Great Wall of China: scientists make SHOCKING discovery about monument

A Great Wall of Chinaone of the most famous tourist attractions in the world, has portions of rammed earth, built with the compression of natural materials, which have generated concern because they are a weak point in the structure of the monument.

According to a recent study, what protects this part of the wall is a natural line created over time and which works as if it were a defense mechanism against deterioration.

We are talking about a kind of “living skin”, which covers the soil and is made up of small plants and rootless microorganisms known as biocrusts. According to scientists, they are responsible for ensuring the wall’s permanence.

The study was published in December in the journal Science Advances. Biocrusts are generally common in soils in dry regions, but researchers caught the attention of the way they were formed in front of a structure built by man.

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Great Wall of China was built between 1368 and 1644, during the Ming Dynasty – Image: Reproduction

Threat or solution?

What was known, until then, from studies already published, is that lichen and moss biocrusts are capable of destroying stone structures, as, in addition to the aesthetic issue, microbes act in the production of acids and other metabolites that cause erosion and deterioration of rocks.

The issue is so serious that it was necessary to remove the plants that grew on top of the Great Wall. On the other hand, the effects of biocrusts are positive when it comes to soil and land landmarks.

They act in a different way and manage to increase the stability of the monument, resulting in resistance to erosion.

The new study examined samples taken from more than 300 miles (483 kilometers) along the wall, across eight different sections of rammed earth. It is worth remembering that the monument was built between 1368 and 1644, during the Ming Dynasty.

More than two-thirds of the area examined is covered by biocrusts. The analyzes concluded that regions with the so-called “living skin of the Earth” have up to three times more strength and resistance than those that are not covered by it.

“They thought this type of vegetation was destroying the Great Wall. Our results show the opposite. Biocrusts are widespread on the Great Wall and their existence is very beneficial for its protection”, says soil science professor Bo Xiao, from China Agricultural University.

What are biocrusts?

Biocrusts are composed of components such as cyanobacteria, algae, mosses, fungi and lichens. They are generally found in the surface layer of the soil in drier regions and cover around 12% of the surface of the soil. Earth.

On average, they take decades to form and function like a miniature ecosystem. Despite their small size, they are capable of stabilizing the soil, increasing water retention and regulating carbon and nitrogen fixation.

In the case of the Great Wall of China, areas with biocrusts have porosity, erodibility, salinity and water retention up to 48% lower than areas without the presence of “living skin”. The increase in stability and resistance reaches 321%.

“[Biocrostas] they cover the Great Wall like a blanket that separates the Great Wall from air, water and wind”, points out Professor Xiao.