Quaternary geology

The Quaternary is the most recent period in the Earth’s history: the last 2.6 million years. It is marked by the appearance of man as well as repeated glacial/interglacial cycles, which strongly influenced the mountains and their environment.

3D cross-section of the Birrfeld region
3D cross-section of the Birrfeld region (canton of Aargau): in addition to the undulating ground and bedrock surfaces, the existing boreholes in unconsolidated deposits are also visible (© swisstopo).

Summary

Switzerland‘s present relief forms can to a large extent be traced back to the action of glaciers, rivers and frost of the quaternary ice age, in fact mainly back to the glaciations in the course of the last one million years. The former ice extent can be reconstructed by means of unconsolidated rocks such as moraines, terraces at the edge of the ice and gravel bodies. The layers are thickest in the valleys: up to several hundred meters. Many of these types of deposits contain the most important utilized groundwater resources of Switzerland. They represent natural resources – gravel is an example – or are suitable as land for agriculture.

Who is who

Quaternary geology: Who is who

The Quaternary Geology and Paleoclimatology group at the University of Bern researches in the field of reconstruction of numerous environmental and climate changes of the past, particularly during the Quaternary epochs.


The Swiss Quaternary Society (CH-QUAT) sees itself as an interface for scientists from various fields of research and practice that deal with ice ages (Quaternary) and in particular the aspects Mankind – Environment - Climate.

 

Federal Office of Topography swisstopo, Swiss Geological Survey

 

International Union for Quaternary Research (INQUA)

Data

What did Switzerland look like during the last glacial maximum? Which regions were covered in ice? A paleogeographic map reconstructs the situation using results from the research.
Geological maps and models on the thickness of unconsolidated rocks (mostly Quaternary) form an important foundation for science and practice.
 

Switzerland during the Last Glacial Maximum LGM

The last ice age glaciers reached their maximum extent about 24,000 years ago. The majority of Switzerland lay beneath an up to several hundred meters thick shell of glacial ice. This situation is represented in the paleogeographic map “Switzerland during the Last Glacial Maximum“, informally usually informally called the LGM-Map. It illustrates the latest results of the ice age research, for which many years of field work were required: For example, it was necessary to map glacial deposits such as erratics, or glacial land forms such as moraines and date them using the latest methods. The map includes important updates such as the determination of the central Alpine ice elevations with large ice domes whose surface lay at 2,900 to 3,100 meters AMSL; in addition there is an ice plateau, at a similar elevation, in the southern part of the Matter Valley.

The LGM-Map represents a geological event which significantly shaped Switzerland’s current surface form and which is also significant for example for the formation and distribution of the economically important gravel deposits (as raw material and aquifer). Furthermore, the extent of the glaciers allows the mean annual temperature during the peak of the last ice age to be determined, which lay about 12°C below the present-day value.
 

Bedrock elevation and thickness of the unconsolidated rocks

Since the 1980s, data have been collected by geological, seismic and gravimetric measurements and boreholes, in order to create regional models of the bedrock elevations of Switzerland. The density contrast between unconsolidated sediments and the older, deeper solid rock makes it possible to calculate the thickness of the unconsolidated sediments with gravimetric methods and to place them on maps.

Switzerland’s bedrock elevations have been successively modeled with a high resolution in recent years, based on geological maps, relevant publications and several thousand drill data. The existing composite model is compatible with swisstopo’s DHM25 digital elevation model. The isopach (thickness) map is a synthesis of already published documents, the values obtained by inversion of the Bouguer anomalies and the data supplied by Nagra.


Fundamentals of Geology

Switzerland During the Last Glacial Maximum

Switzerland During the Last Glacial Maximum (vector map)