Rocks

Scientists who study rocks attempt to answer a wide variety of questions: What do rocks and the ratios of stable to unstable isotopes within rocks tell us about the age of the Earth, the times at which the Earth's tectonic plates collided to produce mountains, and global warming? At what times were glaciers present on different continents? Where might we expect to have earthquakes and volcanic eruptions? What types of fossils occur in rocks and how do the fossils differ among rocks from all over the world? In which rocks might we find safe supplies of water, hydrocarbons, and mineral resources such as copper, diamonds, graphite, and aluminum? Although these problems are not often easy to solve, rocks supply important information about them.

Scientists examine rocks in various settings. Some scientists go out to places where rocks are exposed at the surface of the Earth in order to map occurrences and to collect samples of rocks for further study in the laboratory. Others work exclusively in the laboratory examining thin slices of rock under microscopes, determining the structure and chemical composition of individual crystals within a rock, determining the ratios of different isotopes of atoms within a crystal or rock, or examining the fossils in rocks. Scientists who work in different areas of Earth try to compare the rocks and fossils they find in order to determine how the Earth has changed through time. For example, the eastern coast of South America and the western coast of Africa share many common rocks and fossils, suggesting that these areas might have been closer in the past.

Scientists also pay close attention to several significant ongoing phenomena: large, destructive earthquakes in California and Japan; a surge in the Bering Glacier of Alaska, the largest glacier in North America; and volcanic activity in Mexico, West Indies, Indonesia, Papua New Guinea, and Italy. Scientists are actively involved in the search for safe locations to dispose of some of our dangerous wastes. Our understanding of Earth's processes are also helping unravel questions about other planets and astronomical bodies in our solar system. In addition, studies of how and where rocks form continue.