Weathering and Erosion. Physical weathering Physical or mechanical weathering breaks rock into smaller pieces without altering their chemical composition.

Weathering and Erosion

Physical weathering

• Physical or mechanical weathering breaks rock into smaller pieces without altering their chemical composition.

• Ex) wind, water (ice), plants (roots)

• Frost wedging-when water seeps into cracks or joints in rock

•

•

Chemical weathering

• Process by which metallic elements reacts with oxygen (oxidation reaction) therefore causing a change in property

• Oxidation of minerals can cause the mineral to decompose and form new minerals

• Ex) oxidation reaction, Carbon dioxide, water

•

Water and chemical weathering

• Minerals react chemically with water

• Leaching-when minerals are transported to lower layers of rock

• Oxidation when water carries dissolved oxygen that reacts with the minerals

(forms iron oxide, rust red)

•

Acid precipitation

• Precipitation pH = 5.7 slightly acidic (carbonic acid)

• When fossil fuels are burned, sulfur dioxide and nitrogen oxides are released and may react with water in clouds to form nitric acid, nitrous acid, and sulfuric acid

•

Erosion

• A process in which the matereials of the Earth’s surface are loosened, dissolved, or worn away and transported from one place to another by a natural agent, such as wind, water, ice, or gravity

• Preventing ErosionWeathering can not be stopped, but erosion can.

• The following are common ways to prevent erosion.

• Plant vegetation

• Spread Mulch

• Build Retaining WallsBuild

• Terraces

Deposition

• The process by which material is laid down

• There is a direct relationship between the velocity of the water and the size and amount of sediment it can carry.

• Fast moving water-carries a lot of sediment

• Wider water ways flow more slowly

Other Features that shape Earth

• Oceans –waves erode coastline

• Glaciers- erode mountains

• Wind-dust storms (desert) erode landforms