The ability of climate to influence tectonics has been a field of growing interest for more than a century . Furthermore, the dramatic effect of rainfall on the evolution of mountain landscapes has always been the subject of wide debate among geologists.
Now, a new study carried out by scientists at the University of Bristol (England) has shed light on this ancient enigma. The researchers calculated the impact of the rain, looking at how the peaks and valleys have developed over millions of years, focusing on the most impressive mountain ranges on our planet , such as the Himalayas, the highest mountain range on Earth, and the one that contains to the highest peaks in the world (like Everest).
The study has shown that rain can actually move mountains.
“It may seem intuitive that more rain can shape mountains by turning rivers into rocks faster. But scientists have also believed that rain can erode a landscape fast enough to “suck” rocks out of the Earth, effectively lifting mountains very quickly. Both theories have been debated for decades because the steps required to test them are painstakingly complicated. That is what makes this discovery such an exciting breakthrough, as it strongly supports the notion that reliable terrestrial and atmospheric processes are intimately connected, “explains Byron Adams, Royal Society Fellow Dorothy Hodgkin Fellow at the Cabot Institute for the Environment of the university and leader of the work that publishes the journal Science Advances.
Cosmic clocks
To make a connection between weather patterns and erosion rates, experts dated and accurately mapped quartz sand grains on the slopes of the central and eastern Himalayas in Bhutan and Nepal using a new dating technique that relied on measurement requires a rare element, beryllium-10, in quartz samples.
“Beryllium-10 is produced within quartz when cosmic radiation, mostly neutrons, from outer space travels through the atmosphere and strikes the nucleus of an oxygen-16 or silicon-28 atom in the mineral,” he clarifies. Adams. “When this interaction occurs, the atom breaks or splinters, and new elements are formed, including beryllium-10.”
Beryllium-10, or Be10, is a very rare form of beryllium and “because we know the flux of cosmic radiation and the rate of production of Be-10 in quartz, we can use this technique to keep track of time.” continues the expert. That is, by counting the atoms of Beryllium-10, scientists can measure how long quartz sands have been exposed to the sky at any given location on mountain slopes and in river valleys and see how fast it has been. eroded landscape.
“Once we have the erosion rates for the entire mountain range, we can compare them to variations in river slope and rainfall. However, such a comparison is hugely problematic because each data point is very difficult to produce and statistical interpretation putting all the data together is complicated, “says Adams.
Finally, a numerical model combined with regression techniques was able to accurately predict erosion rates. The model also allowed them to quantify how rainfall affects erosion rates on rugged terrain.
“Our findings show how critical it is to take rainfall into account when evaluating patterns of tectonic activity using topography, and they also provide an essential step in addressing the rate of slippage where tectonic faults can be controlled by surface erosion driven by the climate ”, explains Kelin Whipple, co-author of the work.
The study findings also have significant implications for land use management, infrastructure maintenance and hazards in the Himalayas, as there is a risk that high rates of erosion could dramatically increase sedimentation behind dams. jeopardizing critical hydroelectric projects.
Referencia: B. A. Adams, K. X. Whipple, A. M. Forte, A. M. Heimsath and K. V. Hodges. Climate controls on erosion in tectonically active landscapes. Science Advances, 2020 DOI: 10.1126/sciadv.aaz3166
