China's eighth largest desert, the Kumtag, has been measured to cover 22,917.2 square kilometers, according to scientists who have just returned from a month-long expedition there, Xinhua News Agency reported on Sunday.

A team of 15 participated in the first full-scale scientific expedition across the desert, said Wang Jihe, the researcher from Gansu Provincial Sand Control Institute who headed it.

This is the first time Chinese scientists have measured the precise size of the desert, between Lop Nur in Xinjiang Uygur Autonomous Region and Dunhuang, Gansu Province and with the Tianshan Mountains to the north and Altun Mountains to the south.

Wang said scientists from his institute, the Chinese Academy of Forestry Science and Lanzhou University, walked more than 5,000 kilometers across the desert and used remote sensing satellite images, coupled with results of field surveys, to work out its precise area.

They also collected more than 500 animal and vegetation specimens and at least 1,000 geological readings, discovered two stratum sections that have since proven valuable, and provided evidence to support further study on the desert's geological conditions, soil, vegetation, climate changes and changing river and lake systems.

Beneath the Kumtag's sand and rock, scientists found clear signs of a vast dried-up lake. Wang said the team collected more than 100 stratum samples and hoped further analysis may tell how the rise of the Qinghai-Tibet Plateau induced climate changes in the arid northwest, how the Kumtag came into being and how Lop Nur, once a vast lake, kept shrinking and dried up entirely in 1972.

The team also spotted 25 wild two-humped Bactrian camels, a critically-endangered species, in the central part of the desert. According to Ma Muli, a forestry official in Jiuquan city of Gansu, the Kumtag is home to about 260 of the camels. "Most of them moved here after Lop Nur dried up," said Ma, who was also a guide for the expedition team.

Very little is known about the Kumtag, whose name means "sand hill" in the Uygur language, which has the toughest natural conditions in northwest China's arid region.

(Xinhua News Agency October 25, 2005)