Weathering and Erosion

Weathering Weathering is a set of physical, chemical and biological processes that change the physical and chemical properties of rocks and soil at or near the earth's surface.

More about Weathering Definition – the breakdown of rock to form sediment **Sediment is very small pieces of rock. –Weathering happens to rocks that are NOT MOVING –Weathering is part of the Rock Cycle

There are three types of weathering Mechanical [sometimes called physical] Chemical Biological

Physical Weathering Process by which rocks are broken down into smaller pieces by external conditions. Types of Physical weathering –Frost heaving and Frost wedging –Plant roots –Friction and impact –Burrowing of animals –Temperature changes

Frost Wedging

Frost Heaving

Plant Roots

Friction and Repeated Impact

Burrowing of Animals

Temperature Changes

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 CO 2 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

Biological weathering is the breakdown of rock caused by the action of living organisms, including plants, burrowing animals, and lichens. A lichen is a combination of fungus and algae, living together in a symbiotic relationship. Lichens can live on bare rock, and they break down rocks by secreting acids and other chemicals.

Topography The topography of an area includes the area’s elevation, relief and landforms. -Elevation is the height above sea level of a point on the Earth’s surface. -Relief is the difference in elevation between the highest and lowest parts of an area. -Landforms are a feature of topography, such as a hill or valley, formed by the processes that shape Earth’s surface.

Topography Map A topographic map is a map showing the surface features of an area. Topographic maps use symbols to portray land as if you were looking down on it from above.

Karst Topography A type of landscape in rainy regions where there is limestone near the surface, characterized by caves, sinkholes, and disappearing streams. Created by chemical weathering of limestone

Features of Karst: Sinkholes

Features of Karst: Caves

Features of Karst: Disappearing Streams

Erosion The process by which water, ice, wind or gravity moves fragments of rock and soil.

Water Erosion Rivers, streams, and runoff

Ice Erosion Glaciers

Wind Erosion

Mass Movements Landslides, mudslides, slump and creep landslide clip.mpeg

Deposition Deposition is the process by which sediment, rock fragments and other materials sink to the bottom of a lake or ocean.

Define/Review Section Vocabulary Weathering Sediments Physical Weathering Chemical Weathering Biological Weathering Topography Erosion Deposition