a Location of the Glatt valley in the northern Swiss Plateau; the arrows mark the dominant ice flow directions for the Glatt valley glacier originating in the Glarus and Graubünden Alps. b Location of the main drill sites (and other sites referred to in the text, elevation data: DHM25 © Swisstopo). c Map of the same extent as (b) reveals thick Quaternary sediment accumulation in buried glacially overdeepened basins (bedrock surface model compiled by Pietsch and Jordan 2014; modern lakes are filled). The thickest sediments occur within the extent of the major glacial basins (modified after Graf 2009). The maximum extent of the Möhlin, Beringen, and Birrfeld Glaciations are shown.