Upper Mantle (Lithosphere and Asthenosphere) diagrams

Here is another picture of the Mantle, especially the Upper Mantle, and how it's divided into the lithosphere and asthenosphere (*you can click on the pictures to see them bigger). 

Remember, seafloor spreading can now explain Alfred Wegener's theory of continental drift, because as the seafloor spreads, it pushes away the continents too, causing them to move. This was the mechanism that explained how the continents moved, and supported Alfred Wegener now.

Here are more YouTube videos on this topic:

Seafloor Spreading

The theory of seafloor spreading states that magma rises at the mid-ocean ridge, pushing the seafloor away as a result. This theory was developed by Harry Hess.
As the seafloor is pushed away, the rocks get younger toward the edges.

Here are diagrams showing seafloor spreading. Click on them to see it bigger: