Scientists from the California Institute of Technology and the China Earthquake Administration say they have discovered a deep, ancient canyon buried under the Yarlung River in the south of China's Tibetan Autonomous Region.
The study found that about 2.5 million years ago, the Yarlung River had created a deep canyon at least 500 meters (more than 1,640 feet) below its current riverbed.
“The data tells us that the river had [cut] deeply into the margin of the Tibetan Plateau, and then at a later stage the tectonic uplift created the gorge and made this river so steep,” said Dirk Scherler, a geologist and one of two lead authors of the study.
The study, published by the American Association for the Advancement of Science, shows that as the collision of the Indian Plate and the Eurasian Plate lifted the Tibetan Plateau, sediment from the tectonic activities filled the ancient canyon. Through drilling, the scientists determined that the ancient canyon was, in some areas, up to 1,000 meters deep.
“I was extremely surprised when my colleagues, Jing Liu-Zeng and Dirk Scherler, showed me the evidence,” said Jean-Philippe Avouac, the Earle C. Anthony Professor of Geology at Caltech. “That was a big discovery, in my opinion.”
According to Scherler, who now works at GFZ German Research Center for Geosciences, the buried canyon extends for about 300 kilometers (186 miles) upstream from the Yarlung Tsangpo Grand Canyon, a well-known gorge that is about as deep as the U.S. Grand Canyon.
This report was produced in collaboration with the VOA Tibetan service.