Earth layers
What is the innermost Earth layer called?
The inner core
Looking at rocks in mid-ocean ridges, where do the newest rocks form?
In the center, closest to the ridge. Older rocks are farther from the ridge
What did Alfred Wegener propose?
The 7 continents were once connected in a super-continent called Pangea
What is a divergent plate boundary?
What Earth layer do we stand on?
the crust
Convergent boundaries are best known for forming what?
Mountains & volcanoes
When did Wegener propose his theory of continental drift?
1915
What is a convergent plate boundary?
Tectonic plates collide or come together
What is the mantle made of?
Magma (melted rock)
Divergent boundaries are best known for forming what? (oceans and on land)
Oceans: mid-ocean ridge
Land: rift valley (long, narrow valley)
Why did some people not believe Wegener's theory at first?
Because he had evidence that continents had drifted apart, but he could not prove how the continents had moved
What is a transform plate boundary?
Tectonic plates slide past each other horizontally
What geoscience process is happening in the mantle that causes tectonic plates to move?
Convection currents (hot magma rises, cold magma falls)
How do divergent plate boundaries lead to new oceanic crust/seafloor?
At mid-ocean ridges, magma rises from the mantle then cools
What are examples of evidence that supports Wegener's theory?
1. Fossil evidence
2. Geologic evidence (rocks match)
3. Tectonic evidence (mountains match/line-up)
4. Jigsaw fit
5. Glacial deposits
What are tectonic plates?
Tectonic plates are massive, rocky slabs forming the Earth's outer layer (lithosphere), constantly moving and fitting together like puzzle pieces
What is the lithosphere made of?
The crust & outermost (solid) part of the mantle
When thinking about seafloor spreading, new oceanic crust is formed at what plate boundaries?
Divergent boundaries
Why have continents drifted apart over time?
Divergent plate boundaries, where convection currents pull tectonic plates away from each other
What is a subduction zone?
When an oceanic plate collides with a continental plate at a convergent boundary & the oceanic plate sinks under the continental plate