The diverse rocks of Switzerland


Switzerland has igneous, sedimentary and metamorphic rocks. These three rock types are closely connected to each other in a cycle.

Rocks are formed, altered and then break down again in a continuous cycle. Three types of rocks are part of the cycle: igneous, metamorphic and sedimentary rocks. Rocks basically consist of mineral components, which also include natural glasses. They can also contain originally organic material such as animal remains or plant components. Learn more about Switzerland’s rocks in the following sections.

In the rock cycle, a cycle progresses over a geological period of several hundred million years. A fraction of this is the time period relevant for the disposal of radioactive waste: safety analyses for a deep geological repository for high-level waste “only” have to be made for a period of one million years. During this period, the waste must be contained in stable rock layers underground – to protect people and the environment.

In order for Nagra to safely store the waste underground, it needs in-depth knowledge of the suitable rocks and their properties. In Switzerland, the clay rock Opalinus Clay is suitable for a deep geological repository. It has been thoroughly researched. You can learn more about the Opalinus Clay and other rocks on a guided tour through the Swiss underground rock laboratories.

The rock cycle

The rocks within the uppermost 30 to 60 kilometres of the earth, the earth’s crust, are in a continuous cycle.

These cyclical movements are mostly so slow that we are not aware of them. Mountains form, and the rocks exposed at the surface are weathered. The mountains are eroded, and the debris is carried off in rivers and deposited elsewhere. Sedimentary rocks are formed from the eroded material.

All rocks can reach great depths where they melt or are altered to form metamorphic rocks. The molten rock, or magma, solidifies at depth or at the earth’s surface as magmatic rock, and the cycle begins anew.

Rocks form in a slow cycle between the earth

1. Igneous rocks

When magma cools in the earth’s crust, it solidifies to form plutonic rocks such as granite. Magma from volcanoes that reaches the earth’s surface is termed lava. This solidifies to form volcanic rocks such as basalt. Some magma also rises from below through narrow dykes and rock fissures. If this magma does not reach the surface and remains and solidifies in the dykes, dyke rocks such as aplite and lamprophyre form as a result.

Basalt columns form due to the delayed cooling of lava. There are no examples of these impressive columns in Switzerland – all the basalts are metamorphic and were overprinted by heat and pressure deep in the earth’s interior. Photo: Nagra

Examples of magmatic rocks in Switzerland


Granite (plutonic)

