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...
University of California
University of California Museum of Paleontology: Stories From the Fossil Record
This colorful, interactive site demonstrates how fossils can be used to discover a range of information about the past. Topics include Past Lives, Paleoecology, Geologic History, and Biodiversity.