Weathering Basics and Types

Weathering

• Weathering is the breakdown of rocks into smaller fragments, eventually forming soil.
• Rocks change shape and size due to environmental conditions.
• Weathering can be caused by temperature changes, water, frost, plants, and animals.

Types of Weathering

• There are three main types of weathering: physical, biological, and chemical.

Physical Weathering

• Physical weathering breaks down rocks into smaller pieces without changing their chemical composition.
• Exfoliation weathering, also known as "onion-skin" weathering, is caused by extreme temperature changes (heating and cooling). This causes outer layers of rock to flake off.
• Freeze-thaw weathering is caused by the freezing and melting of water within cracks in rocks. The expansion of water when it freezes puts pressure on the rock, causing it to break apart.
• Physical weathering commonly happens in areas with extreme temperature ranges and areas with varying amounts of water and ice.

Biological Weathering

• Biological weathering involves the disintegration of rocks due to the actions of organisms, like bacteria, plants, and animals.
• Plants growing in cracks can exert pressure, causing rocks to break.
• Animal activity, such as burrowing, can create pathways and move material, contributing to the breakdown of rocks.

Chemical Weathering

• Chemical weathering changes the chemical composition of rocks by dissolving or altering minerals.
• Slow chemical weathering occurs when rainwater, which naturally contains a weak acid (carbonic acid) due to dissolved carbon dioxide, reacts with minerals in rocks, over time, causing minerals to dissolve.
• Rapid chemical weathering arises through more acidic rainwater (acid rain) caused by air pollution. Burning fossil fuels releases oxides of sulfur and nitrogen into the air, making rainwater more acidic and accelerating the chemical decay and erosion of minerals much faster.
• Acid rain quickly affects rocks, leading to faster erosion.

Rocks and Weathering

• Different rocks respond differently to weathering. The composition and structure of a rock affect its vulnerability to various types of weather.
• Investigating various types of rocks provides insight into their susceptibility to weather elements.
• Understanding the effects of weathering on different rocks is crucial for various applications (e.g., construction).

Explore the science of weathering, including its definition and the processes that break down rocks. Learn about the three main types of weathering: physical, biological, and chemical, along with specific examples like exfoliation and freeze-thaw processes.