Aqueduct marble
Aquäduktenmarmor even channel marble or Eifel marble called, is one of the limestone -scoring local deposits of travertine , whose emergence as a sedimentary rock is ultimately a result of human construction. This makes it unique as a natural stone in Germany. It was created over a period of 190 years as a deposit in the approximately 95 km long walled Eifel aqueduct . The canal, which the Romans built, led from the northern Eifel to Cologne until it was destroyed and was fed by five calcareous springs in the Sötenicher Kalkmulde area, which is known as regional geological .
At Roderath in the Eifel, a natural stone, also known as Eifel marble, is broken. It is a dense, reddish limestone. The use of the term aqueduct marble avoids this possibility of confusion.
Origin and description of the rock
After Cologne became the governor's seat of the Roman province of Lower Germany around 90 AD, an existing long-distance water supply from 30 AD was expanded to a length of 95.4 kilometers. Until it was destroyed by the Franks in the middle of the 3rd century, around 20 million liters of water flowed to Cologne every day through the “Roman Canal”. The Eifel aqueduct was built from Roman concrete ( Opus caementitium ) and natural stones. Their cross-section is about 70 centimeters in width and 100 centimeters in height. The canal was plastered using hydraulic lime with the addition of latent hydraulic substances, such as pozzolan from the Eifel as ground Eifeltuff or with brick chippings and thus sealed. The brick chippings are responsible for the red color of the plaster. The Roman Canal was about a meter underground and was thus protected from frost.
The water flowing through the Roman Canal was calcareous and the lime was deposited in layers on the walls and bottom of the canal. The deposition process is known as sintering . As a result of the separation (precipitation) of lime dissolved in water and iron oxides transported in the water, crusts - so-called sintered lime - formed in the form of parallel corrugated deposits with a thickness in the range of centimeters and up to about 30 centimeters.
The iron minerals like hematite and limonite are responsible for the reddish and brownish color. If the iron compounds were missing, the crust settled lightly and there was a color change in the rock. The lime and carbon dioxide-containing water slowly loses both components when it escapes to the surface of the earth. The famous sintered terraces at Pamukkale are the result of the same chemical process.
The resulting lime oversaturated water precipitates so much lime that the degree of saturation is reached again. Before the water pipes were destroyed, a dense limestone sinter up to a thickness of about 30 centimeters was deposited within 190 years. Special chemical and physical circumstances of the water sources and the course of the Roman aqueduct led to the particularly attractive formation of stone, which we now call onyx marble . Petrographically it is a limestone, especially a lime sinter. In other cases, such as on the Pont du Gard near Nîmes , such limescale deposits have only produced a porous limestone.
The reddish to brownish and white striped Eifel marble deposited in the canal is visually similar to onyx marbles or so-called cipollinos and can be polished. The differently colored layers of deposits give the stone an attractive appearance. In contrast to other travertines , which are highly porous, this one is relatively dense. After the line had been destroyed by the Franks in the course of the " Imperial Crisis ", by 280 AD at the latest, it was not rebuilt in late antiquity , and so the canals fell into disrepair and became a quarry since the Carolingian era and later utilized. There are no other occurrences of aqueduct marble.
use
Due to its limited stone sizes only single pieces such as columns, were prepared from Aquäduktenmarmor, Epitaphe , covers a Tumba and altar tabletops.
This sintered lime was probably the first time for those of Charlemagne built Palatine Chapel of Aachen used.
In the 11th to 13th centuries, several Romanesque chapels in Cologne were decorated with aqueduct marble. At the St. Cäcilienkirche (today Schnütgen Museum) there are eight columns made of this stone in the choir outside, in the west choir of St. Georg numerous 2.76 meters long columns of this type are built, St. Maria Lyskirchen shows at the stairs to the gallery two 1.36 meters long such columns, the church of St. Nikolaus in Cologne-Dünnwald also has two sintered lime columns that support the cross vault. The St. Michael church in Cologne-Porz-Niederündorf has an epitaph from this lime sinter. In Cologne Cathedral there are two grave cover plates from the Eifel measuring 1.91 × 0.65 meters that have broken.
The two front columns of the canopy above the high altar of the Maria Laach Abbey are made of sintered limestone, and numerous churches in the mining area also have individual stones made of aqueduct marble. Further art objects made from this material can be found in Drolshagen, Essen, Soest, Hildesheim, Paderborn and Helmstedt. At the Wartburg , 25 of the 200 columns that were once preserved can be viewed. These are located on the first and second floors in the inner arcades and have survived the centuries because the arcades were walled up as early as the 14th century. The landgraves of Neuchâtel also had imported columns made of aqueduct and Lahn marble . At the Dankwarderode Castle in Braunschweig there are two chimneys with four columns made of Eifel marble, as well as two slabs set into the wall.
In Canterbury , England, there is a small altar plate made from this stone. The grave slabs of Estrid, King Sven and Bishop Wilhelm in Roskilde Cathedral are made of aqueduct marble. The Chapel of the Holy Cross in Dalby , the oldest stone church in Sweden, has a column made of this rare stone.
literature
- Klaus Grewe : The Eifel aqueduct. Aqueduct for the Roman Cologne and quarry for the Romanesque large buildings. Cologne 1977.
- Klaus Grewe: The Eifel water pipeline to Cologne. From the Roman aqueduct to the quarry for Romanesque buildings. In: Die alte Stadt 4/2004, p. 247 ff.
- Klaus Grewe: Aqueduct marble. Lime sinter of the Roman Eifel aqueduct as a building material of the Middle Ages . In: Bonner Jahrbücher Volume 191, 1991, pp. 277–246.
- Dieter Klaua: Lime sinter - a special building material for columns on the Wartburg. In: Wartburg yearbook 1994, p. 49 ff.
Web links
Individual evidence
- ↑ The term aqueduct marble is used by Klaus Grewe, who researched the technology, planning and routing of the Roman water pipes to Cologne and received the Frontinus Medal for this in 1988.
- ^ Grewe: The Eifel water pipeline to Cologne . P. 254 and 250 (see literature).
- ^ Grewe: The Eifel water pipeline to Cologne . P. 257f. (see literature).
- ^ Grewe: The Eifel water pipeline to Cologne . P. 258 (see literature).
