A scientific drilling was conducted into a bedrock trough (overdeepening) in Bern-Bümpliz (Switzerland) in an effort to advance the knowledge of the Quaternary prior to 150 000 years ago. We encountered a 208.5 m-thick succession of loose sediments (gravel, sand and mud) in the retrieved core and identified two major sedimentary sequences (A: lower, B: upper). The sedimentary suite records two glacial advances and the subsequent filling of a lake sometime between 300 000 and 200 000 years ago.