Caves and their dripstones tell us about the uplift of mountains

In one of his songs Bob Dylan asks "How many years can a mountain exist before it is washed to the sea?", and thus poses an intriguing geological question for which an accurate answer is not easily provided. Mountain ranges are in a constant interplay between climatically controlled weathering processes on the one hand and the tectonic forces that cause folding and thrusting and thus thickening of the Earth's crust on the other hand. While erosion eventually erases any geological obstacles, tectonic forces are responsible for pilingand lifting-up rocks and thus for forming spectacular mountain landscapes such as the European Alps. In reality, climate, weathering and mountain uplift interact in a complex manner and quantifying rates for erosion and uplift, especially for the last couple of millions of years, remains a challenging task. In a recent Geology paper Michael Meyer, University of Innsbruck, et al. report on ancient cave systems discovered near the summits of the Allgäu Mountains (Austria) that preserved the oldest radiometrically dated dripstones currently known from the European Alps. "These cave deposits formed ca. 2 million years ago and their geochemical signature and biological inclusions are vastly different from other cave calcites in the Alps" says Meyer, who works at the Institute of Geology and Paleontology at the University of Innsbruck, Austria.