Collapse of ancient Liangzhu culture caused by climate change

Date:
November 24, 2021
Source:
University of Innsbruck
Summary:
Referred to as 'China's Venice of the Stone Age', the Liangzhu
excavation site in eastern China is considered one of the most
significant testimonies of early Chinese advanced civilization. More
than 5000 years ago, the city already had an elaborate water
management system. Until now, it has been controversial what led
to the sudden collapse. Massive flooding triggered by anomalously
intense monsoon rains caused the collapse, as geologists and
climate researchers have now shown.



FULL STORY ========================================================================== Referred to as "China's Venice of the Stone Age", the Liangzhu excavation
site in eastern China is considered one of the most significant
testimonies of early Chinese advanced civilisation. More than 5000 years
ago, the city already had an elaborate water management system. Until
now, it has been controversial what led to the sudden collapse. Massive flooding triggered by anomalously intense monsoon rains caused the
collapse, as an international team with Innsbruck geologist and climate researcher Christoph Spo"tl has now shown in the journal Science Advances.


==========================================================================
In the Yangtze Delta, about 160 kilometres southwest of Shanghai, the archeological ruins of Liangzhu City are located. There, a highly advanced culture blossomed about 5300 years ago, which is considered to be one
of the earliest proofs of monumental water culture. The oldest evidence
of large hydraulic engineering structures in China originates from this
late Neolithic cultural site. The walled city had a complex system of
navigable canals, dams and water reservoirs. This system made it possible
to cultivate very large agricultural areas throughout the year. In the
history of human civilisation, this is one of the first examples of
highly developed communities based on a water infrastructure. Metals,
however, were still unknown in this culture.

Thousands of elaborately crafted jade burial objects were found during excavations. Long undiscovered and underestimated in its historical significance, the archaeological site is now considered a well-preserved
record of Chinese civilisation dating back more than 5000 years. Liangzhu
was declared a UNESCO World Heritage Site in 2019. However, the advanced civilisation of this city, which was inhabited for almost 1000 years,
came to an abrupt end.

Until today, it remains controversial what caused it. "A thin layer
of clay was found on the preserved ruins, which points to a possible
connection between the demise of the advanced civilisation and floods
of the Yangtze River or floods from the East China Sea. No evidence
could be found for human causes such as warlike conflicts," explains
Christoph Spo"tl, head of the Quaternary Research Group at the Department
of Geology. "However, no clear conclusions on the cause were possible
from the mud layer itself." Dripstones store the answer Caves and
their deposits, such as dripstones, are among the most important climate archives that exist. They allow the reconstruction of climatic conditions
above the caves up to several 100,000 years into the past. Since it is
still not clear what caused the sudden collapse of the Liangzhu culture,
the research team searched for suitable archives in order to investigate
a possible climatic cause of this collapse. Geologist Haiwei Zhang from
Xi'an Jiaotong University in Xi'an, who spent a year at the University of Innsbruck as a visiting researcher in 2017, took samples of stalagmites
from the two caves Shennong and Jiulong, which are located southwest of
the excavation site.

"These caves have been well explored for years. They are located in the
same area affected by the Southeast Asian monsoon as the Yangtze delta
and their stalagmites provide a precise insight into the time of the
collapse of the Liangzhu culture, which, according to archaeological
findings, happened about 4300 years ago," Spo"tl explains. Data from
the stalagmites show that between 4345 and 4324 years ago there was a
period of extremely high precipitation.

Evidence for this was provided by the isotope records of carbon, which
were measured at the University of Innsbruck. The precise dating was
done by uranium-thorium analyses at Xi'an Jiaotong University, whose measurement accuracy is +/- 30 years. "This is amazingly precise in light
of the temporal dimension," says the geologist. "The massive monsoon rains probably led to such severe flooding of the Yangtze and its branches
that even the sophisticated dams and canals could no longer withstand
these masses of water, destroying Liangzhu City and forcing people to
flee." The very humid climatic conditions continued intermittently for
another 300 years, as the geologists show from the cave data.

========================================================================== Story Source: Materials provided by University_of_Innsbruck. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Haiwei Zhang, Hai Cheng, Ashish Sinha, Christoph Spo"tl, Yanjun
Cai et
al. Collapse of the Liangzhu and other Neolithic cultures in the
lower Yangtze region in response to climate change. Sci. Adv.,
2021 DOI: 10.1126/sciadv.abi9275 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/11/211124153813.htm

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