lines get farther apart as land gets flatter
Why are earthquakes and volcanoes often found along plate boundaries?
The interaction of tectonic plates cause earthquakes and volcanoes.