1. EQ: What is chemical and mechanical weathering?
Rocks and Weathering
EQ: What is chemical and mechanical weathering?
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2. EQ: What is chemical and mechanical weathering?
Weathering – process that breaks up rocks and other substances at the Earth’s surface
2 types, mechanical and chemical
Heat, cold, water, ice, oxygen and carbon dioxide contribute to weathering
Erosion – movement of rock particles by wind, water, ice or gravity
EQ: What is chemical and mechanical weathering?
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3. Mechanical Weathering
Mechanical weathering – rock gets broken into smaller pieces
Caused by heating and cooling, freezing and thawing, growth of plants, actions of animals, and abrasion
Abrasion- grinding away of rock by rock particles carried by water, ice, wind or gravity
Works slowly
EQ: What is chemical and mechanical weathering?
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4. Mechanical Weathering
Ice wedging
Occurs in cold climates
Water seeps into a crack in the rock, freezes (expands) and thaws (contracts) repeatedly
Cracks the rock
EQ: What is chemical and mechanical weathering?
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5. EQ: What is chemical and mechanical weathering?
Chemical Weathering
Breaks down rock through chemical changes.
Agents are water, oxygen, carbon dioxide, living organisms, and acid rain
Produces a different mineral makeup in the rock
i.e. – granite begins with minerals of feldspar, quartz and mica. After chemical weathering, granite changes feldspar to clay
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6. EQ: What is chemical and mechanical weathering?
Chemical Weathering
Creates holes or soft spots in rock
EQ: What is chemical and mechanical weathering?
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7. 5 agents of Chemical Weathering
Water – most important agent. Dissolves the rock.
Oxygen – combines with iron in the presence of water. This is oxidation(rust). Gives it a red or brown color.
EQ: What is chemical and mechanical weathering?
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8. Five agents of Chemical Weathering
Carbon Dioxide – found in air. Forms a weak acid (carbonic acid).
Living organisms – plant roots
Acid Rain – fossil fuels that pollute air with sulfur, carbon, and nitrogen compounds. Form acid.
EQ: What is chemical and mechanical weathering?
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9. EQ: What is chemical and mechanical weathering?
Rate of Weathering
2 factors that determine the rate
Type of Rock –
Depends on the minerals in the rock
Is the rock permeable?(has holes,cracks)
Climate
Average weather conditions of an area
Hot and wet climates weather rock more quickly
EQ: What is chemical and mechanical weathering?
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10. Class Work and Homework
Fill In What did I learn Confused Say Read pages G 40 – G 45, #’S 1-5
EQ: What is chemical and mechanical weathering?
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