(ORDO NEWS) — Comparing the rate of growth and erosion of mountains in different regions of the Alps, geologists have found that in the central part of this ridge, mountains continue to grow rapidly. Over a thousand years, they become about 40 cm taller. An article describing the study was published by the scientific journal Earth-Science Reviews.
On Earth, mountains are formed at the junction of lithospheric plates – huge areas of the earth’s crust. These plates are constantly moving, but at a very small distance – a few millimeters in thousands of years. For example, about 150 million years ago, the Adriatic plate began to move towards the Eurasian plate, as a result of which the Alps began to form. This movement continues today, thanks to which the Alps are still growing.
Previously, it was believed that the growth of mountains is balanced by erosion – the destruction of rocks under the influence of wind, water, sunlight and other reasons. Geologists led by Romain Delunel from the University of Bern (Switzerland) decided to find out how fast the Alps are growing and whether erosion really keeps up with this process.
To find out, the scientists analyzed samples of quartz sand from the bottom of more than 350 rivers flowing in the alpine region. This sand is formed as a result of erosion, rains wash it out of the rocks and eventually it ends up in local water courses.
Scientists calculated how much beryllium-10 was in the quartz particles, an isotope that is formed as a result of a nuclear reaction caused by cosmic particles. The longer quartz is on the planet’s surface, the longer it is exposed to cosmic radiation and the more beryllium-10 it contains. Thus, calculating the concentration of this isotope helps to calculate the age of a particular surface.
It turned out that the Alps are growing much faster than they are destroyed. The rate of erosion in different regions was different: the fastest of all the mountains were destroyed in the south-west of Switzerland, in the canton of Valais: there, over a thousand years, the ridge lost about 75 cm.Erosion is slowest in the east of Switzerland – about 14 cm over the same period. On average, the erosion rate fluctuates around an indicator of 40 cm per millennium.
“This was a big surprise because we used to think that Alpine growth and erosion were in balance,” said one of the authors of the work, Fritz Schluenegger of the University of Bern. The fact is that over a thousand years the central Alps become about 80 cm taller. That is, the difference between growth and destruction in the center of the Alps is about 40 cm. “This means that the central Alps are still growing, and growing rapidly.”
At the same time, in the eastern Alps, erosion balances growth, and in the western Alps it occurs even faster.
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