Scientists in China have conducted an analysis of the vegetation mixed in the construction materials of the Great Wall, and they discovered that reeds were used in the building materials.
Some of the oldest sections of the Great Wall of China were constructed using reeds and gravel. A team of archaeologists led by Dr. Robert Patalano from the Max Planck Institute for Geoanthropology’s Department of Archaeology analyzed the vegetation used in building many of the walls and watchtowers of the Great Wall in northwest China. Research published in the journal Nature on December 29, 2022, shows that organic building material analysis can provide insight into the local ancient climate and environmental conditions during the time of construction. Furthermore, the team’s method establishes a new foundation for future applications of advanced molecular, biochemistry, and isotope technologies related to the environment, weather, and climate.
Contrary to popular belief, the Great Wall was not built as a single massive construction project, but rather was constructed, repaired, and renovated by nine different Chinese dynasties over a span of 2,300 years. This new research provides additional evidence that some sections of the wall were built, modified, and repaired at different times. Some sections and fortresses date back to the Three Kingdoms period (475-221 BC) and were constructed using bundles of locally available reeds and pieces of wood, mixed with gravel.
The researchers specifically analyzed reed seed specimens, a large plant in the Hermaceae family that grows in temperate and tropical wetlands around the world. The team compared the ancient reeds found within the city walls with modern plant strains in Gansu and Xinjiang, using a combination of chromatography and isotope analysis. Additionally, they utilized techniques such as gas chromatography-mass spectrometry (Py-GC-MS) systems, fat density and distribution analysis, and carbon and nitrogen isotope analysis. Along with electron microscopy scanning techniques, the team found that most of the ancient reed specimens were well-preserved.
Through their analysis of the specimens, the scientists were able to gain insight into and track historical climate and environmental changes along the eastern edge of the Tarim Basin during the Han Dynasty (170 BC). It was found that major hydrological changes due to climate change in the region did not occur until after the Song Dynasty (1160 AD).
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