Human beings have used Earth’s resources since prehistoric times. We made tools from stones. We figured out how to extract precious metals from ores. We captured the energy of flowing streams. And, because it is human nature to explain everyday phenomena, we made up stories to explain how Earth was created. Students investigate sedimentary rocks and fossils from the Grand Canyon to discover clues that reveal Earth's history. They study the processes that created the rocks. Students then use the knowledge and data from rock observations to make inferences about organisms, environments, and events that occurred over Earth’s history.