5.5. BIOLOGICAL ACTIVITY AND WEATHERING

Biological weathering is contribution to or removal of minerals and ions from the weathering environment and physical changes due to growth or movement of organisms.

Biological weathering occurs when living organisms interact with rocks and minerals. This can involve plants, animals, and microorganisms that chemically alter or physically break down the materials in the environment. For instance, as plants grow, their roots can penetrate into cracks in rocks, exerting pressure that can cause the rocks to break apart.

Think of biological weathering like a group of children playing outdoors. As the children dig and move the earth while playing, they change the landscape, just like organisms can change the rocks and minerals around them through their natural activities.

Burrowing and wedging by organisms like earthworms, termites, rodents etc., help in exposing the new surfaces to chemical attack and assists in the penetration of moisture and air.

Certain organisms, such as earthworms and termites, play a crucial role in biological weathering. By burrowing into the ground, they open up the soil and rock, allowing water and air to penetrate deeper. This exposure increases the chances of chemical weathering processes happening as it allows moisture to interact with minerals in the rocks, leading to their breakdown.

Imagine a sponge being soaked in water. The moisture can penetrate into the sponge's many openings, just like how air and water reach more places in the soil and rock because of the burrowing actions of these organisms.

Human beings by disturbing vegetation, ploughing and cultivating soils, also help in mixing and creating new contacts between air, water and minerals in the earth materials.

Human activities, such as farming and land development, also contribute to biological weathering. When we plough the soil, we turn it over and mix it, which allows air and water to come into contact with the minerals more effectively. This mixing can enhance weathering processes by continuously exposing new surfaces to weathering agents like moisture and temperature changes.

Consider baking a cake—when you're mixing the batter well, air gets incorporated, leading to a fluffier cake. Similarly, when humans cultivate soil, they allow air and water to mix more thoroughly with soil particles and minerals, facilitating weathering processes.

Decaying plant and animal matter help in the production of humic, carbonic and other acids which enhance decay and solubility of some elements.

The decay of organic matter contributes significantly to biological weathering as it releases organic acids into the soil. These acids can chemically react with minerals in rocks, making them more soluble and easier to break down. As organic matter decomposes, it enriches the soil with nutrients while simultaneously aiding in weathering processes.

Think of the process like how vinegar can dissolve a hard candy. Just as vinegar (an acid) interacts with the candy to break it down, the acids produced from decomposed organic matter react with rocks to help break them down into soil.

Plant roots exert a tremendous pressure on the earth materials mechanically breaking them apart.

As plant roots grow, they can push against rocks and soil, applying pressure that causes fractures. This mechanical weathering occurs as roots insert themselves into cracks and seams in the rock, causing the rock to break apart over time, facilitating further weathering and nutrient cycling in the soil.

Imagine someone trying to open a jar of pickles. If you apply steady pressure while pulling, the lid eventually pops off. Similarly, as roots grow and exert pressure, they can eventually cause rocks to crack and break apart.

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