http://geology.usgs.gov/index.htm - This is
The U.S. Geological Survey home page. Here
you will find the most up-to-date news and
publications, research, and information
pertaining to the field of geology.
http://www.cliffsnotes.com/WileyCDA/CliffsRe
viewTopic/Geology.topicArticleId-9605.html
-
Cliffs Notes provides quite a few free articles
to help you understand the science behind
the earth's structure.