Research

The Glacial Geology Research Group specializes in examining the interactions between the geosphere, climate, and human societies throughout the Quaternary period—the last 2.6 million years of Earth's history. Our primary focus is on the geological archives that shed light on these interactions. By reconstructing the chronology of these sedimentary archives, we gain insights into the dynamics of these interactions in the past and their potential future implications. Our analysis, set within a detailed chronological framework, aims to elucidate the causes, rates, and patterns of landscape evolution, including its timing, magnitude, and frequency. We primarily investigate terrestrial sedimentary archives, which are characterized by their vertical and lateral discontinuities and frequent hiata, making them challenging to correlate stratigraphically due to their complex and often counterintuitive topographic relationships. Our approach encompasses more than the traditional geologist’s toolkit of morphological and lithological analysis. Given the complexities of the terrestrial archives, establishing absolute time control is crucial. We strive to unravel these challenges through quantitative data collection, involving detailed fieldwork, laboratory methods, precise time calibration, and modeling.

Cosmogenic nuclide analysis

The Surface Exposure Dating Laboratory was established at the Institute of Geological Sciences in 2002, within the scientific collaboration on cosmogenic nuclide methodology applications between the Institute of Geological Sciences at the University of Bern, the Laboratory for Ion Beam Physics and the Department of Earth Sciences at ETH Zurich that started in the early 1990s. Initially focusing on the use of cosmogenic ¹⁰Be to address challenges in Earth Science, the laboratory has since expanded its toolkit to include fault-scarp, depth-profile, and isochron-burial dating techniques. This expansion has fostered a rich tradition and extensive experience in using cosmogenic nuclides (including ¹⁰Be, in-situ ¹⁴C, ²⁶Al, and ³⁶Cl) for determining the timing of events and rates of landscape change. Our research integrates field data with diverse dating methodologies to investigate various geological processes:  (1) reconstructions of the glacial dynamics in Turkey, the Alps, Scandinavia, Africa and in Antarctica; (2) the quantification of uplift rates of an entire continent in response to glacial unloading; (3) the quantification of landscape changes through dating and mapping of fluvial terraces; and (4) the quantification of rupture rates of the normal faults. The laboratory has played a pivotal role in leading and participating in cutting-edge national and international research projects, securing external funding, and fostering scientific collaborations across four national and over twenty international institutions. This engagement resulted in the successful AMS analyses of >2000 ¹⁰Be, >1000 ³⁶Cl and >500 ²⁶Al samples from rock surfaces and sediments. These efforts have contributed to over 100 scientific publications in the fields of Quaternary Geology, Earth Surface Dynamics, and Tectonics. Today, the Surface Exposure Dating Laboratory in Bern is recognized as a dynamic hub, offering vital infrastructure and support to over 10 research groups from various countries.

Quaternary Glaciations

We have been studying Quaternary glaciations across various regions including Turkey, Ethiopia, Scandinavia, and the Alps for many years. In 2017, we embarked on a research initiative to examine the evolution of the Eastern Antarctic Ice Sheet in Queen Maud Land, Antarctica. This project saw us partnering with the International Polar Foundation (Belgium), Turkish Polar Research Institute, and Swiss Polar Institute, participating in the BELARE 2017-18 and 2018-19 Antarctic expeditions during the austral summers of those years. Our findings from these expeditions indicate that the Eastern Antarctic Ice Sheet maintained stability from the late Miocene through to the Pliocene, after which it experienced surface fluctuations. Notably, we showed that the ice sheet's drainage system underwent reorganization before 1 Ma and has since shown a dramatic response to global climate changes since the Lateglacial period, more significantly than previously understood. To delineate the timing of these changes, we employed a novel approach using in-situ cosmogenic ¹⁴C analysis, complemented by traditional paired analyses of ¹⁰Be, ²¹Ne, ²⁶Al, and ³⁶Cl isotopes. This multiple nuclide analysis led us to conclude that in regions with prolonged low erosion rates, like Antarctica, the landscape's inheritance can obscure true exposure histories, sometimes by less than a few tens of thousands of years.

Glaciostatic Uplift

Since 2012, our collaboration with the Norwegian Geological Survey and the Norwegian University of Science and Technology in Trondheim has focused on studying the fluctuations of the Scandinavian ice sheet during the Lateglacial period (18-12 ka) across southwest, central, and northern Norway. In 2017, we expanded our research to include the isostatic rebound of the lithosphere resulting from the deglaciation of Scandinavia. Our work involves quantifying and integrating the history of regional differences in unloading (chronology of the driver through surface exposure dating of the glacial extents) and the regional pattern of shorelines rising (chronology of the response through surface exposure and depth-profile dating of raised shorelines). This combined approach helps us understand the temporal variation in isostatic response, which is vital for grasping the post-glacial landscape evolution at a regional level. Accurately measuring isostatic uplift rates is essential for reconstructing the changes in the paleo-ice surface of the Scandinavian Ice Sheet. Our findings indicate that the glaciostatic rebound of the Scandinavian shield began before approximately 1 3ka ago, following the deglaciation of northern Norway's outer coasts around 14 ka ago during the Lateglacial period.

Landscape Evolution

For over a decade, our research has focused on the Swiss Deckenschotter, composed of glacial and outwash sediments from the Early and Middle Pleistocene glaciers on the Northern Swiss Alpine Foreland. The morphostratigraphy of these deposits is well established, whereby topographically higher deposits are considered to be relatively older than topographically lower deposits. Despite this, the precise chronology of the Deckenschotter has remained elusive due to the lack of suitable dating techniques, a significant gap given the relevance of these deposits for selecting nuclear waste disposal sites in Switzerland. In collaboration with the Swiss Federal Nuclear Safety Inspectorate and ETH Zurich since 2011, our research aims to pinpoint the deposition timing of the Swiss Deckenschotter, both before and after the Mid-Pleistocene Revolution. We seek to understand how erosional processes and rates evolved during this climatic shift and to provide quantitative data for sediment budget assessments over this period. Our work using depth-profile and isochron-burial dating techniques has led to the first quantitative chronostratigraphy of these formations. Our findings indicate that the Swiss Deckenschotter consists of cut-and-fill sequences laid down from the start of the Quaternary up to the Mid-Pleistocene Revolution around 1 million years ago.

Rupture rates of the normal faults

Since 2007, our team has been investigating the seismic history and slip rate of bedrock normal fault planes. This research is critical because models that predict long-term earthquake frequency and magnitude, extending beyond the historical records, are essential for assessing seismic vulnerability and mitigating natural hazards. These models need to integrate field observations with records of multiple, well-dated earthquakes. However, paleoseismic records are scarce due to the challenges in identifying landforms and sediments that capture fault activity, which are often obscured by erosion, burial, or subsequent seismic events. A key indicator of past seismic activity is a bedrock scarp, which not only provides clear evidence of seismic movements but also indicates the ongoing tectonic forces shaping the landscape. Cosmogenic nuclide dating, particularly with in situ produced cosmogenic ³⁶Cl, is a unique method that can directly date these bedrock scarps, offering insights into the seismic history and slip rates of fault planes. Our research focused on three major fault systems in western Anatolia, a region known for its high tectonic and seismic activity. We developed a simulator using cosmogenic ³⁶Cl concentrations to model seismic ruptures and active periods along normal fault scarps. After analyzing over 400 samples for ³⁶Cl, we identified evidence of at least 19 seismic events ranging from magnitude 5.5 to 7.5 during the Holocene period, providing a detailed account of the seismic history in western Anatolia.