In Dunhuang in northwest my country, there is a famous tourist attraction-Mingsha Mountain.
For those who have just arrived at the foot of the mountain, the first thing they are attracted to is the appearance of Mingsha Mountain: the majestic and towering mountain is entirely made of sand. Looking from a distance, the mountain looks like A piece of beautiful jade covered with white gauze, smooth and delicate, light and sparkling, without any rugged rocks or trees. Under the sunlight, the sand emits a faint yellow light, giving people a brilliant feeling.
In addition to the beautiful and unique appearance of Mingsha Mountain, what is even more attractive is its sound of sand. If you push your way up the mountain and then slide down the sand hill like a child on a slide, the sand beneath you will begin to chirp. If you control the speed and slide down slowly, you will hear the sound of Chinese silk and bamboo, like a bow grazing slowly on the strings, or like your fingers lightly plucking the strings; if you slide faster, the sound will be It's like a saxophone is playing, sometimes dull, sometimes elegant; if there are many people sliding down together, the sound of the sand will sound like a huge organ playing, very majestic and solemn.
Mingsha Mountain, named after the sand grains that sing, has attracted many tourists since ancient times. While people appreciate the sound of sand, they often ask the same question: Why do sand grains play beautiful music? Local people often answer this with a legend: Mingsha Mountain was the incarnation of a girl who loved to play the pipa. The girl's lover took a team of camels to the other side of the desert and never showed up again. The girl waited here for a long time. It turned into a mountain of sand. When someone came, the girl would pluck the silk string and tell the misery in her heart.
The legend is certainly moving, but it seems a bit absurd if it can be used as a substitute for scientific explanation of this mystery. Scientists have their own explanation for this.
Some people believe that when the sand grains slide, the gaps between the sand grains sometimes expand, sometimes shrink, and are constantly changing. At the same time, the air sometimes enters the gaps and sometimes is squeezed out of the gaps. , thus producing vibration and sound.
Some people believe that there are a large number of quartz sand grains in the singing sand. Quartz sand grains are very hard. When they are heated by the sun, if people and horses walk on it, the sand grains will rub and make noise. Sometimes, as long as the wind blows, it will make it chirp. In recent years, some experts have given a more in-depth explanation of the chirping of quartz sand. They believe that because quartz crystal is very sensitive to pressure, it will generate electricity, produce reciprocating expansion and contraction, and cause vibration. The greater the vibration, the higher the voltage; the higher the voltage, the greater the vibration, resulting in sound.
Some people also believe that the sound of sand is caused by a moist sand layer under the sand mountain. When the dry sand above slides down the slope, the vibration waves of the dry sand are transmitted to the moist layer, causing ***Ming, make a sound. These people said that the geographical characteristics of Mingsha Mountain can be confirmed: at the foot of Mingsha Mountain is a green Crescent Spring, which is probably the spring that caused Mingsha. The singing sand in other places seems to confirm this statement.
There is a sand mountain called Shapotou in Zhongwei County, Ningxia, my country, located on the edge of the Yellow River. The sand mountain is about 100 meters high. The middle part of the slope is concave and has many springs. As people rolled down the hill, the sand rumbled loudly, like a line of cars passing by in the distance. There is also a ringing sand mountain in Barkol, Xinjiang. The sand mountain is more than 200 meters high. There is a spring at the foot of the mountain, and the spring water flows out to form a pool.
Some famous foreign sand sounds are mostly related to water. For example, the Riga seaside in Latvia, the Lena River Valley in Russia, and the shores of Lake Baikal all have vast expanses of sounding sand. When people step on it, their feet often make a sudden cry, which can make people startle. There is a sand dune 800 meters long and 18 meters wide on the coastal area of ??Kauai Island, Hawaii. If people walk on the sand dune, they can hear the clear barking of dogs from the sand. The drier the sand, the louder the sound. When many people are walking, the sound is like a pack of dogs barking.
In addition, some people have suggested that the sound box of Xiangsha is not underground, but in the air above the ground. The most important condition for seaside sound sand is that there must be clean water to continuously wash it. In 1952, residents of the city of Nikopol-on-Lapi, a tributary of the Dnieper River in the Soviet Union, had an unforgettable experience. Residents are well-known to the fact that the beach along the Lapi River makes noises, but the cry after the rain that year was the clearest and strangest: when people walked on the beach, the beach emitted a sound similar to gas coming out of a car tire. The whistling sound produced.
As soon as the footsteps stopped, everything was silent for a moment, but as long as the footsteps moved slightly, the howling sound would come out again.
In fact, people have noticed the phenomenon of sand grains singing for a long time. There is a piece of Yinken Xiangsha beside a river in Dalat Banner, Inner Mongolia, my country. The word "Yinken" means "eternal" in Mongolian, which shows that countless generations of people have already noticed this mysterious sand. However, there is still no definite explanation as to why the sand grains make the noise. Perhaps, all the above-mentioned opinions are reasonable. Perhaps, the sound of sand grains in some places is the result of the combined effect of some of the above-mentioned opinions.