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Weathering, Erosion and Deposition. Weathering. Weathering is the wearing away of rock and can be chemical or mechanical. These mountains in Costa Rica were mechanically weathered by abrasion. Abrasion is weathering by grinding action.
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Weathering • Weathering is the wearing away of rock and can be chemical or mechanical. These mountains in Costa Rica were mechanically weathered by abrasion. • Abrasion is weathering by grinding action
These mountains in Salt Lake City, Utah, were also weathered by abrasion.
More examples of weathering on the Pacific Coast of Costa Rica are shown by these sea stacks out in the ocean. They were formed as ocean waves weathered away part of the rocksseen here.
Another example of weathering is the creation of a horn. This is a peak of a mountain that has been formed by the weathering away of rock by glaciers.
Mechanical Weathering • Process by which rocks are broken down into smaller pieces by physical forces. • Types of Mechanical weathering • Frost wedging • Plant roots • Abrasion • Burrowing of animals (animal action) • Temperature changes (freezing and thawing) • Moving water
Chemical Weathering • the process that breaks down rock through chemical changes. • The agents of chemical weathering • Water • Oxygen • Carbon dioxide • Living organisms • Acid rain
Water • Water weathers rock by dissolving it.
Oxygen • Iron combines with oxygen in the presence of water in a processes called oxidation. • The product of oxidation is rust.
Carbon Dioxide • CO2 dissolves in rain water and creates carbonic acid. • Carbonic acid easily weathers limestone and marble.
Living Organisms • Lichens that grow on rocks produce weak acids that chemically weather rock.
Acid Rain • Compounds from burning coal, oil and gas react chemically with water forming acids. • Acid rain causes very rapid chemical weathering.
Karst Topography • A type of landscape created by chemical weathering of limestone • Located in rainy regions where there is limestone near the surface, characterized by sinkholes and caves.
S:\Staff\Subject File Share\Science\6th Grade\Second Quarter Presentations\Weathering.asf
Erosion • Erosion is the movement of sediment by water, wind or ice. In this picture taken in Oregon, a gully has been created by a stream that has cut a path through soft sediment after a strong rainfall.
Erosion • Erosion has caused this bank in Squaw Creek to be cut away by the weathering of the river, forming a landform that simulates a partial cave on the left side of this picture.
Erosion • Here, erosion by longshore drift, has caused a lagoon to form along this beach in Costa Rica.
S:\Staff\Subject File Share\Science\6th Grade\Second Quarter Presentations\Erosion.asf
Deposition • Definition: deposition is the settling out of sediment that has been eroded.
Deposition • Deposition is the adding of sediment in an area as it settles out and forms new landforms. In this picture, taken in Squaw Creek, near Sisters, Oregon, rocks have been deposited along the bank of the river after heavy rains.
Deposition • In this picture, also taken in Squaw Creek, a sandbar has been formed by sediment that has been washed down the river. This might also be considered a spit.
Erosion and Deposition • Meanders are formed by the weathering of one bank of a river and the deposition of the weathered sediment on the opposite bank of the river. This creates a loop-like bend in a river, such as this one. This view was taken from an airplane over a mountain range in the midwest.
Deposition • In this picture, salt has been deposited in the Great Salt Lake, Utah. You can see the salt deposits. They appear as white areas on the edge of the water.
Landforms • http://www.classzone.com/books/earth_science/terc/content/visualizations/es1205/es1205page01.cfm?chapter_no=visualization
Erosion Control • These native plants were left undisturbed on the beach in Costa Rica, so that they would hold in the sand and prevent erosion on the beach. This is an example of permanent erosion control.
