VOA科学技术2024--Researchers Uncover ‘Secrets’ of African Sand Dune

Researchers Uncover ‘Secrets’ of African Sand Dune¹

　　Researchers have used radar² and other technologies to study a large "star" sand dune in eastern Morocco. The team said it was able to capture detailed³ data on how these dunes⁴ form and develop.

　　A star dune is named after its shape because it can look like a star when seen from above. These structures are very large and have a hill, or peak, at the top. They have large masses, called arms, spreading out from the peak. Star dunes are shaped by wind and other conditions in the environment.

　　Star dunes are common in deserts and can be found in Africa, the Middle East, China and North America. But scientists say, although there are a lot of star dunes, the formations have not been studied very much so far.

　　The new study – believed to be the first of its kind – was led by two British researchers. It examines a large star dune in the Sahara Desert's Erg Chebbi sand sea in Morocco. The research results recently appeared in the publication Scientific Reports.

　　The scientists said the star dune rises 100 meters above surrounding dunes and is 700 meters wide. The structure contains an estimated five-and-a-half metric tons of sand.

　　The researchers used radar that can "see" underground to look at different elements within the star dune. The science instruments that were used are designed to map all layers within the dunes. They also used a method called luminescence dating to study the age of the dune. This method uses minerals in the sand to estimate when they last received sunlight in an attempt to guess the age of the dune.

　　Geoff Duller is a professor of geography and earth sciences at Britain's Aberystwyth University. He said in a statement the new technology had finally made it possible to study these large dunes. "It's only because of new technology that we can start to uncover their secrets," Duller said.

　　The researchers estimated the oldest parts of the base of the star dune are about 13,000 years old. And the dune is moving across the desert at a rate of about 50 centimeters a year. The team noted⁵ the star dune experienced the most growth during the past 1,000 years.

　　Star dunes make up just 10 percent of all dunes in Earth's deserts. They have also been observed on Mars and on Saturn's moon Titan.

　　Earth's largest star dunes are found in western China's Badain Jaran desert. Star dunes also are found in places including the Namib Sand Sea in Namibia, large sand seas in Algeria and Rub' al Khali in Saudi Arabia. In North America, Great Sand Dunes National Park in Colorado contains a series of them.

　　"I first encountered star dunes in Namibia 20 years ago," Duller told Reuters news agency. He added that he still has clear memories of being surprised at the size and beauty of the first sand dunes he saw. "I have a vivid memory of the long climb to the top, struggling up very loose sand in the heat of the day."

　　Words in This Story

　　dune – n. a hill of sand in a desert

　　luminescence – n. the giving out of light by a substance

　　vivid – adj. clear or strong

1 dune   

n.(由风吹积而成的)沙丘

参考例句：

• The sand massed to form a dune.沙积集起来成了沙丘。
• Cute Jim sat on the dune eating a prune in June.可爱的吉姆在六月天坐在沙丘上吃着话梅。

2 radar   

n.雷达，无线电探测器

参考例句：

• They are following the flight of an aircraft by radar.他们正在用雷达追踪一架飞机的飞行。
• Enemy ships were detected on the radar.敌舰的影像已显现在雷达上。

3 detailed   

adj.详细的，详尽的，极注意细节的，完全的

参考例句：

• He had made a detailed study of the terrain.他对地形作了缜密的研究。
• A detailed list of our publications is available on request.我们的出版物有一份详细的目录备索。

4 dunes   

沙丘( dune的名词复数 )

参考例句：

• The boy galloped over the dunes barefoot. 那男孩光着脚在沙丘间飞跑。
• Dragging the fully laden boat across the sand dunes was no mean feat. 将满载货物的船拖过沙丘是一件了不起的事。

5 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。