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14.5. Geological action of living beings

Destructive action of living beings

The mechanical weathering the essentially carry the plants, with its roots, creep between the cracks of the rock to break. The excavating and subterranean animals also remove rocks and mechanically altered, increasing the permeability and porosity of the soil.

The chemical weathering is more important, and made mainly some microorganisms such as bacterialichens and fungi that, the decomposing dead organic matter, produce substances which chemically attack the rock.

The biological action is essential for the formation of the soil and its horizons.

Meteorización biológica

By Heidi Soosalu (Own work) [CC BY-SA 3.0], via Wikimedia Commons

Building action of living beings

Living things are builders too, as when they form organic sedimentary rocks. The accumulation of shells, carapaces, ... of marine beings give rise to the formation of siliceous and limestone rocks on the bottom of the oceans.

The coal, formed from plant residues, and oil, from marine organisms, are also caused by the action of living things.

Corals also produce constructions like reefs, accumulating calcium carbonate for thousands of years, being able to produce important reliefs.

Seabirds produce guano, with their excrement rich in phosphorus.

The presence of vegetation, especially on slopes, largely prevents erosion, so it could also be considered as a geological action. It also favors infiltration, thereby reducing runoff water and increasing groundwater in aquifers.

Arrecife de coral en la isla de la Providencia, Colombia

By luis barreto from MED, - COL (Providencia) [CC BY 2.0], via Wikimedia Commons