Identifying locations where abundant and interesting fossils are found is a paleontologist’s first step in unraveling Earth history. First, rocks of the right age need to be identified. Desert areas are better for fossil hunting because the rocks are better exposed and weathering processes have not degraded the rocks or their fossils. But there are a lot of desert areas in the world and it is not possible to search them all on foot. Paleontologists now use satellites to locate good fossil sites. This Landsat image of Mongolia’s Gobi Desert allowed researchers to locate exposed sedimentary rocks. While the true-color image gave a broad look at the area of interest, the false-color image shown here elucidates so much more. Different colors highlight vegetation and individual rock types. By studying the different colors scientists can single out the area they think is most likely to produce fossils. In this chapter, you will learn about some of the ways that scientists study the history of Earth and how they use clues from rocks and fossils to piece together pictures of how the Earth has changed over billions of years.

^{Courtesy of Barbara Summey/NASA. earthobservatory.nasa.gov/IOTD/view.php?id=602. Public Domain.}