Biological Weathering Definition, Examples, Types, Causes, Agents

Biological Weathering

Biological weathering is caused by living organisms. This type of weathering showcases both physical and Chemical Weathering. For example, plant roots penetrate cracks in the rock and slowly break the rock mechanically. The plant roots secrete certain chemicals to extract minerals, causing chemical weathering.

Animals and insects that den or nest or cave in soft rocks fall under Physical Weathering. Anthropogenic activities are one of the most effective agents of biological weathering. Some of the major driving agents influenced by anthropogenic activities are mining, quarrying, excavations, etc. which lead to significant weathering of the surface of the Earth.

Biological Weathering Meaning

The loss of minerals and ions from the environment as a result of the growth or movement of organisms is known as Biological Weathering. It also goes by the name of organic weathering. Animals, bacteria, plants, and people are its primary agents. Earthworms, termites, rodents, algae, dead plants, and animals all contribute to the fertilisation of the soil, which is advantageous for irrigation and agriculture.

In actuality, by cultivating and ploughing, people are combining and bringing the earth’s surface’s soil minerals, water, and air into touch. On the other side, these creatures create compounds that help the rock on which they dwell break down by absorbing all of its nutrients.

Biological Weathering Agents

There are mainly 4 Agents of Biological Weathering that are responsible for the Weathering process.

• Animals
• Microorganisms
• Plants
• Humans

Biological Weathering Causes

1. Roots Of Plants

Some trees grow inside of rocks, which aids in biological weathering. Roots of plants and trees delve into the soil in quest of moisture and nutrients. The joints or cracks in the rocks are traversed by the roots as they move through the soil, gradually rupturing the rock.

Additionally, larger, expanding roots may exert pressure on surrounding rocks. Additionally, some plant roots release organic acids that aid in the dissolution of rock minerals.

2. Microbial  Activity

Small creatures including bacteria, moss, lichens, and algae create organic acids. This modifies the rock’s chemical makeup and gradually erodes its outer covering.

3. Animal Burrowing

Some creatures, including moles, squirrels, and rabbits, can cause fissures in rocks. However, by making a fissure, these organisms absorb the nutrients from the rock. It progressively separates the rock into substantial pieces.

4. Anthropogenic Activities

Agriculture, mining, construction, and other human-made soil and rock fracturing are all examples of human activities. The rocks eventually break because of the fissures caused by these actions.

Read More: Types of Rocks

Biological Weathering Types

Biological Weathering can be classified into physical means and chemical means.

Biological Weathering by Physical Means

1. By Plants

Where there is water, plants can grow. By expanding into fractures and fissures in rocks and soil, tree and plant roots can often naturally weather rocks. They are therefore more likely to crack and ultimately disintegrate.

2. By Animals

Burrowing creatures like shrews, moles, earthworms, and even ants aid in biological weathering. Particularly these animals dig holes in the ground and bring rock pieces to the surface. These fragments are consequently more susceptible to other environmental conditions that can hasten their deterioration. Animals like the Piddock shell can dig through rocks to defend themselves. It can cause cracks in the rock and eat the minerals it contains by releasing acids that can dissolve them and reduce them to fragments.

3. By Humans

Like any other animal, humans can indirectly contribute to biological weathering. Even merely walking and jogging breaks up the soil into tiny fragments. Road building and planting are two instances of human endeavours that might hasten biological weathering.

Read More: Mass Movement

Biological Weathering by Chemicals Means

1. By Plants

Deeper-rooted plants often cause cracks and gaps in marble and limestone by producing acids that can corrode them over time. Rocks can break down more physically and chemically when there is more water available, which is a property of humus, an organic component of soil.

Additionally, as a plant dies, its roots and other parts begin to disintegrate and turn into organic matter, which releases carbon dioxide. Weak carbonic acid is created when CO2 combines with water (H2O), and this acid can corrode the surfaces of rocks and rock particles.

2. By Microorganisms

Even the most difficult rocks and dirt can be broken down by microorganisms, despite their small size. The minerals are freed when a fungus produces chemicals that can dissolve minerals in rocks. Algae eat these minerals, causing the rock to deteriorate more and develop cracks and crevices.

Therefore, broken rocks have a higher chance of crumbling. Actinomycetes are a class of bacteria that have successfully eroded rocks in Egypt by generating acid, solubilizing minerals, and leaching metals.

3. By Animals

Rocks can be physically broken down by ants and termites, but they can also be biologically broken down. Along with making holes and openings in the earth, these critters also make it possible for oxygen and water to easily enter the soil resulting in the disintegration of both soil and rock as well as rock fragments. When animals pass away, their bodies are transformed into compounds that, when mixed with minerals from rocks and soil, can worsen the ecosystem.

Biological Weathering Significance

• Weathering weakens the surface materials on the surface of the Earth.
• It helps in soil formation by facilitating silt, clay, and sand.
• Weathering of rocks helps in making fertile plains, beaches etc.
• Minerals created by the weathering process are supplied as nutrients for plant uptake.

Biological Weathering UPSC

The regular actions of organisms result in biological weathering. Humic acids, bioerosion, and biological rock deterioration are examples of organic processes. Biological rock dissolving is induced by bacterial activity. It results from physical changes brought on by organism migration or development as well as the addition or removal of ions and minerals from the weathering environment. It also refers to the deterioration of rock brought on by microorganisms, animals, and plants.

The topic “Biological Weathering”, which is an important element of the UPSC Exam’s Geography Syllabus, should be thoroughly studied by candidates.

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