High topography may have existed at the eastern margin of the Tibetan Plateau during the early stages of collision between the Indian and Asian continents about 30 million years ago, suggests a study published online this week in Nature Geoscience. Previously, the high elevations across much of eastern Tibet were thought to have developed just 10 to 15 million years ago.

Erchie Wang, Eric Kirby and colleagues dated episodes of topographic growth in eastern Tibet by analysing the timing of rock cooling caused as erosion in the mountains exhumed rocks toward the cool Earth surface. After an initial, early period of steady topographic growth, the plateau’s margin later grew during two rapid pulses of mountain building. The authors suggest that this prolonged and episodic nature of the mountain growth may indicate that two different physical mechanisms helped to build the high topography in eastern Tibet.