Weathering And Erosion Weathering Erosion Erosion and weathering

Weathering & Erosion: Ø Erosion and weathering are major forces that shape Earth’s surface.

What is weathering? Weathering: The breaking down of rocks into smaller pieces. 1. Mechanical

So what is erosion? Erosion: The movement of weathered rock by wind, water, glaciers

Types of Weathering: Mechanical/Physical: Rock is physically broken into smaller pieces (larger pieces become

5 Agents of Mechanical Weathering: 1. 2. 3. 4. 5. Release of Pressure Freezing

Release of Pressure Ø As the surface of a rock is eroded, the rock

Release of pressure: rock cracks like an egg shell

Freezing & Thawing When water in the cracks of rocks freezes it expands causing

Animal Actions ØAnimals dig (burrow) through the ground to make their homes. This loosens

Plant Root Growth Plants roots can grow into cracks in the rock, slowly breaking

Abrasion l l Sand other rock particles in wind, water or ice can wear

Chemical Weathering The process that breaks down the surface of rock by chemical changes.

1. 2. 3. 4. 5. 5 Agents of Chemical Weathering Water Oxygen Carbon Dioxide

Water ØWater dissolves rock ØWater is the most important cause of chemical weathering

Oxygen Ø Oxygen + Water + Iron = Rust through the Chemical reaction called

Carbon Dioxide CO 2 + rainwater = Carbonic Acid weathers softer rock like limestone

Living Organisms ØThe roots of plants make a weak acid that slowly dissolves rocks

Acid Rain ØAcid rain causes rocks to weather very rapidly.

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Weathering And Erosion

Weathering & Erosion: Ø Erosion and weathering are major forces that shape Earth’s surface. Ø For example, the Grand Canyon was formed through erosion by the Colorado River running through it!

What is weathering? Weathering: The breaking down of rocks into smaller pieces. 1. Mechanical /Physical 2. Chemical Hulk Rock Smash!

So what is erosion? Erosion: The movement of weathered rock by wind, water, glaciers & gravity

Types of Weathering: Mechanical/Physical: Rock is physically broken into smaller pieces (larger pieces become smaller pieces of the same rock) Chemical: Rock is chemically changed (like rusting or dissolving away)

5 Agents of Mechanical Weathering: 1. 2. 3. 4. 5. Release of Pressure Freezing & Thawing Animal Actions Plant Growth Abrasion

Release of Pressure Ø As the surface of a rock is eroded, the rock begins to release pressure Ø Causes top layers of the rock to crack and flake off

Release of pressure: rock cracks like an egg shell

Freezing & Thawing When water in the cracks of rocks freezes it expands causing the crack to enlarge or get bigger. The ice melts & refreezes over & over, breaking the rock apart.

Result of Freezing & Thawing

Animal Actions ØAnimals dig (burrow) through the ground to make their homes. This loosens the soil & breaks apart rocks.

Plant Root Growth Plants roots can grow into cracks in the rock, slowly breaking them apart.

Abrasion l l Sand other rock particles in wind, water or ice can wear away exposed rock surfaces. Like sandblasting or sandpaper on wood

Chemical Weathering The process that breaks down the surface of rock by chemical changes.

1. 2. 3. 4. 5. 5 Agents of Chemical Weathering Water Oxygen Carbon Dioxide Living Organisms Acid Rain

Water ØWater dissolves rock ØWater is the most important cause of chemical weathering

Oxygen Ø Oxygen + Water + Iron = Rust through the Chemical reaction called Oxidation Ø Rock will become crumbly, soft, and appear reddish-brown in color

Rusted rock on hillside

Carbon Dioxide CO 2 + rainwater = Carbonic Acid weathers softer rock like limestone & marble as it seeps into spaces in rock. Ex: sinkholes, caves

Living Organisms ØThe roots of plants make a weak acid that slowly dissolves rocks around the plant.

Lichens grow on rock

Acid Rain ØAcid rain causes rocks to weather very rapidly.