Legend has it that hidden under the waves of the Atlantic Ocean was a once highly civilized state called Atlantis. On the other side of the world, a similar tale persists that an ancient city is buried deep in a lake in Yunnan, a border province in Southwest China.

But unlike the mythical tale of Atlantis, the submerged secret in Fuxian Lake near Kunming, capital city of Yunnan, may be a reality, as divers continue finding proof of its existence.

Eight years ago, a local diver named Geng Wei saw a slew of large flat rocks scattered under the water 300 metres away from the eastern bank of Fuxian Lake.

"These boulders have regular shape, each with more than 1.4 square metres. Many of them are broken into half, with clear clefts," said the swarthy man, who led a large exploration into the lake recently.

The seven-day underwater expedition that started last Friday and ends today is a second one at the lake in the past five years. The first exploration in 2001 was prompted after Geng submitted his discoveries to the local government.

That venture was broadcast live by China Central Television (CCTV), and divers found a stone wall and a shard of pottery.

The shard was later proved to date back to the Han Dynasty (BC 206BC-AD220), leading local archaeologists to believe the underwater relics were at least 1,800 years old. Some of them even assumed that what was actually beneath the water was Yuyuan, an ancient city that disappeared mysteriously from historical documents.

Old books have shown that there was once a city called Yuyuan to the north of Fuxian Lake, which was never mentioned after the Northern and Southern Dynasties (AD420-581).

These affirmations have led to great challenges upon new contradictory findings in the recent exploration.

Interesting signs and patterns

Last Friday, divers used an underwater camera to show experts their latest discovery: Three notches, each 1.2 meters long and 45 centimeters wide, on a moss-covered square rock, which made up a shape that looked like "IY."

The notches are not natural, therefore supporting the hypothesis that the stone relics were once part of man-made buildings, according to Li Kunsheng, director of the Archaeology Research Centre of Yunnan University.

"It must be a sign ancient people used to record something," added Li, who has kept his eye on the mystery for years.

More signs and patterns were discovered on the huge underwater rocks 20 meters under the water's surface on the following day, including some embossed signs, a carved sign consisting of a circle and a straight line, and what looked like a carved human face.

Liu Qingzhu, director of the Institute of Archaeology at the Chinese Academy of Social Sciences, was particularly drawn to the parallel signs of circle and straight line.

"If we know how this rock was placed originally, we could better tell what this sign conveyed," said the archaeologist, who was also present at the first Fuxian Lake exploration five years ago.

He explained that the sign of the circle was frequently used by ancient people to represent the sun.

"If the original sign had the circle above the line, it no doubt referred to the morning sun," Liu said.

However, two days after this discovery, divers did find "the sun" on other rocks.

Two patterns, both of straight lines around a circle, were found on the same rock on Tuesday. One pattern has four straight lines, while the other has eight straight lines of different lengths, surrounding the circle.

Li said the patterns probably meant to represent the sun and its light.

The emergence of the signs, however, disproves the previous hypothesis that the relics are 1,800 years old, two experts said.

"In the Han Dynasty, Chinese characters were already popular. Why would people bother to use more ancient signs in their buildings instead of chiselling out characters?" Liu questioned.

"The only explanation is that the construction was much older than we previously thought."

If that is true, the age of the relics could be about 4,000 years old.

But, the scientist was still puzzled by his own conclusion, as "there is little possibility that people 4,000 years ago could build such large stone constructions."

The underwater building relics, as sonar detected, scatter in an area of 2.4 square kilometers, more than double the size of the city of Pompeii, which was swallowed by volcanic lava from Mount Vesuvius.

"The only ancient stone city of that age we have found in Inner Mongolia is much smaller than this. It is illogical that Yunnan had the same old city with a much bigger size, let alone that the province was less civilized than the northern area," Liu said.

"Also, ancient people in this area had no tradition of making rock buildings. They used to construct with bamboo, wood or mud."

Divers also discovered a pattern that looked like a stretched human face on a flat rock. With two long "eyebrows," a small "nose" and a corrugated "mouth," the pattern looks only partially man-made, Liu said.

"It seems that someone produced it from some natural scratches," he added.

The senior archaeologist also cast doubt on its form, saying that the "flat and disproportionate" face may be of an animal instead of a human.

In theory, less civilized people drew pictures to depict real things. Only in modern times did individuals add personal imagination to portraits to express their unique style or ideas, Liu explained.

"The pattern looks more like something from Pablo Picasso than ancient Chinese," Liu joked.

Near this rock, there was another interesting discovery of a flat rock with many holes.

There are five holes lined in a curve on one rock, about 15 to 20 centimeters apart.

"They have smooth walls and flat bottoms, suggesting they are human-made," Geng said. "The two slates could have been integral."

Though Li conjectured the holes might be related to sacrifice, Liu was reluctant to draw a conclusion.

"If they were used to hold remains, how could people keep the ashes? If they were used to hold flags, they could not have had different sizes," Liu said.

"I never saw anything like this before. We need more evidence to make a judgment."

An ancient city?

Divers all said that the layout of the underwater relics suggests some stone buildings had collapsed.

"Over an edge of stone piles, the water suddenly expanded before my eyes. A collapsed but still discernable stone staircase emerged under my body, slanting into deep water," said Zhao Yahui, a reporter with People's Daily who tried a 30-minute dive on the second day.

He said on every two or three rocks were signs and patterns.

There is enough evidence to prove that there are old buildings under the lake, archaeologists said.

But because preliminary analyses about the signs and patterns oppose the previous inference that the underwater construction was built 1,800 years ago, it could rule out the notion that the relics were a part of Yuyuan.

Nonetheless, some local archaeologists argued that Yunnan had a laggard civilization history compared to hinterland, so it is still possible that Chinese characters were not that popular in this place during that time.

Is it something older?

The stone structure contradicts both assumptions, but supports a more wild theory put forward by Zhang Xinning, a senior local archaeologist.

According to Zhang, the relics may only be several hundred years old, when the place "had lots of stone buildings."

"There is a question we need to ask before jumping to a conclusion," he said.

"Did the relics result from one collapse or several collapses in different time?"

Sitting right on an earthquake-intensive belt, the Fuxian Lake area may have swallowed more than one building more than once, Zhang said.

All these questions remain puzzles since "no cogent evidence, such as containers or instruments, were found," Geng said.

Liu said it is hard to imagine that it was a city, because "not a single trace of human activities was left." But he added that water flow must have flushed some evidence somewhere else in the huge lake.

Also, to facilitate further examination, divers have not been allowed to move the rocks until they label them and have a specific map of their layout.

"Maybe something is hiding beneath these rocks," said Geng, who has spent these years working together with other local divers fixing labels and indicators on the relics.

He said the seven-day exploration only targets a small area of the relics, about 800 square meters wide and less than 20 meters deep.

A robot was dispatched on the third day to explore a deeper area, but nothing new was found.

"It may take us no less than 10 years to conduct such a huge underwater archaeological investigation. It is far more difficult than doing on the land. More difficult for the fact that we archaeologists cannot dive, and divers do not have the same knowledge," Liu said.

(China Daily June 22, 2006)