Fourteen skeletons of victims killed by an earthquake nearly 4000 years ago in a village called Lajia, sometimes called "the Asian Pompeii." The earthquake is thought to also have triggered a massive river flood. Image credit: Cai Linhai

 

Along the banks of the Yellow River in northwest China’s Qinghai province, scientists have discovered evidence of one of the most cataclysmic floods on Earth in the past 10,000 years.

This disaster, which occurred nearly 4000 years ago, might match the Great Flood of Chinese legends. Historians have debated whether this flood was merely a myth, part of a founding story to bolster the legitimacy of China’s dynasties. But the findings published in the journal Science today, August 4, offer the first physical evidence of such a catastrophe.

The scope of the flood that the researchers describe is difficult to imagine. According to their reconstructions, a wall of water some 427 feet high—one-third of the height of the Empire State Building—burst through a natural dam in the Jishi Gorge and then rushed downstream at a rate of 300,000–500,000 cubic meters per second. After the dam broke, the Yellow River rose 125 feet above its normal level.

“To put that into perspective, that's roughly equivalent to the largest flood ever measured on the Amazon river, the world's largest river,” study co-author Darryl Granger, a geologist at Purdue University in Indiana, told reporters during a press conference Wednesday. “It's among the largest known floods to have happened on Earth during the past 10,000 years. And it's more than 500 times larger than a flood we might expect on the Yellow River from a massive rainfall."

Jishi Gorge today, upstream from the location of the ancient landslide dam. Image credit: Wu Qinglong

The researchers, led by Wu Qinglong, a professor of geography at Nanjing Normal University, mapped distinctive flood sediments along both sides of the river and outlined a disaster scenario. They think an earthquake triggered a massive rock slide that dammed the river. Then, over the course of six to nine months, a lake filled up behind the 600-foot-high dam. When this natural dam overtopped and then failed, an outburst flood occurred.

For hundreds of miles downstream, water inundated Neolithic villages like Lajia, sometimes called the "Asian Pompeii." Just before the flood, Lajia had been destroyed in an earthquake—the same one that triggered the dam-forming rock slide. Archaeologists digging through the rubble there have discovered bodies and artifacts frozen in time, such as the world’s oldest bowl of noodles.

The earthquake may have lasted just one minute, but its impact was enormous. Image credit: Wu Qinglong

 

“The earthquake-landslide dam-outburst flood scenario makes sense,” said James O’Connor, a geologist with the U.S. Geological Service who has researched the world's largest floods [PDF]. He wasn’t involved in the current study. “Similar historical and prehistorical events have been documented in most mountainous regions of the world, although this one seems to have been one of the larger ones.”

As O’Connor noted, more work is needed to fully understand potential downstream effects. But more recent history has shown that similar outburst floods can be devastating. A landslide dam outburst flood on China’s Dadu River in 1786 is believed to have killed more than 100,000 people.

The flood could be the disastrous Yellow River flood described in Chinese sources from the mid- to late first millennium BCE, such as the Book of Documents and the Records of the Grand Historian. According to those traditions, a legendary hero, Yu the Great, received a divine mandate that allowed him to tame the flood waters. After he led a large-scale dredging operation, Yu established the Xia dynasty, the purported first dynasty of China, bringing political order out of the chaos left behind by the devastating natural disaster.

The reliability of this origin story has been debated, as many parts of these Chinese historiographies are clearly legendary. Take, for example, the story of Yu’s conception. According to archaeologist Robert Murowchick, director of the International Center for East Asian Archaeology and Cultural History at Boston University, ancient sources say that either Yu’s mother became pregnant by eating grains of Job’s Tears or that Yu’s father, Gun, was executed and turned to stone after he failed to stem the flood with an “ever-swelling mold,” and when someone cut the stone open, out came Yu.

The variable timelines for the start of the Xia dynasty according to traditional Chinese culture, the Xia-Shang-Zhou Chronology Project, and the flood newly identified and dated by Wu et al. Image credit: Carla Schaffer/AAAS

If the real flood described in the new Science paper is truly the Great Flood of those ancient historiographies, then the Xia dynasty might have been established more recently than previously believed. The start of the first dynasty has been dated to 2200 BCE, and sometimes as early as 2700 BCE. (Still other scholars have argued that this dynasty never existed because no archaeological evidence associated with it has been found.) Based on radiocarbon dates obtained from three skeletons of children who were killed in the collapse of a house at Lajia during the earthquake, the researchers estimate that the resulting flood took place around 1920 BCE. This time period also roughly marks the start of the Bronze Age in China, when the first urban societies emerged. Altogether, this suggests there could be some truth to the stories about Yu’s heroic exploits—though no archaeological evidence of post-flood dredging has been discovered yet.

“I think it is an intriguing example of how good geological detective work can provide evidence that can help to shed light on the rich textual histories that we have from ancient China,” Murowchick, who wasn’t involved in the study, told mental_floss. He noted, however, that the study’s authors have not yet proven that the stories of Yu and his flood-stemming deeds could be taken as fact.

“I think a parallel can be drawn with efforts to find geological evidence of the Biblical flood,” Murowchick said. “If concrete geological evidence were found in the appropriate location of the Near East, it would help us to understand the facts of a particular flood event, but it doesn’t necessarily prove that stories of Noah and his Ark are true.”

Similarly, O’Connor said this may be a prime example of the flood stories that underpin many legends and even religions: “Although we can never know for sure for many of these stories, there's something immensely satisfying, at least to me, in understanding how human history, cultural traditions, and belief systems may relate to specific natural phenomena.”