Bernese sandstone
The Bernese sandstone is a sedimentary rock that has been used on numerous buildings in Switzerland , in the Bern area and above all in the old town of Bern . It is of great cultural and historical importance for Switzerland. The rock was formed in Miocene 25 million years ago in the molasses of erosional debris of the Alps in a shallow sea .
Rock description and mineral inventory
This sandstone is a gray rock with color tendencies towards olive green or blue-green and yellow, depending on the quarrying site. The different green tones of the rock depend on the degree of oxidation of the mineral glauconite . On this sandstone, sedimentary structures such as cross layers and ripple marks can be seen , which are particularly evident during weathering processes .
The diameter of the quartz grains is predominantly 0.1 to 0.4 millimeters and occasionally even larger. This sandstone consists of 55 to 65 percent quartz , 20 to 25 percent feldspar , 20 to 25 percent rock fragments and 2 to 4 percent other heavy minerals.
use
From a technical point of view, Bernese sandstone is a soft stone . Because of its low grain binding, it is "soft" and therefore relatively easy to work with stonemason and stone carving tools. Due to this fact, it was often used as a building block and is still used by stone carvers for sculptures to this day . The old town of Bern , which was badly damaged after the great fire of 1405, was rebuilt with this natural stone in order to minimize the risk of fire. The Kornhaus , the Heilig-Geist-Kirche , the Zytglogge and the Burgerspital in Bern, for example, are made of this native gray-green natural stone. The entire natural stone ensemble in Bern's old town is part of the UNESCO World Heritage Site .
The most representative building with a facade made of this stone is the Bundeshaus . Although the architect Hans Wilhelm Auer was critical of the use of this sandstone because of its rock-physical properties, he tried to ensure that a careful selection was made. Deliveries were used in a targeted manner according to his specifications so that they could develop a conscious color effect in the overall picture of the facade with their own color tones. The ashlar masonry above the base on the north facade consists of the Harnischhuter sandstone (gray), on the south side the Ostermundiger sandstone (gray) in courtyards and at galleries the Stockernstein (yellow). Other Swiss rocks were used for ledges, balustrades and column capitals and bases because they are more resistant to the weather. This resulted in additional colored detail effects in the predominantly gray-looking facade of the Federal Palace.
From the middle of the 19th century, numerous structures made of Bernese sandstone were built. At the time of this strong demand, this rock material was mined from weathered and inferior rock layers. In addition, the low weather resistance of the Bernese sandstone was added. Therefore, numerous stone facades had to be replaced or repaired after a short time. The upper part of the tower of the Bern Minster was therefore made in the 19th century from the more weather-resistant Obernkirchen sandstone . Today the Bernese sandstone is clearly used in the preservation and replacement of historical buildings.
Bernese sandstone was mainly used for solid buildings, as masonry or for ornamental or stone carving work. It is also used for garden designs, exterior facades and floor coverings.
Occurrence and mining
The sandstone that is mined in Ostermundigen , Krauchthal and am Gurten is now known as Bern sandstone . This sandstone has been quarried in Ostermundigen and on Gurten, in the south of Bern, since the 15th century. The so-called blue sandstone is broken on the Gurten . The width of the geological sandstone strip is between 5 and 15 kilometers and it stretches from Schaffhausen to Lausanne . The occurrence around Bern reaches its greatest thickness . The occurrence extends from there to the west of Freiburg .
An original quarry in Ostermundigen was the largest quarry in Switzerland in the middle of the 19th century. From 1871 to 1902 a 1.5 km long connecting railway, which was equipped with a rack system Riggenbach, ran from the work place at the quarry to the train station. This railway was the first cog railway in Switzerland and one of the first in Europe. There is an actively operated quarry in this place where a blue and yellow type is quarried.
There is a sandstone educational trail in the village of Krauchthal and in the surrounding area there are caves and shelters in the sandstone walls. In the so-called “Giraffe” sandstone formation on the Sandsteinflühe, there are houses embedded in the rock that have been inhabited since the 16th century, the so-called Fluehüsli .
Modern stone extraction in the quarries is carried out with wire saws , which saw raw blocks from the walls of the quarry with diamond-studded ropes or with cutting machines . In Krauchthal, Bernese sandstone is mined vertically down below the soil surface.
Around 1.5 million cubic meters were extracted from the Bernese sandstone, which has been mined for around 800 years.
literature
- Toni P. Labhart: Steinführer Bundeshaus Bern , Swiss Art Guide GSK, Volume 719, Bern 2002. ISBN 3-85782-719-X
- F. de Quervain: The usable rocks of Switzerland. Kümmerly & Frei, Bern 1969
- Hansueli Trachsel: Sandstone: A surprising variety. Stämpfli publishing house. Bern 2006. ISBN 3727211113
Web links
- Surface of the Bernese sandstone blue
- Surface of the Bernese sandstone yellow
- Technical data of the Bernese sandstone
Individual evidence
- ↑ Quervain: 1969, p. 213
- ↑ http://www.von-dach.ch/sandstein.html data on www.von-dach.ch
- ^ Toni P. Labhart: Steinführer Bundeshaus Bern , 2002
- ↑ Use of the Bernese sandstone in the garden ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. (PDF; 363 kB)
- ↑ Information on www.diedutt.de
- ↑ Dirk Dethleff: Swiss sandstone - geology, mining and use. January 2001. Edited by the Swiss working group Pro Naturstein. Available online ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
- ↑ History of the Ostermundigen quarry ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
- ↑ Steiger, Peter: “The very first cogwheel locomotive drove in Ostermundigen”. In: Berner Zeitung. Status: February 27, 2012. [1] , accessed November 16, 2014.
- ↑ Living under mighty sandstone formations
- ↑ Toni P. Labhart: The stones of Bern . TU Berlin: Applied Geosciences. Stones in the city. Workshop 2009 ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
