Story in the Rocks Leah Himes, Mitch Hess, and Rachel Kimble

Weathering and Erosion Weathering is a chemical and physical process that breaks down rocks at earth’s surface. Erosion is the process by which water, ice, wind or gravity moves weathered rock or soil. Erosion is simply movement down slope due to gravity when a rock particle moves. Weathering involves two processes that work in concert to decompose rocks.

Weathering Chemical weathering involves a chemical change in at least some of the minerals in a rock. Physical weathering involves physically breaking down rocks into fragments.

Erosion The main agent of erosion is running water because the surface features come directly from the action of running water both on surface and underground. Sheet erosion is a type of erosion on sloping farmland in which rain washes away a thin layer of topsoil. What caused the Grand Canyon would be erosion by the Colorado River uplift.

Sediment and Deposition Deposition is the process in which sediment is laid down in new locations. Sediment is earth materials deposited by erosion. Sediment is an organic material that comes from rocks, and its related to deposition because deposition lays the sediment in new locations.

Rock Cycle The Rock Cycle is the process in which rocks are formed, altered, destroyed and reformed. Igneous rock- they can be formed above or underground from molten magma that cools either fast or slowly. Sedimentary rock- Formed in layers, from deposition of sediment, as certain rocks Metamorphic rock- Rocks that are “morphed” into another rock, once sedimentary and igneous rocks. They had been under tons of pressure.

Fossils Fossils are any remains, or trace, of living things of a former geologic age. Fossils are most likely to be found in sedimentary rocks. Most fossils form when animal or plant remains are buried into rocks, mud, tar, volcanic ash or ice and take millions of years to form.

Geological Time Scale When rock is buried, the newer layers are on top, covering the older layers. This is called the Law of Superposition. By figuring out when all of the rock layers were formed, scientists can figure out how old rocks and fossils are. Ex: if the first rock layer is 65 million years old, any fossils in that layer must be 65 million years old also.