Valentin Gasser / Departement of Earthsciences / ETH Zürich, Switzerland
Mapping and dating of geomorphological features in the forefield of the Silvretta glacier
The Silvretta glacier is located east of Klosters in the uppermost Prättigau, canton of Grisons, close to the Austrian border. To the west of the 2.8 km long glacier there are several distinct moraine ridges from which some are thought to be older than Little Ice Age (LIA).
In my master’s thesis the forefield of the Silvretta glacier was mapped in August 2021. The field maps are merged into a geomorphological map using ArcGIS Pro. For this, also aerial photos from different times and digital elevation models based on LiDAR data are taken into account.
For the age determination of the geomorphological features (especially the moraine ridges) different approaches were chosen:
The young moraines inside the LIA extent of the glacier can be dated with the help of historical photos, maps and human marks showing the glacial extent at a certain time.
As there are no good maps older than 1853 the ages of the moraines outside the LIA extent are very unclear. Therefore, cosmogenic nuclide dating has to be applied. 12 samples from big boulders on the moraines I am interested in were taken at the beginning of September 2021. Through the exposure dating (10Be in quartz) the age of the moraines outside shall be determined.
As the Silvretta glacier is one of the most monitored glaciers of the Swiss alps since more than 60 years it would be interesting to obtain information about its older history.
The fieldwork during August and the beginning of September was only possible with overnight stays in the Silvretta hut SAC which were generously payed by CH-QUAT. I am very thankful for this support.
Mattia Binaghi/ Institute of Geological Sciences/ University of Bern, Switzerland
Post-LGM Glacier Fluctuations in the northern Valaisian Alps
In my MSc. Thesis study, I focus on the reconstruction of the post-LGM glacier evolution in the Valaisian Alps after the Last Glacial Maximum (LGM) in the Canton of Valais, Switzerland. I want to find out when and how large the Valasian glaciers were in addition to the climatic conditions which caused the fluctuations of these glaciers. For this, I explore the glacial landforms in the three of the northern tributary valleys (Belalp, Lüsgenalp, and Oberaletschgletscher) of the Great Aletsch glacier, the longest glacier of the Swiss Alps. The study area is situated at an altitude between 1800 and 2700 m a.s.l, and covers a total area of about 13.2 km2. The landscape here is glacially overprinted and contains well-preserved moraines.
I would like to express my sincere gratitude to CH-QUAT for financially supporting my fieldwork. This support enabled me to go to the field several times between August and September 2021. During this time, high-resolution aerial photographs were taken with an unmade air vehicle. These photographs were subsequently processed using photogrammetry program to generate orthophotographs and digital elevation models (DEMs) for the detailed field mapping of the study area. To reconstruct the chronology of the glacier fluctuations, I collected 14 samples in Lüsgenalp for surface exposure dating. They are from top surfaces of the erratic boulders located on crestlines of the moraines. The samples will then be dated in Fall 2021 using the cosmogenic nuclide 10Be. Later, the paleoglaciers of Belalp and Lüsgenalp will be modeled using GlaRe® and ELA® (toolboxes of ArcGIS®) to determine the equilibrium line altitudes and thus to calculate the paleotemperatures. At the end, the regional paleoclimatic conditions of the northern Valaisian Alps will be reconstructed by comparing our results with other glaciers of the region.
Zitong Lou/Summer research at the Department of Earth Science / ETH Zurich, Switzerland
Investigating the distribution of bacterial tetraether membrane lipids and the stability of soil organic matter in a Swiss peatland.
Etang de la Gruère is an ombrotrophic bog in the Franches Montagnes region of the Swiss Jura mountains. As an ombrotrophic peatland which is elevated above drainage level, precipitation is the main source of water and nutrient. Its continuous build-up since 12ka and sensitivity to climate change (precipitation and temperature) make it a suitable site for paleoclimate reconstruction (e.g. Roos-Barraclough et al. (2004), Weijers et al. (2011)). In this project, to investigate the impact of climate change in the peatland, we used techniques from three different disciplines (sedimentology, biogeochemistry, and geochemistry); Rock-Eval analysis, biomarker analysis and XRF elementary analysis. The biomarker lipid targeted in this study are branched glycerol dialkyl glycerol tetraethers (brGDGTs).
