What do seismographs detect?
What commonly happens when two continental plates collide with each other?
Mountain building. 
Scientists use fossil evidence along with rock and climate data to support this major scientific theory.
The theory of plate tectonics
When oceanic crust is forced beneath continental crust, this process occurs.
Subduction
Draw the and label the main 4 layers of the earths interior.

What is the process that drives plate tectonics? Draw a picture of this process.
Convection in the Mantle. 
This supercontinent explains why similar fossils are found on different continents today.
Pangea
New ocean crust is created by this process
Sea-Floor Spreading
What is happening to the S (secondary) Wave between 2700km and 4900km deep? 
The S-Wave is unable to pass through that layer of the earth, which is the outer core.
Draw a divergent boundary at a mid-ocean ridge.

If identical plant fossils are found on multiple continents, scientists infer this about those continents in the past.
They were once connected
Heat from Earth’s core causes this type of current in the mantle.
Convection Currents
Why do both P and S Waves change speed as they travel through the earths core?

The waves changes speed as they pass through different layers of the earths interior because the different layers have variable densities (mediums).
Explain what is happening in these images. 
Mid-ocean ridge - divergent boundary - magma rising up from the mantle - continental drift.
These deep ocean features form at subduction zones.
This soft, plastic-like layer of the mantle flows slowly and allows plates to move above it.
Asthenosphere
How do scientists use seismic data to model Earth’s layers?
What is by measuring the speed and path of waves through different materials
How does plate tectonics explain the distribution of similar fossils on different continents?
What is the continents were once connected (continental drift)
These often form along convergent boundaries where one plate sinks beneath another (subduction).
Convection in the asthenosphere causes this layer above it to move.
The Lithosphere