Quaternary boreholes – learning from the past to prepare for the future
Deposits from the Quaternary – the most recent geological era from around 2.5 million years ago to the present – provide information on past erosion processes and tectonic activity. For this reason, Nagra has investigated these unconsolidated rocks by drilling boreholes.
The data from the Quaternary boreholes can be used to reconstruct and better understand past erosion processes and tectonic activities, allowing for more reliable predictions on the future evolution of the landscape.
Such predictions are important with regard to the post-closure safety of a deep geological repository and its protection against the removal of rock layers (erosion).
In contrast to the Quaternary boreholes, the primary purpose of Nagra’s deep borehole campaign was to investigate deeper layers of rock.
Learn more about the deep borehole campaign
Where were boreholes drilled?
The Quaternary boreholes were used for the geological investigation of selected areas of Northern Switzerland. The exact locations of the boreholes depended on where the Quaternary deposits of unconsolidated rocks occur and on information from previously conducted seismic measurements.
Unconsolidated rocks are mainly found near present-day river courses that often follow troughs once formed by glaciers and later refilled. Nagra investigated troughs such as these in the lower Aare Valley, the “Riniker” Feld and the Thur Valley from 2018 to 2020. A total of eleven Quaternary boreholes were drilled.
In-depth analyses of rock samples
Nagra and its partners continued to analyse the drill cores long after the boreholes had been drilled to investigate the Quaternary geology. The Institute of Geological Sciences of the University of Bern conducted chemical and geotechnical analyses. These provide information on what type of unconsolidated rock fills the troughs and what properties the rocks have. The age of the drill cores was also determined, involving a very complex process.
For every Quaternary borehole, Nagra published a report summarising all measurement data.
To the reports
