A general introduction about the Earth and the moon is given in this comprehensive site. A good resource for many kinds of geophysical data is the National Geophysical Data Center . It bounces when you drop it on the floor. Rocks in the Earth's mantle behave in a similar way. Mantle convection is in principle similar to convection in a pot of water that you heat up on the stove top.
Heat is supplied from below, the earth's core, and escapes through the top, the Earth's surface.
In addition, radioactive decay also provides internal sources of energy that are important for mantle convection. Convection movies are a great way to learn about fluid dynamics. Several groups have movies investigating different convection phenomena available over the web. Before downloading any of these files, be prepared to patient as the file sizes are relatively large. Supercontinent Aggregation and Dispersal , Gurnis, Hager, and Raefsky Plume Demo , Moresi et al.