Unit 3 pp #2 6th grade

Section1 Weathering Chapter 7 Objectives ,[object Object]

Describe how ice, water, wind, gravity, plants, and animals cause mechanical weathering.

Describe how plants and animals can shape Earth’s landscape.

Describe how water, acids, plants, and air cause chemical weathering of rocks.,[object Object]

Mechanical weathering is the breakdown of rock into smaller pieces by physical means, such as ice, wind, water, gravity, plants, or animals.,[object Object]

Ice wedging starts when water seeps into cracks during warm weather. When temperatures drop, the water freezes and expands. The ice then pushes against the sides of the crack, causing the crack to widen.,[object Object]

Section1 Weathering Chapter 7 Mechanical Weathering, continued ,[object Object]

Wind, Water, and Gravityare three forms of abrasion. Wind blows sand and silt against rock. Rocks scrape against each other as they roll along the bottom of swiftly flowing rivers. Abrasion also occurs when rocks fall on one another.,[object Object]

Animals cause weathering by burrowing in the soil and loosening rocks to be exposed to weathering.,[object Object]

Common agents of chemical weathering are water, weak acids, and air.

Water can break down even hard rock, such as granite. But it may take thousands of years.,[object Object]

Section1 Weathering Chapter 7 Chemical Weathering, continued ,[object Object]

Sulfuric and nitric acids from natural sources, such as volcanoes, can make precipitation acidic. Also, acid precipitation can be caused by air pollution from the burning of fossil fuels.

If the acidity is too high, acid precipitation can be harmful to plants and animals.,[object Object]

Acids in Living Things Living organisms such as lichens, which consist of fungi and algae, produce acids that can slowly break down rock.,[object Object]

Oxidation is a chemical reaction that occurs when an element, such as iron, combines with oxygen to form an oxide. Water speeds up the process.,[object Object]

Weathering is a process that takes a long time, however, some rock will weather faster than other rock.,[object Object]

The soft outer parts of the volcano have worn away after thousands of years of weathering, leaving just the harder, more resistant rock.,[object Object],[object Object]

A large rock has a large surface area, but it also has a large volume. Because of its large volume, the large rock will take a long time to wear down.,[object Object]

Unit 3 pp #2 6th grade

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Unit 3 pp #2 6th grade