Mechanical and Chemical Weathering

Samples of limestone, granite, and quartz are exposed to acidic groundwater. Which rock would be weathered most quickly?

• The limestone, because the acidic groundwater would dissolve the rock's calcite.

• The granite, because the acidic groundwater would oxidize the rock's iron.

• The quartz, because it would absorb the water, increasing the rock's density and placing added pressure on its molecules.

While exploring an ancient lava field, a geologist discovers a piece of granite that has a coating of soft, crumbling rust. What is the most likely explanation for this rust?

• Exposure to air has caused the iron-bearing minerals in the granite to oxidize.

• Snails and fungi living in the lava field have secreted chemicals that reacted with the granite to form rust.

• Exposure to acid precipitation has worn away the granite's exterior, revealing its soft interior.

Iron minerals in the rock react with oxygen causing it to change into rust is an example of:

• carbonation

• oxidation

• hydration

Minerals reacting with water molecules causing it to expand and put added pressure on the rock is an example of:

• carbonation

• oxidation

• hydration

A rock that contains the mineral magnesium carbonate dissolves in the presence of carbonic acid. This is an example of:

• carbonation

• oxidation

• hydration

This picture is an example of which type of mechanical weathering?

• Root Wedging

• Abrasion

• Frost Wedging

This picture is an example of which type of mechanical weathering?

• Root Wedging

• Abrasion

• Exfoliation

Which statement is true about chemical weathering?

• Rock is broken down into smaller pieces during chemical weathering.

• Living things drive the process of chemical weathering.

• New substances are formed during chemical weathering.

How is wind an agent of mechanical weathering?

• Wind carries sediment that causes abrasion of exposed rock.

• Wind carries water vapor that dissolves minerals in exposed rock.

• Wind carries oxygen molecules that react with iron in exposed rock.