Habkern granite, Habkern (Canton Bern). Photo: <a href="https://collections.erdw.ethz.ch" data-type="URL" data-id="https://collections.erdw.ethz.ch" target="_blank" rel="noreferrer noopener">Earth Science Collections of the Swiss Federal Institute of Technology Zürich</a>, Urs Gerber’ style=’width:100%’><figcaption></figcaption></figure><p><strong>Occurrence:</strong> Alps, crystalline basement beneath the Swiss Plateau and Jura Mountains<br /><strong>Origin: </strong>Slow cooling of magma at depth, resulting in large interlocking crystals<br /><strong>Main minerals:</strong> Feldspar, quartz, mica<br /><strong>Appearance:</strong> Light, speckled, massive<br /><strong>Properties:</strong> Grainy, very hard, in some locations with joints and dykes<br /><strong>Uses:</strong> Floor and façade tiles, blocks for road and waterway engineering, gravestones</p><hr class="wp-block-separator" /><h4 class="wp-block-custom-heading">Volcanic basalt</h4><figure class=Metamorphic basalt from Alp Flix (Canton Graubünden). Photo: <a href="https://collections.erdw.ethz.ch" data-type="URL" data-id="https://collections.erdw.ethz.ch" target="_blank" rel="noreferrer noopener">Earth Science Collections of the Swiss Federal Institute of Technology Zürich</a>, Urs Gerber’ style=’width:100%’><figcaption></figcaption></figure><p><strong>Occurrence: </strong>Common worldwide, metamorphic in Switzerland<br /><strong>Origin:</strong> Rapid cooling of lava at the earth’s surface, and hence not fully crystallised<br /><strong>Main minerals: </strong>Pyroxene, hornblende, olivine, feldspar<br /><strong>Appearance:</strong> Dark grey to black, massive<br /><strong>Properties:</strong> Sharp-edged, brittle, weathering-resistant<br /><strong>Uses:</strong> Glass wool production, cobblestones</p><hr class="wp-block-separator" /><h4 class="wp-block-custom-heading">Aplite and lamprophyre dyke rocks</h4><figure class=Aplite dyke (light) in gneiss (dark), Bergell (Italy). Photo: <a href="https://collections.erdw.ethz.ch" data-type="URL" data-id="https://collections.erdw.ethz.ch" target="_blank" rel="noreferrer noopener">Earth Science Collections of the Swiss Federal Institute of Technology Zürich</a>, Urs Gerber’ style=’width:100%’><figcaption></figcaption></figure><p><strong>Occurrence: </strong>Solidified magma in rock fissures<br /><strong>Origin: </strong>Rapid cooling of lava at the earth’s surface, and hence not fully crystallised<br /><strong>Main minerals (aplite):</strong> Quartz, light mica<br /><strong>Main minerals (lamprophyre):</strong> Feldspar, hornblende, pyroxene, dark mica<br /><strong>Appearance (aplite):</strong> Light and fairly fine-grained<br /><strong>Appearance (lamprophyre):</strong> Dark and fine- to medium-grained<br /><strong>Properties:</strong> Hard, easily workable<br /><strong>Uses:</strong> Limited use in Switzerland</p><hr class="wp-block-separator" /><h2 class="wp-block-custom-heading" id="sediment">2. Sedimentary rocks</h2><p>Sedimentary rocks are formed from materials (e.g. eroded material from mountains, mud, sand or salt) deposited on land or in the water where they gradually solidify. The originally loose components are cemented together with time to form solid rocks. Sedimentary rocks are often layered. Conglomerates, such as nagelfluh, sandstone and clay, consist of eroded material from mountains. Limestones are formed mainly from shells and other hard parts of sea creatures. Chemically formed sediments, such as gypsum and rock salt, are formed when marine and lacustrine waters evaporate.</p><figure class=New sediments are being formed here. Rivers transport rock debris to the plains where they are deposited. With time, these loose gravel deposits form a solid nagelfluh. Photo: Nagra

Examples of sedimentary rocks in Switzerland


Nagelfluh (conglomerate)

