Have you seen…Potholes in

roadways?

Broken concrete in sidewalks and curbs?

These are examples of Weathering.

What is Weathering?

The process of rocks breaking down into smaller pieces.

Not to be confused with…

…Erosion

Types of Weathering.

• Chemical Weathering

and

• Mechanical Weathering aka Physical Weathering

Mechanical Weathering.

Mechanical weathering is the physical break down of a rock without changing its chemical composition.

Agents of Mechanical Weathering:

Ice Wedging

Plant Roots

Friction and Repeated Impact

Burrowing of animals

Temperature Changes

Gravity

Ice Wedging

Plant Roots

Friction and Repeated Impact

Burrowing animals

Temperature Changes

Gravity

Weathering treasures…

Not so lucky…

Chemical Weathering.

Chemical Weathering is the process in which the chemical makeup of rock is changed.

Agents of Chemical Weathering:

• Carbonation

• Oxidation

• Acid Rain

• Plant Acid

Carbonation

When water combines with carbon dioxide in the air or soil, carbonic acid forms. When carbonic acid comes in contact with rocks like limestone and marble they dissolve.

Oxidation

When you see rusty cars, red soil, or red stains on rocks, you are seeing oxidation. Oxygen reacts with iron so when some iron-containing minerals are exposed to oxygen, they can weather into minerals that are like rust. This leaves the rock weakened, and it can break apart.

Acid Rain

• Compounds from burning coal, oil and gas react chemically with water forming acids.

• Acid rain causes very rapid chemical weathering

Plant Acids

Plant roots produce acids that react with rocks. When this acid dissolves with some minerals in rocks the rock is weakened. Over time, it can break into smaller pieces.