When drilling more than 160 meters deep into the earth, scientists from the Lop Nor Environmental Science Drilling Project found special deposits that, on analysis, show Lop Nor used to be a very deep freshwater lake 1.8 - 2.5 million years ago.
The deposits found were 60-meter-long indigo silts. It is known that indigo silt only occurs when a lake is very deep and the waters at the bottom suffer from oxygen deficiency. The silt produced by the No. 1 Drilling Station recently was yellow and rich in gypsum, and the result of freshwater deposits.
Fang Xiaomin, a researcher from the Institute of Earth Environment of the Chinese Academy of Sciences in charge of the project, said that compared with the samples found earlier, the latest findings indicated the area used to have ample rainfall and the lake was a very deep one that extended over vast distances, even into the Taklamakan Desert. "The period was estimated 1.8 - 2.5 million years ago," he added.
Scientists also found some shells offering further proof that Lop Nor used to be a freshwater lake. After careful study, they concluded that Lop Nor suffered a strong drying incident 800,000 years ago, but it didn't dry up completely. However, the drying resumed and continued over a prolonged period of time so that Lop Nor completely dried up and became a desert in 1972.
According to these studies and the stratigraphic succession distribution or time-layer studies of the lake deposits, scientists have made preliminary analysis that the drying up process has occurred gradually at different periods of time.
(China.org.cn translated by Li Jingrong October 14, 2003)