Thanks to the financial support from CH-QUAT, I visited Etang de la Gruère (Canton of Jura) and was able to visit the Institute of Earth Sciences at the University of Lausanne (Canton of Vaud). During the field trip, I collected more vegetation samples and a surface soil. Both new and previously collected peat samples (PI: Dr. Cindy De Jonge) were prepared for and subjected to a Rock-Eval analysis at the University of Lausanne.
Vicente Melo Velasco / Departement of Earthsciences / ETH Zürich, Switzerland
Reconstructing Holocene glacial history at Leg Grevasalvas catchment (Graubünden, Switzerland)
Thanks to the support of the CH-QUAT association, I was able to carry out a total of 9 days of fieldwork during the summer of 2021, covering the costs of accommodation and travel. During those days I worked on a geomorphological map (mainly gathering information and making observations about glacial landforms and erosion features) and collected samples to perform dating using cosmogenic nuclides in the laboratory of Ion Bean Physics at ETH Zürich.
The data and samples collected during the fieldwork will allow me to work on my thesis, which has as an aim to study the Holocene glacial history at Leg Grevasalvas catchment (Graubünden, Switzerland), for then to be compared with other sites for Alpine-wide paleoclimate analysis. Understanding these landforms, how and when they developed is of great interest since the are no previous studies in this area that address these issues in such a local scale as the one proposed in this research.
Vicente Melo Velasco
Isabel Schumacher / Departement of Earthsciences / ETH Zürich, Switzerland
Reconstruction of the timing and runout of the Voralpsee landslide, Kanton St. Gallen
The Voralpsee landslide is situated in the Voralpsee valley just between the Churfirsten mountain chain and the Alvier mountains in eastern Switzerland (2'747'476/1'225'159). The landslide created a 30 million m3 deposit that covered the Voralpsee valley over a distance of 3 km. Based on field relations earlier investigators placed the event in the late Pleistocene and assumed a two stage emplacement of the deposit (Keller 19881). The release area is situated at a height of 2042 m a. s. l. at the Chapf peak and is comprised of a 300 m high wall composed of the Tierwis, Schrattenkalk and Garschella Formation. It is thought that the landslide damned the headwaters from the Voralpsee valley and created the Voralpsee lake (1124 m a.s.l.) (Heim 19322, Keller 19881).
The Voralpsee landslide is widely known in the scientific world for its outstanding long runout distance (2 km). However, little work has been done to investigate the time of the event as well as to reconstruct the runout pattern of the landslide. The objective of the master thesis is on one hand to obtain the age of the Voralpsee landslide deposit by surface dating and find out if the deposit was created in one event or several events. And on the other hand, to model the failure and the emplacement of the deposit to find out more about the mechanisms and significant parameters involved in such large rock avalanche. The behavior of rock avalanches is still subject of actual investigation and a lot of open questions remain. The comprehension of the behavior of large rock avalanches is very important as a greater understanding of the mechanisms that lead to such large deposits can contribute to the prevention of the catastrophic effects of future events.
Thanks to the support of CH-Quat I was able to stay 5 days in the Voralpsee valley in July 2020 to map the extent of the landslide deposit and to sample different boulders for surface dating. Thanks so much for the financial support, CH-Quat!
1Keller, O. (1988). Ältere spätwürmzeitliche Gletschervorstösse und Zerfall des Eisstromnetzes in den nördlichen Rhein-Alpen: Weissbad-Stadium/Bühl-Stadium. Geographisches Institut der Universität.
2Heim, A. (1932). Bergsturz und Menschenleben (No. 20). Fretz & Wasmuth.