Are the Alps growing or shrinking?

Nov 05, 2009

The Alps are growing just as quickly in height, as they are shrinking. This paradoxical result could be proven by a group of German and Swiss geoscientists. Due to glaciers and rivers about exactly the same amount of material is eroded from the Alp slopes as is regenerated from the deep Earth's crust. The climatic cycles of the glacial period in Europe over the past 2.5 million years have accelerated this erosion process. In the latest volume of the science magazine "Tectonophysics" ( No. 474, S.236-249) the scientists prove that today's uplifting of the Alps is driven by these strong climatic variations.

The formation of the through the collision of the two continents Africa and Europe began about approximately 55 million years ago. This led to the upthrusting of the highest European mountains, which probably already achieved its greatest height some millions of years ago. At present, however, the Swiss Alps are no longer growing as a result of this tectonic process.

Swiss geodesists, who have already been measuring the Alps with highest accuracy for decades, have observed, however, that the Alp summits, as compared to low land, rise up to one millimetre per year. Over millions of years a considerable height would have to result. But why then are the Alps not as high as the Himalayas? Researchers from the GFZ German Research Centre for Geosciences were able to calculate that mountains eroded concurrently at almost exactly the same speed.

"This mountain erosion cannot even be determined using the highly precise methods of modern geodesy" explains Professor Friedhelm v. Blanckenburg from the GFZ. "We use the rare isotope Beryllium-10, which develops in the land surface via . The quicker a surface erodes, the fewer of this type are present therein". Therefore, von Blanckenburg, and the GFZ geoscientist, Dr. Hella Wittmann, have analysed this "cosmogenic" isotope in the sand of the Swiss Alps rivers and, thus, in the direct products of erosion.

How does it come about now that the Alps erode at the same speed that they rise? "Here pure upthrusting forces are at work. It is similar to an iceberg in the sea. If the top melts, the iceberg surfaces out of the water by almost the same share" explains von Blanckenburg. Thus this paradoxical situation with the Alps that through wind, water, glaciers and rock fall, they are being constantly finely eroded from the top but on the other hand, regenerated from the Earth's mantle. This phenomenon, even if already postulated theoretically has now been proven for a complete mountain range for the first time.

Thus, the Alps are constantly rising, although they have been deemed "dead" in a tectonic sense. Instead of plate forces it is the strong since the beginning of the so-called quaternary glacial before approximately 2.5 million years, to which mountain slopes in particular have been reacting so sensitively. This holds the Alps in motion.

Source: Helmholtz Association of German Research Centres (news : web)

Explore further: New detector sniffs out origins of methane

add to favorites email to friend print save as pdf

Related Stories

Impact of rainfall reaches to roots of mountains

Apr 20, 2006

The erosion caused by rainfall directly affects the movement of continental plates beneath mountain ranges, says a University of Toronto geophysicist — the first time science has raised the possibility that human-induced ...

Study: Alpine glaciers may nearly vanish

Apr 04, 2006

The World Glacier Monitoring Service is warning Europe's Alps might lose three-quarters of its glaciers to global warming during the coming century.

How deep is Europe?

Apr 30, 2008

The Earth's crust is, on global average around 40 kilometres deep. In relation to the total diameter of the Earth with approx. 12800 kilometres this appears to be rather shallow, but precisely these upper kilometres of the ...

Recommended for you

New detector sniffs out origins of methane

12 hours ago

Methane is a potent greenhouse gas, second only to carbon dioxide in its capacity to trap heat in Earth's atmosphere for a long time. The gas can originate from lakes and swamps, natural-gas pipelines, deep-sea ...

The tides they are a changin'

17 hours ago

Scientists from the University of Southampton have found that ocean tides have changed significantly over the last century at many coastal locations around the world.

Lightning plus volcanic ash make glass

Mar 03, 2015

In their open-access paper for Geology, Kimberly Genareau and colleagues propose, for the first time, a mechanism for the generation of glass spherules in geologic deposits through the occurrence of volcan ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.