It's not snowing, it's a white desert

Science Times reporter Hu Lijuan

There is a white desert in New Mexico, USA, which is unusual in appearance. Recently, the topic "Did you know that there are white deserts" became a hot search on Weibo.

So, how is the white desert formed? Recently, Kong Weiyuan, an assistant researcher at the Institute of Ecological Protection and Restoration of the Chinese Academy of Forestry, explained the reason. In most of the deserts we see, the main mineral component of sand is quartz, and the trace iron contained in it makes most of the sand yellow. However, the main component of the sand in the white desert in New Mexico, USA, is not quartz, but white gypsum crystal particles. This is because about 100 million years ago, the area was covered by a large saltwater lake, and the gypsum on the surrounding mountains was brought to the lake basin by rainwater. As the lake gradually dried up, a large amount of gypsum precipitated from the lake, leaving behind a thick layer of gypsum crystals. Long-term weathering turned the transparent gypsum crystals into countless small gypsum particles, which were accumulated into white sand dunes under the action of wind, thus forming the white desert.

Kong Weiyuan said that there is a similar white desert in the Farafra Desert in Egypt, and its main component is calcium carbonate formed by marine organisms 40 million years ago.

In addition to white and yellow, deserts can also have different colors. "Some deserts show different colors because they are mixed with other colored substances." Kong Weiyuan explained that the sand in the desert mainly comes from the weathering of rocks around the desert, and the rocks contain colorful minerals. Due to the different mineral compositions of rocks in different regions, colorful deserts are formed in the world.

Parts of the Ulan Buh Desert, one of the eight deserts in my country, are red. "Ulan Buh" is Mongolian, meaning "red bull". Red sandstone containing hematite is distributed in its northwest. The red sand released after the weathering of these sandstones makes the sand dunes in the northwest of the Ulan Buh Desert appear red. In addition, the black desert in Egypt forms black sand dunes because of the mixture of black basalt debris ejected by volcanoes.