Recreation and edification in the Siebengebirge (seven mountains area) – of a landscape that is 400 million years old

“The canyon that is full of reliefs, and recesses deeply, of the central Rhineland ends in a fortissimo with the Siebengebirge before a river landscape extends to form the sedate largo of the Lower Rhine bay lowlands”. This is how it is described in the new volume of "Das Siebengebirge – Natur, Landschaft, Kultur" (The seven mountains – nature, landscape, culture) that conveys a lot of worthwhile information (Wienand Verlag Cologne 2002). It becomes clear due to the musical metaphors that the Siebengebirge viewed as the Rhine flows down river marks the final fanfare of that dramatic landscape, which begins in Bingen and ends in Bonn.

 Viewed from close quarters the Siebengebirge represents an independent, clearly distinct landscape unit as a natural space. More than forty elevations, the seven most famous of which are Drachenfels, Petersberg, Wolkenburg, Löwenburg, Nonnenstromberg, Lohrberg and Ölberg characterise the landscape. It is possible that the name is derived from these seven hills, but it could also stem from the German term Siefen (for valleys that deepen like a gorge). The striking volcanic summits and peaks form the ideal backdrop of a romantic landscape, which has enchanted generations of sentimental travellers. However the very specific character of this landscape is not just due to its surface but also due to its interior life that can occasionally still be viewed from the outside as well as its subsoil: It can tell you dramatic things of a past extending over millions of years. For example that the Siebengebirge area was once a tropical coast landscape…

400 million years ago a flat stretch of water extended across the area of the current Rhineland slate hill range – comparable to the dimensions of the Mediterranean Sea. Thus a great deal of fossilised marine creatures were recently found during the construction of the tunnel tubes for the Frankfurt / Cologne ICE line: Mussels, feather stars, Crustacea triloba, armed gurnards … For a time an extensive amount of coastline vegetation also spread out here that was similar to the salt marshes on the edge of the North Sea coast. Later a shift to the side reformed the layers that had originally been deposited horizontally to form close successions of waves and arches, resembling a creased table cloth. And this folding of the mountains continued for almost one hundred million years. Hot solutions of mineral compounds could repeatedly penetrate into the stone clefts that were created during the folding process, which in some cases separated themselves as gangues during the cooling process. These ore deposits were later to form the basis of a mining tradition in the Siebengebirge that lasted several hundred years. Lead, zinc and copper ores were extracted in the Einsiedlertal and in the Schmelztal extending into the 20th century. But we don't want to jump ahead of ourselves .....

Comparatively little happened from the end of the Paleozoic age until the start of the Cenozoic age if we disregard the fact that the folded mountains shrank to become a folded trunk in this period of approx. 220 million years. But then a few million years later, the scenery took on a completely new appearance: Powerful volcanic eruptions provided the Siebengebirge with its characteristic summits and peaks. Scientists know of more than 300 eruption points. And this fiery spectacle began approx. 25 million years ago.

The British diplomat Sir William Hamilton was the first to recognise the volcanic nature of the Siebengebirge on his trip to the Rhine in 1722. As an ambassador at the court of Naples he once witnessed an eruption of Mount Vesuvius. Today we know that even more volcanic landscapes emerged in this environment. The volcanic mountains from the area surrounding the Laach lake were created less than 50,000 years ago. The Rodderberg on the left hand bank of the Rhine near Mehlem is even younger: It erupted just some 35,000 years ago….

But we shall now go back in time again: Volcanic activity was very widespread in the Siebengebirge area for approx. seven million years, its manifold reliefs amongst other things tends to suggest that this landscape was not created in one volcanic event. Subject to enormous excess pressure trachyte tuff was hurled from the earth’s interior, the most well known trachyte summit in the Siebengebirge is the Drachenfels (Dragon’s rock). In the next fiery phase latite tuff was ejected, then later basalt tuff was projected from the earth's interior as specific heavier proportions from the magma chambers. Incidentally columnar basalt is broken as a square hewn stone near Linz to this day.

The volcano summits of the Siebengebirge were used as a stone bridge for centuries and provided construction material for Roman camps and also for medieval castles and churches. Cologne cathedral has for the most been built using trachyte, whilst the Heisterbach Cisterician Abbey was built from latite.

The high quarrying walls, which now bear testimony to the intensive quarrying activities - have despite spoiling the landscape still also made it possible to gain unsuspected insights into the area's geological history and also now fascinating geological spectacles for interested tourists - such as the former basalt quarry at Großer Weilbruch, the former quarry at Stenzelberg or the abandoned quarry on the north western flank of the Lohrberg.

Upon closer inspection of the cultural landscape of the Siebengebirge with its mixed forests, vineyards and orchards the former quarries prove themselves to be an essential piece of the jigsaw. These interventions within the natural landscape have created ecological niches, which are used by new plant and animal species. Thus yellow bellied toads have, for instance, found a home for themselves in the inaccessible quarry lakes. And in caves that have been created by the mining of trachyte tuff rare bat species have found places where they can hibernate. Although the Siebengebirge appears to be a very natural and unspoilt area human actions have left their mark here since the Neolithic Age. Following these marks is a wonderful experience that locals and visitors from other areas have treated themselves to for generations.

The Siebengebirge has had a tried and tested role as a recreational area since the burgeoning era of Rheinromantik (Rhine Romanticism). Even as long ago as the latter half of the 19th centuries scenic improvement societies set about their work, stopped quarrying, created the tourist infrastructure whilst using technical innovations - one also has to think of the rack railway to the top of the Drachenfels - built hiking trails and made it possible for broader sections of the public to enjoy the natural environment.

As early as 1836 the Drachenfels was protected against economic exploitation at the intervention of the King of Prussia to ensure the preservation of the memorable ruin at its summit and the picturesque cultural landscape. Almost one hundred years later the Siebengebirge was proclaimed as one of the first German nature reserves by means of the declaration of 20 January 1923 after the state had issued its authorisation for the identification of nature reserves in 1920 and the protection of monuments of art, history and the natural environment had been stipulated as a state task in Section 150 of the imperial constitution of 1919. The Siebengebirge has been a place of recreation and edification for two centuries, and people were already endeavouring to preserve this beauty for forthcoming generations some time ago.

Now the Siebengebirge nature park has been wonderfully well developed as a recreational area and is accessible from numerous car parks for hikers – it is a fascinating experience for people interested in the geology, natural history and cultural history.