Like pages in a book layers of rock with embedded fossils describes the history of the earth. Each layer represents a surface on which plants and animals live. As successive layers were covered by sediments, the remains of living organisms were buried and preserved as fossils. Rock and fossil records contain evidence of how life on Earth has changed.

Not all fossils are as large as mammoth bones. Much of the environmental history of the region comes from studying pollen found in a musk ox skull.