Nagelfluh, Gottschalkenberg (Canton Zug). Because of its appearance, nagelfluh is also called “concrete of the good Lord”. Photo: <a href="https://collections.erdw.ethz.ch" data-type="URL" data-id="https://collections.erdw.ethz.ch" target="_blank" rel="noreferrer noopener">Earth Science Collections of the Swiss Federal Institute of Technology Zürich</a>, Urs Gerber’ style=’width:100%’><figcaption></figcaption></figure><p><strong>Occurrence: </strong>Mainly at the alpine margin<br /><strong>Origin: </strong>In the Alps, rocks are reduced to debris by erosion. Rivers transport this material into the foreland and deposit it in the Molasse Basin<br /><strong>Composition:</strong> Gravels from different alpine rocks (e.g. granite, limestone), cemented and solidified into a fine-grained ground mass<br /><strong>Properties:</strong> Forms ridges and steps in the landscape</p><hr class="wp-block-separator" /><h4 class="wp-block-custom-heading">Sandstone</h4><figure class=Mica sandstone with chestnut leaf, Kreuzlingen (Canton Thurgau) Photo: <a href="https://collections.erdw.ethz.ch" data-type="URL" data-id="https://collections.erdw.ethz.ch" target="_blank" rel="noreferrer noopener">Earth Science Collections of the Swiss Federal Institute of Technology Zürich</a>, Urs Gerber’ style=’width:100%’><figcaption></figcaption></figure><p><strong>Occurrence: </strong>Swiss Plateau and Alps<br /><strong>Origin:</strong> Deposition in river channels and the sea<br /><strong>Composition:</strong> Mainly quartz grains and rock fragments, mostly cemented with limestone<br /><strong>Appearance:</strong> Grey, rarely red, green and yellow, fine-grained<br /><strong>Properties:</strong> Easily workable, often low durability<br /><strong>Uses:</strong> Building bricks, façade tiles, road surfacing, stone masonry</p><hr class="wp-block-separator" /><h4 class="wp-block-custom-heading">Molasse marl</h4><figure class=Molasse marl, Eriz near Thun (Canton Bern) Photo: <a href="https://collections.erdw.ethz.ch" data-type="URL" data-id="https://collections.erdw.ethz.ch" target="_blank" rel="noreferrer noopener">Earth Science Collections of the Swiss Federal Institute of Technology Zürich</a>, Urs Gerber’ style=’width:100%’><figcaption></figcaption></figure><p><strong>Occurrence: </strong>Swiss Plateau and alpine margin<br /><strong>Origin: </strong>In river plains and the sea<br /><strong>Composition:</strong> Very fine-grained mix of calcite, clay and other mineral and rock grains<br /><strong>Appearance:</strong> Multi-coloured, layered<br /><strong>Properties:</strong> Mostly dense, soft after weathering at the earth’s surface<br /><strong>Uses:</strong> Brickwork products</p><hr class="wp-block-separator" /><h4 class="wp-block-custom-heading">Clay</h4><figure class=Opalinus Clay from the Mont Terri Rock Laboratory (Canton Jura) Photo: <a href="https://collections.erdw.ethz.ch" data-type="URL" data-id="https://collections.erdw.ethz.ch" target="_blank" rel="noreferrer noopener">Earth Science Collections of the Swiss Federal Institute of Technology Zürich</a>, Urs Gerber’ style=’width:100%’><figcaption></figcaption></figure><p><strong>Occurrence: </strong>Jura and northern parts of Switzerland and the Alps<br /><strong>Origin:</strong> Deposition in the sea<br /><strong>Composition:</strong> Clay minerals, quartz, little calcite<br /><strong>Appearance:</strong> Varicoloured, often layered<br /><strong>Properties:</strong> Soft, dense; clay minerals swell on contact with water<br /><strong>Uses:</strong> Sealing clay for disposal sites and dams, production of clay bricks and cement</p><hr class="wp-block-separator" /><h4 class="wp-block-custom-heading">Limestone</h4><figure class=Öhrlikalk, Öhrlisattel (Canton Appenzell Innerrhoden). Photo: Collection Urs Oberli, St. Gallen

Occurrence: Jura and Alps
Origin: Deposition of hard parts of organisms on the sea floor
Composition: Mainly calcite
Appearance: Mostly light- to blue-grey, fine-grained
Properties: Easily workable
Uses: Floor tiles, building bricks, cement production, lime plaster


Anhydrite and gypsum

Anhydrite between clayey shale (below) and gypsum (above), Simplon Tunnel (Canton Valais). Photo:<a href="https://collections.erdw.ethz.ch" data-type="URL" data-id="https://collections.erdw.ethz.ch" target="_blank" rel="noreferrer noopener"> Earth Science Collections of the Swiss Federal Institute of Technology Zürich</a>, Urs Gerber’ style=’width:100%’><figcaption></figcaption></figure><p><strong>Occurrence:</strong> Tabular and Folded Jura, Alps<br /><strong>Origin:</strong> Precipitation from seawater due to evaporation<br /><strong>Main minerals: </strong>Gypsum and anhydrite; gypsum contains confined water, anhydrite is anhydrous<br /><strong>Appearance:</strong> White to dark-grey, coarse-grained, banded<br /><strong>Properties</strong>: Soft<br /><strong>Uses:</strong> In the construction industry as gypsum plaster, special gypsum, plasterboard, production of cement and porous concrete, modelling and moulding plaster, production of sulphuric acid</p><hr class="wp-block-separator" /><h2 class="wp-block-custom-heading" id="metamorphe">3. Metamorphic rocks</h2><p>Increased pressure and temperature deep underground result in the transformation of all types of rocks to metamorphic rocks by changing their structure or composition. This can lead to the formation of new minerals that grow in a preferred direction, namely perpendicular to the largest pressure component.</p><figure class=Metamorphic rock structures at the Grimsel Test Site. Photo: © Comet Photoshopping, Dieter Enz

