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Evidence of 4,000-year-old megaflood may support ancient Chinese legend

From Noah's great flood to the legendary kamikaze ("divine winds") that destroyed Kublai Khan's fleet during an attempted invasion of Japan, catastrophic weather events have often played a role in the shaping of legendary tales from around the world.

Now, new geologic evidence unveiled in a recent study published in Science may provide a grain of truth to another ancient legend, a megaflood that helped give rise to China's mythical first dynasty, the Xia dynasty.

Nearly 4,000 years ago, a major landslide sent rocks and debris downhill into the river valley below, creating a giant, earthen dam approximately 660 feet tall, which blocked the flow of the Yellow River. With the forces of water at work, the dam eventually gave way and sent a massive current downstream.

According to National Geographic, through field work and the use of satellite images, the study's researchers were able to find deposits that appeared to be from a lake in the Jishi Gorge River Valley, an area where flood evidence was discovered by lead author Qinglong Wu of China's Peking University in 2007.

In 2009, Wu published a study regarding the evidence he had discovered, which indicated the area once housed a large dam caused by a landslide, but his initial calculations on the size and scope were off.

By re-examining the geologic evidence, Wu and the team discovered that the dam was massive at nearly half of a mile wide, three quarters of a mile long and nearly 660 feet high, according to National Geographic.

Blocked by a massive wall of earth, the team estimated that nearly nine months of river flow sat in wait until it finally broke free, releasing a deluge over the course of hours. According to National Geographic, at the site of Lajia, an area previously studied by Wu, who found sediments washed in by floodwaters, the deluge towered at heights of nearly 131 feet.

Outburst floods are some of the most catastrophic natural events in Earth's history and can drastically change the face of the land. In the United States, eastern Washington state still bears the scars of ice age megafloods that where unleashed as the ice dams failed from glacial lakes near present day Missoula, Montana.

The power of the outburst flood altered the course of the Yellow River and changed the landscape, possibly creating areas of water that lasted for many years after the event, an occurrence that is reflected in the ancient legend.

The occurrence of the megaflood, or the Great Flood of Gun-Yu, around 1920 BCE also coincides China's mythical hero figure, Yu the Great, the tamer of the floods and founder of China's first dynasty - a dynasty that's existence is still debated due to a lack of archaeological evidence.

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According to the legend, Yu's father, Gun, attempted to stop the floods that plagued China for many years. In order to stop the flowing deluge, Gun stole magic soil from heaven to make a dam, which angered the Lord on High, Shangdi. In his anger at the theft, Shangdi ordered Gun to be executed, according to His son, Yu, would eventually complete what his father could not to become a man of great influence throughout the heartland.

In the time following Gun's death, according to legend, the floodwaters still proved to make the land uninhabitable. It was Yu who used labor to build irrigation canals with the aid of great dragons to dredge the riverbed, providing an outlet for the waters and making the land livable. Because of Yu's power over the floods and his upstanding moral character, he gained political influence and founded the Xia dynasty.

"If the great flood really happened, then perhaps it is also likely that the Xia dynasty really existed too. The two are directly tied to each other," study co-author David Cohen of National Taiwan University told National Geographic.