Topical - Geological heritage cal setting beginning with the Proterozoic granodiorite, which was an island surrounded by ocean during the Cretaceous age; the erosion of that granodiorite produced sand, which was deposited along the coast (Figure 7a) and later compacted by more overlaying sand, thus becoming sandstone. Volcanic activity in Tertiary times brought the basaltic magma breaking through the fissures of the granodiorite and the sandstone (Figure 7b). The development of the basaltic columns near the surface and vertical to the cooling surface and reasons for their form and extent could be explained. Even the basaltic hill in a flat terrain tells a story about the weathering and erosion of older but weaker stones around the basaltic cupola – an example of an inverted relief (Figure 7c). Another story could be told about geoscience history and Alexander von Humboldt: in 1789, when he was a student in Bonn, he visited the “Unkelsteine” in the Rhineland, one of the most prominent basalt occurrences in Germany and source of the basaltic columns originally used in the geological wall. After the visit he took part in the dispute between the “Neptunists” and the “Plutonists” about the origin of the genesis of these columns and took up the position of the Neptunists explaining their genesis by the gradual drying of a marine sediment (https://de.wikipedia. org/wiki/Unkelstein). But not only history could be taught. Geological topics like drinking water, soil, energy and raw materials were part of our daily lives 100 years ago and they are part of it even today. Where and in which form do our raw materials occur? How could
we extract them? What do we need for “clean” energy or for electric cars? These issues are not taught – or only randomly taught – at school. The geological wall offers many possibilities to introduce into these subjects. Even if it were for this reason only, it is necessary to make every effort for the protection, renovation and didactical modernisation of the wall. The Geological Wall through the ages and now The wall has been altered, partly when it was moved to its current location and also due to the varying people in charge of it through time. Two main parts (salts and Cenozoic strata) are missing, some stones were lost to weathering or vandalism, some stones were substituted or improperly replaced and numbers got lost. From time to time, the surface has been cleaned with varying degrees of professionalism. Associated explanation plates and labels have disappeared. Nowadays the wall is widely accepted by the authorities and the public. The geological survey of Berlin, the non-profit association of regional geologists (GBB) and the GrünBerlin GmbH association, which is responsible for the whole park, are paying attention to this attraction. Several measures have taken place during the last six years: professional mapping of stones, moss, joint mortar, defects and weathering damages, renovation of the packing, professional surface cleaning, partial replacement of missing stones and revision of the numbering. These measures were carried out by restorers,- restoration students of the
University of Applied Sciences Potsdam in accordance with the agreement of monument protectors. The Federal Institute for Geosciences and Natural Resources (BGR) possesses a number of stones and fossils from historical outcrops in its geoscience collection and provided some for replacement. An interactive digital model of the wall with explanations of the stones has been developed (http://geowand.gruenberlin.de/). The work was crowned with first success by the certification of the status of a “German National Geotope” in 2018. This award has outstanding importance because it acknowledges a geotope in a city of nearly four million people. Concepts for further restoration, re-creation of the lacking parts and explanations (both on the spot and digital) have already been developed and will be realised in the next few years, depending on the funding provided. All involved parties and persons are very committed to a quick and appropriate realisation of the renovation and modernisation concept for the Geological Wall. The teaching of geological knowledge forms the base for understanding complex natural interactions and the attentive use of our natural resources. It should be involved into the school curriculum and could be taught directly in situ at the real natural stones of this fantastic, unique, historical but yet modern Geological Wall. Location: Botanischen Volkspark Blankenfelde, Blankenfelder Chaussee 5, 13156 Berlin, Germany. http://geowand.gruen-berlin.de https://www.berlin.de/senuvk/umwelt/ wasser/geologie/
References Cerny, I. 1989. Die karbonatgebundenen Blei-Zink-Lagerstätten des alpinen und außeralpinen Mesozoikums – Die Bedeutung ihrer Geologie, Stratigraphie und Faziesgebundenheit für Prospektion und Bewertung (The carbonate hosted Pb-Zn deposits of Alpine and non-Alpine Mesozoic - the role of geology, stratigraphy and facies in exploration and valorisation). Archiv für Lagerstättenforschung der Geologischen Bundesanstalt, 11: 5-125. Engel, H., Jersch-Wenzel, S. & Treue, W. 1990. Geschichtslandschaft Berlin – Orte und Ereignisse (History of Berlin – Places and Events), Vol. 3: Wedding, p. 8; Nicolai: Berlin. Geowissenschaftler in Berlin und Brandenburg e.V. (Ed.) 2016. Geologische Wand im Botanischen Volkspark Pankow-Blankenfelde (Geological Wall in the Botanical Park in Pankow-Blankenfelde). Brochure. Wutzke, U. & Liebram, C. 1999. Die Geologische Wand in Berlin und ihre Geschichte (The Geological Wall in Berlin and its History). Geohistorische Blätter, 2(1). p. 19-2. Zache, E. 1896. Die Geologische Wand im Humboldthain zu Berlin (The Geological Wall in the Humboldthain in Berlin). P. Stankiewicz‘ Buchdruckerei: Berlin.
European Geologist 48 | November 2019
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