Cave gives clues to China's history

"Scientists have found a ancient limestone stalagmite in a cave in northwest China, which offers insights into Asian monsoons and how they may have shaped China's political history.

Certain limestones are made up of plenty of oxygen and carbon traces, which provide a valuable record of past precipitation, temperature and vegetation changes.

In an article published in Science, the researchers say the stalagmite, found in Wanxiang Cave, China, told of strong and weak monsoon periods, which coincided with the rise and fall of several Chinese dynasties.

"For centuries, the Asian monsoon has provided much needed water for crop irrigation. During strong monsoon periods, dynasties such as the Northern Song (960-1127) enjoyed increased rice cultivation and a booming population," the researchers say.

"But weak and consequently dry monsoon periods coincided with the demise of the Tang (618-907), Yuan (1271-1368) and Ming (1368-1644) dynasties."

"Whereas other factors would certainly have affected these chapters of Chinese cultural history, our correlations suggest that climate played a key role," they write.

The 1.18-metre long structure was found in Wanxiang cave, some 1200 metres above sea level between the Qinghai-Tibetan plateau and Chinese Loess plateau in Wudu county in northwestern Gansu province.

The structure grew from 190 to 2003 AD and was discovered in 2003 about 1 kilometre from the cave entrance. (...)"

Full text: Reuters

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