Glossar

 

Geology of Switzerland

The underground environment of Switzerland is highly diverse.

In Switzerland, it is possible to find a rich variety of rock types and landscape features over a relatively small area.

During the geological history of the Earth, the area that is now Switzerland was covered several times by an ancient sea. Evidence of this exists in the form of the thick limestone layers in the Jura region and the Helvetic Zone.

During the formation of the Alps, rock material removed by erosion was deposited as molasse in the Swiss Plateau in front of the rising mountain chain.

Switzerland can be divided from north to south into four distinct units.

Folded and Tabular Jura
Molasse – Plateau
Helvetic Zone – Northern Alps
Crystalline – Central and Southern Alps

Folded and Tabular Jura

The Swiss Jura Mountains comprise the Folded Jura and the Tabular Jura that form the western and northern margins of Switzerland. The mountains consist mainly of limestone, marl and clay, as well as anhydrite/gypsum.

Around 15 to 10 million years ago, the pressure from the formation of the Alps affected the area of Northern Switzerland. This pressure folded the rocks in the region, resulting in the Folded Jura.

The Creux du Van (Canton Neuchatel) is an example of thick limestone deposits from the Jurassic period some 160 million years ago. The immense rock arena was formed by folding and erosion and is one of the most impressive places in the Jura. Image: Nagra

 

Molasse – Plateau

The Molasse Basin extends from Lake Constance to Lake Geneva. Over the last 30 million years, Large amounts of eroded material accumulated in the foreland basin to the north of the uplifting Alps. The subsurface consists of sandstone, silt and marl as well as Nagelfluh (conglomerate).

A distinction is made between marine and freshwater molasse, depending on whether the sediments were deposited in the sea or in lakes and river valleys.

These deposits are overlain by unconsolidated rocks from the ice ages that were transported to their location by glaciers.

Landscape in the Zürcher Weinland region looking over the Molasse Basin towards the Alps on the horizon. Image: Nagra

Helvetic Zone – Northern Alps

The Helvetic Zone forms the northern margin of the Alps from Lake Thun to the Rhine valley. It consists of limestone- and marl-rich sediments that were deposited in a shallow sea in the period from 250 to 65 million years ago.

During a late phase of the alpine orogeny, the Helvetic sediments were removed from the crystalline bedrock due to pressure from the African continental plate advancing from the south. They were thrust over the existing rock mass up to a distance of 50 kilometres to the north-west where they form thick stacks of nappes today.

The Churfirsten is an imposing example of the nappes of the Helvetic Zone. Image: Nagra

Crystalline – Central and Southern Alps

Crystalline rocks form the visible basement in the southern half of Switzerland. Pressure from the rising of the Alps resulted in strong deformation of the rocks in the alpine belt.

The African and Eurasian plates collide in the Alps. The African plate has been moving northwards over the last 130 million years and is pushing against the Eurasian continent. The rocks are deformed and folded by the immense pressure and the Alps are still uplifting today by one to two millimetres per year. This uplift is partly balanced by erosion. 

Sidelhorn

Granite landscape in Central Switzerland. The dome in the centre of the picture was rounded by the action of glacier ice, while the peaks in the background have retained their sharp edges. Image: Nagra

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