Rocks & Weathering

What is weathering?

The breakdown of rocks in situ (in place) at or near the surface of the Earth.

What is the difference between weathering and erosion?

Weathering is the breakdown of rocks in place, while erosion involves the removal and transportation of weathered material.

What are the main types of weathering?

Mechanical (physical), chemical, and biological weathering.

Describe mechanical weathering.

The disintegration of rocks without any change in their chemical composition. Examples include freeze-thaw, exfoliation, and salt weathering.

What is weathering?

The breakdown of rocks in situ (in place) at or near the surface of the Earth.

What is the difference between weathering and erosion?

Weathering is the breakdown of rocks in place, while erosion involves the removal and transportation of weathered material.

What are the main types of weathering?

Mechanical (physical), chemical, and biological weathering.

Describe mechanical weathering.

The disintegration of rocks without any change in their chemical composition. Examples include freeze-thaw, exfoliation, and salt weathering.

How does freeze-thaw weathering work?

Water enters cracks in rocks, freezes and expands (by about 9%), exerting pressure that widens the cracks. Repeated freeze-thaw cycles cause the rock to break apart.

Describe chemical weathering.

The decomposition of rocks through chemical reactions, altering their mineral composition. Examples include oxidation, hydrolysis, and carbonation.

What is oxidation?

A chemical reaction where minerals react with oxygen, often in the presence of water. For example, iron in rocks can oxidize, forming iron oxide (rust).

What is carbonation?

A process where carbon dioxide in the atmosphere dissolves in rainwater, forming weak carbonic acid. This acid reacts with certain minerals in rocks (like limestone), dissolving them.

Describe biological weathering.

The breakdown of rocks by living organisms. This can include the physical effects of plant roots or burrowing animals, as well as chemical effects from organic acids produced by plants and lichens.

How do plant roots contribute to weathering?

Plant roots can grow into cracks in rocks, exerting pressure as they expand and causing the rock to fracture.

What factors affect the rate of weathering?

Climate (temperature and precipitation), rock type (mineral composition and structure), and biological activity.

How does climate influence weathering?

High temperatures and abundant moisture generally accelerate chemical weathering. Freeze-thaw is most effective in climates with frequent freeze-thaw cycles.

How does rock type affect weathering?

Rocks with many joints (cracks) are more susceptible to weathering. Different minerals also have different resistances to weathering; for example, quartz is very resistant, while limestone is easily dissolved by carbon