Weathering and Erosion: Mechanical Weathering

The video explains mechanical weathering, where rocks are physically altered but not chemically changed. It covers processes like abrasion, temperature fluctuations, and the effects of freezing and thawing. Examples include rock flaking in Yosemite and Hoodoo formation in Bryce Canyon. Biological weathering by plant roots is also discussed.

What is the primary characteristic of mechanical weathering?

• It involves the melting of rocks.

• It physically breaks rocks into smaller pieces.

• It only occurs in desert environments.

• It changes the chemical composition of rocks.

How does abrasion affect rocks?

• It makes rocks more jagged and larger.

• It smoothens and rounds rocks.

• It causes rocks to melt.

• It chemically alters the rocks.

What natural process in Yosemite National Park contributes to mechanical weathering?

• Volcanic eruptions

• Earthquakes

• Tidal waves

• Heating and cooling of rocks

What happens to water when it freezes in rock cracks?

• It turns into a gas and escapes.

• It expands and widens the cracks.

• It evaporates and leaves the cracks empty.

• It contracts and closes the cracks.

How do plant roots contribute to mechanical weathering?

• By providing shade to the rocks

• By expanding and forcing cracks in rocks wider

• By chemically altering the rocks

• By absorbing all the water in the soil