Examples of metamorphic rocks in Switzerland


Gneiss

Gneiss, Central Alps. Photo: <a href="https://collections.erdw.ethz.ch" data-type="URL" data-id="https://collections.erdw.ethz.ch" target="_blank" rel="noreferrer noopener">Earth Science Collections of the Swiss Federal Institute of Technology Zürich</a>, Urs Gerber’ style=’width:100%’><figcaption></figcaption></figure><p><strong>Occurrence: </strong>Alps, crystalline basement beneath the Swiss Plateau and Jura Mountains<br /><strong>Origin:</strong> Rock altered by increased pressure and temperature, produced from granite for example<br /><strong>Main minerals:</strong> Feldspar, quartz, mica<br /><strong>Appearance:</strong> Light speckling, thick-layered with augen structure due to orientation of minerals<br /><strong>Properties:</strong> Weathering-resistant, fissile. Can be strongly fractured and penetrated by dykes<br /><strong>Uses:</strong> Kerbstones, building bricks, floor and façade tiles, roofing</p><hr class="wp-block-separator" /><h4 class="wp-block-custom-heading">Schist</h4><figure class=Hornblende-Garbenschiefer, Val Tremola (Canton Ticino). Photo: <a href="https://collections.erdw.ethz.ch" data-type="URL" data-id="https://collections.erdw.ethz.ch" target="_blank" rel="noreferrer noopener">Earth Science Collections of the Swiss Federal Institute of Technology Zürich</a>, Urs Gerber’ style=’width:100%’><figcaption></figcaption></figure><p><strong>Occurrence:</strong> Alps, crystalline basement beneath the Swiss Plateau and Jura Mountains<br /><strong>Origin:</strong> Metamorphosis of clay-rich parent rock<br /><strong>Main minerals:</strong> Mainly mica with a variety of other minerals<br /><strong>Appearance:</strong> Shiny, dark, thin-layered due to mineral orientation<br /><strong>Properties:</strong> Easily fissile along smooth cleavage planes<br /><strong>Uses:</strong> Floor and façade tiles, roofing</p><hr class="wp-block-separator" /><h4 class="wp-block-custom-heading">Marble</h4><figure class=Marble, Central Alps. Photo: <a href="https://collections.erdw.ethz.ch" data-type="URL" data-id="https://collections.erdw.ethz.ch" target="_blank" rel="noreferrer noopener">Earth Science Collections of the Swiss Federal Institute of Technology Zürich</a>, Urs Gerber’ style=’width:100%’><figcaption></figcaption></figure><p><strong>Occurrence:</strong> Alps<br /><strong>Origin:</strong> Transformation (metamorphosis) of limestone and dolomite<br /><strong>Main minerals:</strong> Calcite (lime marble), dolomite (dolomite marble)<br /><strong>Appearance:</strong> Grainy, light, partly banded<br /><strong>Properties: </strong>Easily workable<br /><strong>Uses:</strong> Floor and façade tiles, tiling, sculptures</p><hr class="wp-block-separator" /><h3 class="wp-block-custom-heading">More information</h3><p><strong>Nagra</strong>:</p><ul class=
  • “Stein” (pocket-sized hardcover book on Switzerland’s rocks (in German))

  • Brochure “Erosion”

  • Geology of Switzerland

  • Nagra blog

  • Additional information sources: