Manfred Strecker, Heike Kampe, Sabine Sütterlin, Antje Horn-Conrad, Matthias Zimmermann, Barbara Eckardt, Petra Görlich

• The latest edition of our Potsdam Research Magazine “Portal Wissen” addresses the topic “Layers” in many different ways. Geoscientists often deal with layers: layers of soil, sediment, or rock are the evidence of repeated and long-lasting processes of erosion and sedimentation that took place in the early history of the earth. For instance, mountains are eroded by water, ice and wind. The sand that results from that erosion might eventually form a new layer on the ocean floor known as a sediment horizon. After tens of millions of years, tectonic plate movements can deform the ocean floor, pushing it upwards as mountains are created, bringing the layers of sand from former mountain chains together with fossilized sea dwellers into the realm of climbers and mountaineers – a fundamental cycle within the Earth system that was succinctly described by Ibn Sina nearly 1000 years ago, and later by Charles Darwin when he was crossing the Andes. The landscape around us overlays the products of recent processes with those from the past. SlowThe latest edition of our Potsdam Research Magazine “Portal Wissen” addresses the topic “Layers” in many different ways. Geoscientists often deal with layers: layers of soil, sediment, or rock are the evidence of repeated and long-lasting processes of erosion and sedimentation that took place in the early history of the earth. For instance, mountains are eroded by water, ice and wind. The sand that results from that erosion might eventually form a new layer on the ocean floor known as a sediment horizon. After tens of millions of years, tectonic plate movements can deform the ocean floor, pushing it upwards as mountains are created, bringing the layers of sand from former mountain chains together with fossilized sea dwellers into the realm of climbers and mountaineers – a fundamental cycle within the Earth system that was succinctly described by Ibn Sina nearly 1000 years ago, and later by Charles Darwin when he was crossing the Andes. The landscape around us overlays the products of recent processes with those from the past. Slow processes or extreme events that happen very rarely – like floods, earthquakes or rockslides – wipe out certain characteristics, while others remain on the surface. In this sense, the landscape is like a palimpsest – a piece of parchment that monks in the Middle Ages scraped clean again and again to write something new. Analysing rock layers and soil is similar to the work of a detective. Geophysical deep sounding with sound and radar waves, precise measurements of motions related to earthquakes, and deep boreholes each provide a glimpse of the characteristics of what lies beneath us, giving us a better understanding of spatial distribution of the various layers. Fossils can tell us the age of a layer of sediment, while radiometric isotopes in minerals reveal how quickly a rock moved from deep within the Earth up to the surface, perhaps during the process of mountain building. Thin layers of ash tell us when there was a devastating volcanic eruption that influenced environmental conditions. The shape, gradation, and surface conditions of sand grains reflect whether wind or water was responsible for their transport. We know, for instance, that northern Germany was a desert landscape more than 260 million years ago. At that time, the wind made huge dunes migrate across the region. Over time, climate and vegetation slowly alter the physical and chemical characteristics of sand and rock at the surface, turning them into soil, the epidermis of our planet. Mineralogical analyses of layers of the soil layer tell us whether the climate was dry or wet. These kinds of observations allow us to reconstruct links between our climate system and processes that have taken place on the Earth’s surface, as well as those processes that originate at much deeper levels. The clues we use might be hidden under the surface of the earth or clearly visible on the surface, like in the mountains, or even in freshly cut rock alongside roads. On the following pages, we invite you to accompany scientists from Potsdam into their world of research. They track hidden traces of longgone earthquakes in the Tien Shan Mountains; they discover ancient forms of life in deep-sea sediments. They even examine layers in outer space that can tell us something about the formation of planets. “Portal Wissen” not only presents scientists of the University of Potsdam who deal with the sequence of layers formed by solid rock, but also those scientists who deal with levels of education or social strata. Research scientists explain how to implement the social mission of inclusion in teaching, and how pupils from the Berlin district Kreuzberg examine language in urban neighbourhoods together with students from the University of Potsdam. Although these types of “layers” are very different, they all have something in common. Their structure and profile are evidence of continuously changing conditions. The present will leave traces and layers that future geoscientists will measure and examine. We already speak of the Anthropocene, a geological era dominated by humans, which is characterized by far-reaching changes in erosion and sedimentation rates, and the displacement of natural habitats. I hope that you will discover exciting and inspiring stories in this edition. And remember – it is always worth having a look beneath the surface. Prof. Manfred Strecker, PHD Professor of Geology…