Continental Drift
Who proposed the hypothesis of continental drift?
Alfred Wegner
What does the theory of plate tectonics state?
The Earth’s crust and part of the upper mantle are broken into plates that move
What happens at a divergent boundary?
Plates move apart, new crust is formed
What causes tectonic plates to move?
Convection Currents
What is the outermost layer of Earth and is also known as the thinnest layer or the layer we live on?
Crust
What was the name of the supercontinent that Wegener said once existed?
Pangaea
What two earlier ideas were combined to form plate tectonics?
Continental drift & seafloor spreading
Give one example of a divergent boundary feature.
Mid-ocean ridge / Rift valley
NEW CRUST!!!
What makes mantle rock move in convection currents?
Heat from Earth’s core due to Radioactive decay
Which layer is liquid metal and is made mainly of nickel and iron?
Outer Core
What evidence supported continental drift besides the “puzzle-like” fit of continents?
Fossil, rock, and climate clues
What do we call the rigid layer of the crust and upper mantle?
Lithosphere
What happens at a convergent boundary between oceanic and continental plates?
Oceanic plate subducts under continental plate
In convection, what happens to hot, less dense material and to the cool, more dense material?
Heat rises
Cool Sinks
Which layer is solid made mostly of iron and is the hottest layer?
Inner Core
Why was Wegener’s idea not widely accepted at first?
He couldn’t explain the force that moved the continents
What is the “soft,” tar-like layer that lithospheric plates float on?
Asthenosphere
What type of boundary creates earthquakes but does not build or destroy crust?
Transform
How do convection currents link to seafloor spreading?
They push magma upward at mid-ocean ridges, creating new crust
Which layer makes up the 70% of Earth's Mass and contains Convection Currents?
Mantle
What discovery later helped confirm continental drift?
Seafloor spreading at mid-ocean ridges
What major geologic features form at tectonic plate boundaries?
Earthquakes, volcanoes, mountains, trenches
At which type of boundary is crust destroyed in subduction zones? Where plates collide? What is created at this boundary?
Convergent
Mountains and volcanoes
Convection Currents are found in what layer or part of what layer?
mainly in the Asthenosphere
Where would you find the Oceanic Crust and the Continental Crust?
Oceanic = under the ocean
Continental = under the continents(land)