Elbe sandstone
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Elbe sandstone refers to sandstones whose natural occurrence is limited to the north of Bohemia and parts of Saxony in the greater Dresden area. It is named after the Elbe , which runs through its distribution area in a breakthrough valley , the Elbe valley zone . It is most noticeable in the Elbe Sandstone Mountains , which are divided into Saxon Switzerland on the German side and Bohemian Switzerland on the Czech side. The term Elbe sandstone is used in both geological and economic contexts.
Geological term
Elbe sandstone in the geological sense summarizes all types of sandstone that occur in the Elbe Chalk area and were created in the Cretaceous period . It consists mainly of quartz grains that are bound together in a pebble manner. The proportions and contents of mineral accessories are different. Its deposits are adjacent to the areas of the Lusatian massif (Lusatian anticline), the Meissner massif , of gneiss of the eastern Ore Mountains , in the Elbe Valley Slate Mountains and in the area of the Czech Republic to the north-eastern foothills of the Czech Central Mountains and border zone of Eger Graben .
Petrography of mined Elbe sandstones
The vast majority of the varieties extracted in quarries are sandstones with a pebble grain bond. These are quartz sandstones, the quartz grains of which have intergrown crystal systems due to the solidification ( diagenesis ) at their contact zones. Feldspar , glauconite and iron minerals of the limonite complex are found as secondary components . Fine-grained portions of the minerals illite , kaolinite and quartz are located in the spaces between the pores of the cotta- type sandstone . The kaolinite comes from the decomposition of feldspar ( kaolinization ). The SiO 2 released in the process contributed significantly to the mutual growth of the grains of sand. The pore spaces of the Posta- type sandstone contain largely no fillings.
Reinhardtsdorf's sandstone is a Cotta- type stone with some Posta- type properties .
In the past, sandstones with a carbonate content were broken in a few quarries that are now closed . They come from near-surface deposits and have only been of minor economic importance.
The most important properties of these types of stone are determined by their existing or missing fine grain proportions.
Types of stone
Solidified sand sediments of marine origin from the Upper Cretaceous form a sequence of several layers up to 400 meters thick. They have been mined for centuries and used as stone. The lowest-lying, stratigraphically oldest stone horizon is referred to as a central cuboid or Cotta sandstone , was created in the lower Turon and is often used as a sculptural stone .
Above it lies the upper cuboid formed in the middle Turon, which is also known as Reinhardtsdorfer sandstone . It makes up the bulk of the Elbe sandstone. Reinhardtsdorfer sandstone was and is used in the Dresden Zwinger; In the recent past, the Braunschweig castle was rebuilt with this stone. Similar to it, but of special quality, is the Grillenburg sandstone , which does not come from Saxon Switzerland, but from the place of the same name in the Tharandt Forest near Dresden , like the Hetzdorfer and Niederschöna sandstone, belongs to the Niederschöna layers , which also because of their origin within the Elbe Chalk are considered Elbe sandstones. These sandstone varieties are no longer mined.
The top, youngest layer is called Überquader or Postaer sandstone and, like the similar Wehlener sandstone, occurs only on the right side of the Elbe. This variety, which originated in the upper Turon, has a high degree of strength and is used as a building block , especially in a supporting function. Among other things, it was used in the construction of the Dresden Frauenkirche . The sandstone from the Paulsdorfer , Höckendorfer and Dippoldiswalder Heide , not far from Dippoldiswalde near Dresden, is similar to it .
Portal in Dresden's old town ( White Lane ), sandstone type Posta
Bas-relief at the Jakobikirche in Chemnitz , sandstone type Posta
Main entrance of the Palucca School Dresden , door frames in sandstone of the Cotta type
Architectural jewelry in Chemnitz, sandstone of the Cotta type
transport
For one of the main extraction sites, the quarries in Lohmgrund south of Pirna, the Pirna – Großcotta railway line was built. Many quarries in the Elbe valley between Pirna and Tetschen were able to transport their products either with the Elbe shipping or on the Dresden – Děčín railway line .
Individual evidence
- ^ Siegfried Grunert: The Elbe sandstone: occurrence, use, properties . In: Geologica Saxonica Journal of Central European Geology 52/53 (2007).