The yellow sand is far above the white clouds
The yellow sand is far above the white clouds
----Sandstorms have been around for a long time
-- -------------------------------------------------- ----------------------------
"Out of the Barrier" by Wang Zhihuan, a poet of the Tang Dynasty, is very popular and can be found in the popular " In "Three Hundred Tang Poems", there are four sentences like this:
The yellow sand is far above the white clouds
An isolated city on the Wanren Mountain
Why should the Qiang flute blame the willows
p>The spring breeze does not pass through Yumen Pass
Yumen Pass is outside Jiayuguan. The closest one in the Yellow River system is Datong River. If this is included, the distance is still about 300 kilometers, and there are also Stretching mountains obstruct it. At Yumen Pass, you can see the Yellow River! How come there is an association with white clouds far above the Yellow River?
Scientists became more serious and discovered this problem. This is Mr. Zhu Kezhen. After research, he believed that this was because Huang Sha was written as Yellow River. The glyphs of "Sha" and "River" when written in cursive are very similar, so it is easy to make mistakes. Later, I heard that this poem was actually found in a newly discovered Tang Dynasty manuscript, and it was clearly the word "sha", which further proved that Mr. Zhu was right.
However, the society does not seem to be interested in Mr. Zhu’s research, and the popular saying is “Yellow River is far above the white clouds”. The seriousness of scientists is indeed a bit "disgusting" sometimes. The beautiful image or imagination that has been circulated for a long time is destroyed by your research, and of course it is unlikely to win people's approval. Mr. Zhu once lamented, "Poets and literary giants have always had the most influence in Chinese thought, but poets and literary giants often ignore facts and consider their own convenience." (Profit and Wrong, 1935)
However, I think Wang Zhihuan pays attention to facts. These four lines of his poems have left us at least two records of natural history. One is that the yellow sand rolls up with white clouds, which means there is a sandstorm; the other is that there are no willows outside Yumen Pass. Of course, the willow he mentioned here refers to the name of the tune played by the Qiang flute, but it can also be understood from a semantic pun. Later, Luo Jialun used "Zuo Gongliu's dawn on Yumen. It's good to block the spring light" to praise Zuo Zongtang for commanding people to plant willows outside Yumen Pass. This obviously came from this.
Zuo Zongtang’s spirit was good, but he could not defeat the laws of nature. After all, willows failed to multiply outside Yumen Pass. However, the coverage formed by Populus euphratica and other plants suitable for growing in desert areas has increased in recent decades. However, due to man-made factors such as land reclamation and overgrazing, it has been damaged and the protection of vegetation has been lost. The ground is even more likely to be blown by strong winds and sand is flying.
Deserts provide the material basis for sandstorms. The exposed ground and drastic changes in temperature cause the rocks here to crumble and disintegrate faster than elsewhere and become debris. In geology, according to the size of their diameter Divided into grades, they are called gravel (larger than 2 mm), sand (2-0.05 mm), and silt (0.05-0.005 mm). Clay (less than 0.005 mm). Coarse gravel will fall when the wind weakens slightly. Only those clay and silt particles can be carried far away by the wind, while fine clay particles can be suspended in the atmosphere for a long time without falling. Beijing residents felt it a few days ago. The dust that arrived also floated over the United States. Therefore, I am afraid that a lot of the sand that falls on the faces of Beijingers comes from local and nearby areas.
Loess belongs to the category of powdery sand. It can be carried out of the desert, but it is not blown far away and accumulates near the desert. The Loess Plateau in my country is distributed close to the desert (please refer to the one on the right) This situation can be seen when the second and third pictures are combined).
Strangely, this phenomenon is rarely seen around deserts in other parts of the world, even in loess. No wonder that more than a century ago, the German geoscientist Ferdinand von Richthofen was amazed when he saw the scenery of my country’s loess areas. The following is what he did for the loess riverbank near Huaiqing Prefecture (today’s Qinyang) sketch. (According to Richthofen: "China", Volume 1, Page 60, published in Berlin in 1877)
Richthofen reported China's loess to the world for the first time, and proposed that the loess was mainly wind belt The term for the accumulation of debris. Scholars then argued heatedly about the origin of this loess. Some people disagreed with Richthofen's explanation and believed that it was probably the product of in-situ weathering of rocks, or the movement of water, etc.
Nowadays, many geoscientists still prefer the "fengcheng theory". Such a huge accumulation of loess is a unique phenomenon in China. The correct answer can only be found based on the history of this land.
I agree with the view of my teacher Mr. Wang Yinzhi (1911-1976): He said in his 1957 book "Chinese Geological History Materials": "This issue (referring to the cause of loess) has been around for nearly a hundred years. It still seems to be a problem. Judging from our country's historical records, the problem should have been solved long ago. In 1287, there was a heavy rain of seven or eight feet like this. "This solved the problem of the origin of loess." Mr. Wang found it 107 times in ancient Chinese books.
And it was discovered that the number of rains and soils recorded in each period varied greatly, which may reflect the dryness and wetness of the climate at that time. There was more rain and less chance of sand and soil being blown up in large quantities.
The "rain and soil" in Chinese historical records, according to its description, is today's sandstorm: the sky is filled with yellow mist, and sand and soil fall from the sky like rain. The location of rain soil is mainly in and near loess areas, which is also evidence. In 1287, the twenty-fourth year of the Yuan Dynasty, "it rained and soiled for seven days and nights in Outer Mongolia, but no cattle or livestock died" (Yuan History/Five Elements Chronicles). Even livestock as big as cattle were buried by the falling soil. One can imagine the scale of this sandstorm. The ancients regarded such things as strange catastrophic phenomena. At that time, people believed in the "influence of heaven and man". For example, the natural history compiled by Zhang Hua of the Jin Dynasty recorded: "During the time of Xia Jie, the Changye Palace was in a deep valley, where men and women lived together. They did not come out for ten days to listen to government affairs, and the sky was full of strong winds. "Sands will fill this empty valley overnight." The warning message is very clear. Therefore, some major events will also be recorded in official history.
Looking at the long history of the earth, sandstorms have appeared in the land now known as China for a long time. Otherwise, why come here on the Loess Plateau? The thickness of the loess layer ranges from tens of meters to nearly 400 meters at most. Moreover, there are loess accumulations on the tops of many mountains in North China such as Wutai Mountain and Taihang Mountain.