Select from the following list all the different types of mechanical weathering. Select one or more: Hydration
Frost wedging
Dissolution
Abrasion
Root wedging
The correct answer and explanation is:
Correct Answers:
- Frost wedging
- Abrasion
- Root wedging
✅ Explanation (300 words):
Mechanical weathering—also known as physical weathering—is the process that breaks down rocks into smaller pieces without changing their chemical composition. It occurs due to physical forces such as temperature changes, pressure, biological activity, and friction.
Let’s analyze each option:
1. Frost Wedging (✔️ Mechanical Weathering):
This process occurs when water enters cracks in a rock, freezes, and expands. As water freezes, it increases in volume by about 9%, exerting outward pressure on the rock. Repeated freezing and thawing cycles eventually cause the rock to break apart. This is especially common in cold climates.
2. Abrasion (✔️ Mechanical Weathering):
Abrasion involves the physical scraping or wearing down of rock surfaces by particles carried by wind, water, or ice. For example, when rivers carry sediments, they grind against rock surfaces, slowly breaking them down. It’s a purely physical process and a classic form of mechanical weathering.
3. Root Wedging (✔️ Mechanical Weathering):
As plant roots grow, they can penetrate cracks in rocks. As the roots expand, they exert pressure on the surrounding rock, eventually forcing it to split apart. Though biological in origin, root wedging causes physical fragmentation, so it is considered a mechanical process.
4. Hydration (❌ Not Mechanical Weathering):
Hydration is a chemical weathering process. It involves the absorption of water into the mineral structure, which changes the mineral’s chemical composition. For instance, the addition of water to feldspar can form clay.
5. Dissolution (❌ Not Mechanical Weathering):
Dissolution is another chemical weathering process. It involves the dissolving of minerals in water, especially acidic water. For example, limestone dissolving in carbonic acid forms caves.
Summary:
Mechanical weathering types include frost wedging, abrasion, and root wedging—all involve physical forces, not chemical changes.