The planet is currently in the Quaternary period, which has been defined by the cyclic fluctuations between glacial and interglacial phases. These distinct phases have each shaped the landscape around us in their own ways. Understanding their respective effects and erosional processes helps benchmark current climate models and is key to accurate prediction of future changes.
ln particular, a lot of research has focused on the Last Glacial Maximum (LGM), which occurred approximately 20 kyr aga and was the last major extreme cold phase on the planet. Unfortunately, limited information is available on its climate and landscape evolution since then. This is mostly due to of a lack of: (1) climate proxy material, and/or (2) available techniques capable of resolving this information on the timescale required (101-104 yr). However, in the last five years, two methods have emerged that are able to translate optically stimulated luminescence (OSL) and thermoluminescence (TL) signais in bedrock surfaces into surface erosion rates and paleotemperatures, respectively.
ln this thesis, 1 begin by developing an optimum measurement protocol to reduce scatter in OSL results. 1 then combine three OSL signais with in-situ 10Be measurements to constrain the post-glacier erosion rates of six bedrock samples next to the Gomer glacier, Switzerland. My results reveal bedrock surface erosion rates that vary from 9.72 x 10-2 to 1.51 x 10-1 mm a-1 over a ~ 650 m elevation gradient, and an anti-correlation between erosion rate and altitude. These observations are surprising but in agreement with results from another study nearby at the Mer de Glace, France. ln addition, through a global compilation, 1 show that periglacial erosion rates in mountain environments are higher than previously anticipated, but that glacial erosion rates remain larger. These two observations could have important implications for landscape evolution models as they shed insight into the dominant contrais on the erosional processes that shape mountain environments.
As for LGM climate, using feldspar TL and an ice extent inversion model, 1 find that temperatures in the Western European Alps at the end of the LGM were ~9 °C colder than today and up to 85% drier. This emphasizes the presence of continental variability in LGM climate and the need for further investigations in the matter to improve climate models. Furthermore, our results suggest that the presence of a large ice cap over Europe during the LGM is unlikely due to large changes in atmospheric circulation patters, leading to increased precipitation, but rather through the presence of colder and drier conditions.