Nature protects China’s Great Wall
The Great Wall of China is the longest wall in the world. The total length of all the sections added together is more than 13,000 miles. Researchers have recently found that parts of the wall have been preserved over time by something called a biocrust. This is a thin layer of plant life, including moss, lichen and cyanobacteria (a type of tiny living organism).
The Great Wall of China was built in sections over a period of around 2,000 years. The first parts were started around 220BC. Its purpose was to protect China from invaders coming from the north. The most famous parts of the wall were built from stone, but in some areas it was built using “rammed earth”. This is when soil and rocks are pressed together. Over time, wind and rain can easily wear down rammed earth, so scientists have often questioned how these old sections of the Great Wall have managed to survive for such a long time. A group of researchers from China Agricultural University in Beijing examined a 370-mile long section of the wall and found that more than more than two thirds of it was covered in biocrust. The scientists took some samples of the biocrust back to their lab for testing and found that the natural material was actually stronger than the rammed earth. Some pieces of the plant-based layer were up to three times stronger. This means that the biocrust has actually strengthened the wall and protected it from being worn down by weather over the years.
These findings could be important for people who manage ancient structures around the world. Although biocrust may not look appealing, its natural ability to preserve things could be a very useful tool for experts looking for ways to protect precious ancient buildings.