Geologists from Caltech and civil engineers from the China Earthquake Administration have combined forces and discovered an ancient canyon buried in South Tibet.
The canyon is buried along the Yarlung Tsangpo River, north of the Himalayas. Engineers from the China Earthquake Administration collected cores in five locations along the valley floor last year. Jing Liu-Zeng, a graduate student from Caltech, works for the administration, and he brought the data from the cores back to the university.
There researchers analyzed the data and found the canyon was once thousands of feet deep and is three million to seven million years old. They found the canyon was dammed by shifting tectonic plates 2.5 million years ago, which explains why they found large amounts of sediment collected in certain areas.
The new evidence eliminates the theory that the uplift of the Himalayas prevented the rivers from carving deeply into the plateau.
"In tectonics, we are always trying to use rivers to say something about uplift," Jean-Philippe Avouac, the Earle C. Anthony Professor of Geology at Caltech, said. "In this case, we used a paleocanyon that was carved by a river. It's a nice example where by recovering the geometry of the bottom of the canyon, we were able to say how much the range has moved up and when it started moving."
The findings are published in the journal Science.