Weathering and Soil

Chapter 4

4.1 Rocks and Weathering

• Erosion– Breaking down of rock ___________________– _______________________ of rock particles by:• Wind• Water• Ice• Gravity

into smaller piecesCarrying away/removal

4.1 Rocks and Weathering

• _____________– Breaking down and wearing away of rocks and

other substances– Forces involved:• ______________• ______________• ______________• ______________• ______________

Weathering

watericegasesheatcold

4.1 Rocks and WeatheringMechanical Chemical

rock physicallybroken up intosmaller pieces

break down rocks

uses chemical changes to break down rock

4.1 Rocks and Weathering

• Agents of mechanical weathering– Freezing and thawing• _____________________

– Release of pressure– ________________– Actions of animals– ________________

frost wedging

plant growth

abrasion

4.1 Rocks and Weathering

• Freezing and Thawing (Frost Wedging)1. Water seeps into crack and air pockets2. Water freezes and __________ making the crack

__________– Frost wedging causes ____________ and cracks in

concrete or blacktop

expandsbigger

potholes

4.1 Rocks and Weathering

• Release of pressure1. Material is removed from the rock’s surface 2. ________________________3. The release of pressure makes the outside of the

rock to _______________in layers like an onion

pressure is reduced

peel and flake

4.1 Rocks and Weathering

• Plant Growth1. __________ of plants grow into spaces or cracks2. They make the cracks bigger and _____________

apart3. As the roots get bigger they pry the spaces or

cracks ___________

Roots

spreads them

wider open

4.1 Rocks and Weathering

• Actions of Animals1. Animals _____________ in the ground2. This _____________________ up the soil– Moles, prairie dogs, gophers, some insects

burrowloosens and breaks up

4.1 Rocks and Weathering

• Abrasion1. Small particles of ______________ wear away at

exposed rocks2. Wind, water, or ice carry these particles– Works like __________

sand or rocks

sandpaper

4.1 Rocks and Weathering

• Agents of chemical weathering– ____________– Oxygen– ____________– Living organisms– ____________

Water

Carbon dioxide

Acid rain

4.1 Rocks and Weathering

• Water– ______________– Carry substances that dissolve rocks including:• Oxygen• Carbon dioxide• Other chemicals

Dissolving rocks

4.1 Rocks and Weathering

• Oxygen– Combines with _________• This is called oxidation• This forms ________

– Rust softens rock and makes it crumble and gives it a red-brown color

water

rust

4.1 Rocks and Weathering

• Carbon Dioxide– When dissolved in water it makes a weak acid

called _________________– Carbonic acid weathers rocks like ___________ ____________

carbonic acidmarble and

limestone

4.1 Rocks and Weathering

• Living Organisms– Plants’ roots produce ___________– These acids slowly ______________ around the

roots– _________ (plants-like organisms that grow on

rocks) produce weak acids that wear away rocks

weak acidsdissolve rocks

Lichens

4.1 Rocks and Weathering• Acid Rain– Rainwater is ______________– Burning of fossil fuels adds ___________ into the

air with sulfur, carbon, and nitrogen compounds– These make stronger acids in the rainwater– Acid rain falls and ____________ weathers rock

slightly acidicpollution

rapidly

4.1 Rocks and Weathering

• Factors that affect rate of weathering:– ______________• Minerals that make up the rock • Permeability of the rock

Type of rock

4.1 Rocks and Weathering

• Factors that affect rate of weathering:– ___________ (average weather conditions)• Chemical reactions occur ________ in warmer climates• ____________________

Climatefaster

Warmer = faster

4.1 Rocks and Weathering

• Factors that affect rate of weathering:– Climate (average weather conditions)• Chemical reactions occur faster in warmer climates• Warmer = faster