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.