7-1 Rocks and Weathering
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Transcript of 7-1 Rocks and Weathering
WEATHERING AND SOIL
FORMATIONChapter 7
ROCKS AND WEATHERING
Chapter 7 Section 1
EFFECTS OF WEATHERING
Weathering is the process that breaks down rock and other substances at Earth’s surface
Heat, cold, water, and ice all contribute to weathering
Oxygen and Carbon Dioxide also contribute
Forces of weathering break rocks into smaller and smaller pieces
Erosion is the movement of rock particles by wind, water, ice, or gravity
WHAT IS THE DIFFERENCE BETWEEN WEATHERING AND EROSION?
Weathering is the process the process that breaks down rock and other materials at Earth’s surface, while erosion is the movement of rock particles by wind, water, ice, or gravity
MECHANICAL WEATHERING
Mechanical Weathering- type of weathering in which rock is physically broken into smaller pieces
Mechanical weathering breaks rock into pieces by freezing and thawing, release of pressure, growth of plants, actions of animals, and abrasion
Abrasion- the grinding away of rock by rock particles carried by water, ice, wind, or gravity
Mechanical weathering works slowly over time and can wear away whole mountains
Ice wedging- frozen wedges of ice in rocks widen and deepen cracks
CHEMICAL WEATHERING
Chemical weathering- process that breaks down rock through chemical changes
Agents of chemical weathering include water, oxygen, carbon dioxide, living organisms, and acid rain
Chemical weathering creates holes or soft spots in rock, and rocks break apart more easily
Water
Water is the most important agent of chemical weathering
Water dissolves rocks
Oxygen
Oxygen in the air combines with iron causing oxidation
Carbon Dioxide
Living Organisms
CO2 dissolves in rainwater and forms carbonic acid
Carbonic acid easily weathers marble and limestone
Roots of organisms push into cracks in rocks
Plants roots produce weak acids that slowly dissolve rock
Lichens- plant like organisms that grow on rocks- also produce weak acids
Water is the most important agent of chemical weathering
Water dissolves rocks
Acid Rain
LICHEN
RATE OF WEATHERINGType of Rock
The minerals that make up the rock determine how fast it weathers
Rocks that dissolve easily in water weather more quickly
Permeable- a material is fully of tiny, connected air spaces that allow water to seep through it
Permeable rock weathers at a fast rate
Climate Climate- the average
weather conditions in an area
Chemical and mechanical weathering occur faster in wet climates
Rainfall provides the water needed for chemical changes as well as for freezing and thawing
Chemical reactions occur faster at higher temperatures
REVIEW 1. What factors cause mechanical weathering?
Freezing and thawing, heating and cooling, growth of plants, actions of animals, and abrasion
2. Describe three causes of chemical weathering.
Water that dissolves rocks, oxygen causes oxidation, carbon dioxide dissolves in rainwater, living organisms, and acid rain
3. What factors affect the rate of weathering?
Type of rock and climate
4. Explain why chemical weathering occurs faster in hot, wet climates than in cool, dry climates.
Rainfall provides the water needed for chemical changes and higher temps cause chemical reactions to occur faster