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Abstract:
The Earth’s surface is constantly changing. Sometimes these changes are very fast. When glaciers shrink or when natural disasters
such as landslides or volcanic eruptions occur, their impact on landscapes can directly be observed. Other changes are too
slow to be observed by the human eye. Such slow changes still form lofty mountain ranges like the Himalaya, because tectonic
forcing has uplifted them persistently by a few millimeters each year over many millions of years. Such mountain ranges affect
wind and rain patterns and thus the water cycle, and, by the process of erosion, they deliver sediment to valleys and floodplains
where fertile soils form. Rare radioactive or stable cosmogenic nuclides have become the state-of-the-art clocks to time these
rates of change in all kinds of landscapes. Produced by cosmic ray bombardment in the atmosphere or in minerals at the Earth’s
surface, they are used to date landforms and to measure the erosion rate of landscapes. For example, we apply them to constrain
the ages of glacial surfaces over hundreds to thousands of years. In river sediments they tell us how fast a mountain range is
eroding and how much sediment is exported from a catchment. When buried in the sedimentary record, they inform us on erosion
rates in the geologic past. Because of their power to infer landscape-forming forces, cosmogenic nuclides allow to predict the impact
of changes of the human habitat induced by man.
