How to explain the rice field strange circle?

Underground karst caves lead to the collapse of rice fields.

The mysterious "crop circle" phenomenon once attracted the attention of many curious people. Some people suspected that it was the trace left by aliens on the earth, and later some people took the initiative to "admit" that it was a "prank." On June 28th last year, in a rice field in a certain place in Fujian, some holes with different arrangements and sizes, similar to crop circles, suddenly appeared, and all kinds of speculations were circulated among the people for a time.

At the foot of the scenic Wuyi Mountain, the Minjiang River winds through Yuankeng Town, Shunchang County, Fujian Province. Farmers who have lived here for generations have worked at sunrise every day and rested at sunset, and their lives are as calm as water. On June 28th, 2004, a strange thing I have never heard of broke the peace here.

In the rice field where villagers lived for nearly a hundred years, strange holes with unknown reasons suddenly appeared.

Overnight, four strange holes of different sizes and bottomless suddenly appeared in several rice fields that the villagers were still cultivating yesterday. It is as big as half a basketball court and as small as a small dining table for a family of four.

What is even more strange is that these strange caves, which are hundreds of meters apart, will grow and change by themselves. The next day, when the villagers came to the field again, they saw that these strange caves were getting bigger and deeper and filled with water. This sudden change made the villagers feel uneasy.

What happened to the strange hole in the rice field? The villagers were at a loss and suspicion began to spread in the village.

Fortunately, there is an old geologist Xiao Lian who has worked in the geological department for decades in Yuankeng Town. He is 77 years old this year. After retirement, he still can't leave his old job. He often travels across mountains and rivers to find his favorite ore. Xiao Lao knows the local geological conditions like the back of his hand. He was very interested in this strange pit and began to investigate.

Some villagers speculated that it was related to local road blasting. 50 meters away from the strange hole in the rice field, a Beijing-Fuzhou expressway connecting Beijing to Fuzhou is under intense construction. Because building roads requires cannon, which will inevitably cause local ground vibration, the villagers naturally associate strange holes in paddy fields with building roads.

Is there a necessary connection between strange holes in rice fields and road construction? Will the construction of expressway be the inducement?

According to the analysis of experts from the northern Fujian geological team, the Jingfu Expressway is a small-area mountain blasting, which will not have much impact on the local geological conditions in theory. In addition, if the expressway is built, the geological team should send relevant technicians to conduct a detailed survey of this area in advance. If it had been found that the stratum in this place was unstable and there was something underground, the road would not have been built from here. Therefore, it seems a little far-fetched to link the potholes collapsed on the ground with the construction of Beijing-Fuzhou Expressway.

The cause of rice field collapse caused by expressway construction has been ruled out, so what caused the collapse? The investigation found that it hasn't rained here since last autumn, and it has been dry for several months in a row. Is it the special climate that causes the strange caves under the rice fields? Not long ago, there were two landslides in Yuankeng Town.

Xiao Lian said: "The landslide phenomenon is because the ground cracked after a long drought, just in time for the arrival of Typhoon No.28 a few days ago. Due to the influence of rain, water poured in from the cracks, and the soil was hard and loose, so landslides occurred. "

Will the recent two landslides cause strange holes in the ground collapse of rice fields?

After careful analysis, Tian Qifa, a geological expert, thinks that there should be no direct connection between strange caves in rice fields and landslides. According to field investigation, the scale of landslide is not very large, and the landslide may not be in limestone stratum.

When experts say limestone stratum, they actually mean something called interlayer geological stratum. Sandwich rock, as the name implies, is like a sandwich, with two pieces of bread on both sides and sausage, ham and vegetables in the middle. This stratum is composed of sandstone, and the upper and lower textures are hard, while the middle part of the stratum is soft, so the middle stratum is particularly prone to weathering.

Therefore, under some special conditions, this kind of rock stratum is easy to fall off. As a result, a large area of landslide appeared. In addition, landslides may also lead to ground collapse. However, the scale of ground collapse caused by this underground landslide is relatively large, and it must be a relatively large hole exposed outside, not a very small hole like Yuankeng Town.

Obviously, the strange hole in the rice field has nothing to do with the underground collapse. So how did this happen?

Due to the natural geological structure, there are many limestone deposits in Yuankeng Town. As a result, several cement plants have chosen to build factories near Yuankeng Town, and there is a cement plant near the rice field. Although the scale is not large, it needs quarrying to make cement. Is it the fault of quarrying in rice fields? In order to further verify, the reporter found the manager of Yuankeng Lime Mine to understand the situation.

In Wen's opinion, because there are more limestone mines in Yuankeng, the quarrying capacity of this cement plant is less. Now they are not mining underground, but mining on the surface, which should not cause the ground to collapse.

In the interview, we found that this cement factory is only 50 meters away from the place where the rice field collapsed, and the workers who work here every day are also in jeopardy. Are you worried that the cement plant will close down soon?

Experts from the Northern Fujian Geological Team believe that the balance between the cement plant and the paddy field has been going on for a long time, and the collapse of the paddy field is not induced by human factors such as quarrying. Therefore, the occurrence of rice field collapse has nothing to do with this cement plant.

Now the phenomenon of rice field collapse continues, and the villagers are very worried.

In the interview, the number of strange holes in rice fields collapsed in Yuankeng Town has increased to 19, and no one knows when the 20th and 2nd1strange holes will appear.

Just when everyone was at a loss, a new geological situation was discovered. 1986, a cement factory plans to build a factory in Yuankeng Town. After investigation, experts found that there were geological problems here and made a detailed investigation report. It is reported that there are large and small caves superimposed on each other in the rock strata of this place.

With this premise, the mystery of rice field collapse is expected to be solved. Because limestone contains a lot of calcium carbonate, it is easily dissolved in acidic substances.

Under natural conditions, if carbon dioxide is dissolved in water, it will form acidic substances. This will cause considerable damage to the rock formation.

When rain falls from the air, they will get a little carbon dioxide in the atmosphere, but this amount is very small and can't dissolve rocks at all. Microorganisms or plant roots on the surface will produce a lot of carbon dioxide, which will be dissolved when water flows through the soil. With the help of carbon dioxide, limestone is slowly dissolved by water.

Karst makes many cracks in limestone layer wider and wider, and a large amount of rainwater collects underground, dissolving limestone constantly and forming underground rivers. The underground river keeps taking away rocks and dissolving them. Waterways are constantly expanding underground, and after thousands of years, even hundreds of thousands to millions of years of long geological years, caves with different shapes have been formed in rock formations. In this way, will the strange cave of rice field collapse be on karst landform?

The mystery of the strange hole in the rice field has finally been solved, and the solution is being studied.

The strata distributed in Yuankeng Town are limestone areas deposited 20,000 years ago. Due to the long-term karstification under the paddy field, the cracks in the rock at the top of the limestone cave are wider and wider, and the irrigation water in the paddy field seeps into the cave, and more and more water is accumulated. Under the long-term dissolution of water, the rock at the top of the cave becomes thinner and thinner. Finally, it couldn't bear the pressure and collapsed in the cave.

The town government warned the villagers of these hidden dangers. Today, the collapse continues, and there are many cracks around the rice fields. At present, experts are studying the solution, whether to backfill or adopt other methods.