中國是一個幅員遼闊的國家，陸地總面積大約為960萬平方公里，接近於整個歐洲的總面積。

在中國境內有著一個很大很大的大沙漠，它就是塔克拉瑪干大沙漠，它的總面積達到了33萬平方公里，作為一個沙漠，這個規模的確足夠驚人了，但在世界上還有著比它大得多的沙漠，那就是著名的撒哈拉大沙漠，撒哈拉大沙漠位於非洲北部地區，是世界上整體範圍最大的沙漠，幾乎佔據了整個北非，它的面積更是達到了驚人的940萬平方公里，接近於中國的陸地總面積，很難想像，如此巨大的沙漠是從何而來的呢？

其實，撒哈拉大沙漠的範圍雖然達到了940萬平方公里，但並不是說在940萬平方公里的範圍內都是一望無際的沙丘，如果是這樣，那也太過恐怖了。事實上撒哈拉大沙漠的沙丘覆蓋率並不是特別高，大概只有15%左右。

The sand dunes of the Sahara Desert are only about 15% covered, and they are not continuous, the areas covered by the dunes are individual individuals, if we compare the Sahara Desert to a leopard, then the area covered by the dunes is like the patches on the leopard's body.

In the Sahara Desert, each area covered by sand dunes has its own characteristics, and the thickness is also different. In the Sahara Desert, the sand in some areas may be only a few centimeters thick, while in others the depth of the dunes can reach more than 300 meters, although the height of these dunes is not static, and even their location can change from time to time. The sand has a good flow and as soon as the wind blows, the dunes start to move. The sand dunes, which were just hundreds of meters high, could become a flat land in an instant, and a new sand dune was accidentally piled up in a place that was just a flat river.

In film and television works, we often see people trapped in the desert, unable to find a way out for a long time, and finally die of thirst, this description is very realistic.

If we don't have a tool that can show us the way, it will be very difficult to escape in the desert, because the shape and position of the dunes will change, and the speed and frequency of change will be very fast, so it is impossible to identify where we have walked and where we have to go to get out smoothly.

Why is there so much sand in the desert, and how did such a huge desert like the Sahara Desert come to be? Obviously, the Sahara Desert is not a product of the earth, and in fact in the near past, the Sahara was not a desert, but a collection of forests, grasslands and oases. There is certainly a basis for this, based on ancient rock art found by archaeologists in the Sahara.

The ancient petroglyphs found by archaeologists in the Sahara region depict a large number of running animals, and these animals are not the desert animals we are familiar with, but buffalo, hippos and elephants, which means that in the near past, these animals used to live in this area, and these animals are obviously inseparable from water, which can prove that this was once a place with abundant water resources and fertile water and grass.

那麼是什麼原因導致了撒哈拉地區的沙漠化呢？在1000萬年以前，地球的板塊與現在並不相同，那個時期這裡有兩塊古老的大陸，一塊是位於北方的勞亞古路，另一塊則是位於南方的岡瓦納古路，在這兩塊大陸之間存在著一片海洋，我們稱之為“特提斯海”。現而今，特提斯海已經不復存在了，但是它還遺留下了一片殘存的海域，我們就將這片海域稱之為“地中海”。而特提斯海的消失與撒哈拉沙漠的形成有著直接的關係。

Because of the continuous contraction of the Tethys Sea, the summer monsoon in the Sahara region gradually weakened, so the climate in this region became more and more arid, drought is the breeding ground for deserts, and slowly, the land gradually deserted, and the world's largest desert was born.

Now, when we dig up the sand dunes, all we see is a desert of desert, no one would think that this place was once a dense forest and vast grassland, but as long as we continue to explore downward, we can still find clues, because in the Sahara Desert there is a large amount of groundwater, and it is very widely distributed, and some can even be called underground lakes. Some aquifers have been exploited, such as the Nubian Aquifer in Libya, which can meet the Libyan people's demand for water resources within 100 years. Although the formation of the Sahara Desert is caused by the movement of tectonic plates, in many parts of the world today, some lands are facing the doom of gradual desertification due to various human factors, and each of us should be vigilant to reduce the desertification caused by human factors, after all, we are not camels, and we do not have the ability to survive in the desert.