CK-12 Foundation
Ck 12: Fourth Grade Science: Earth Science: Relative Ages of Rocks
[Free Registration/Login may be required to access all resource tools.] Looks at how stratigraphy can be used to determine the relative ages of rocks, how unconformities occur, ways to match rock layers in different areas, and how...
Woods Hole Oceanographic Institution
Deeper Discovery: Earth's Anatomy
Interactive site provides information on each layer of the earth. Click on a layer to discover more about it.