About.com is really a great all-around site, with information about tons of things. This link will take you to it’s “Basics of Geology” page, with links to hundreds of pages and images. Just one example of how great this site is? On the main page, scan down to the first main topic – “Rocks”. Then click on the link that says “Picture Gallery of Rock Types”. You’ll find excellent images and explanations of rock types…and this is just scratching the surface!
