Rocks are made up of different minerals, broken pieces of crystals, or broken pieces of rocks. Some rocks are made of the shells of once-living animals, or of compressed pieces of plants. What a rock is made of, the shapes of the grains, and how the grains fit together all provide valuable clues to help us unlock the rock's history hidden within.
Rocks are divided into three basic types depending on how they were formed: igneous, sedimentary, and metamorphic.
Natural objects, such as rocks and minerals, contribute to the beauty and wonderment of the National Parks and should be left, as they were found, so that others can experience a sense of discovery.