Geology, from the Greek words ge meaning rocks and logos meaning knowledge, is a lot more than the study of rocks. It's the study of the Earth, the materials it's made of, the events that have shaped it, and how it has changed over time. A person who studies geology is a called a geologist. Geologists study rocks as well as minerals and fossils. They study landslides, floods and volcanic eruptions. They study climate change and the history of life. Geologists use a variety of tools, such as hammers, chisels, shovels, screens and microscopes, and record their findings in notebooks. Geologists spend a lot of time outdoors collecting samples and observing the earth. This activity is called fieldwork.