Geopark Thuringia Inselsberg - three equals

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Logo of the Geopark Thuringia Inselberg-Drei Gleichen

The GeoPark Inselsberg - Drei Gleichen is a geopark in Thuringia . It covers parts of the Thuringian Forest and the southern foothills of the Thuringian Basin on an area of ​​about 600 km² . It touches the area of ​​18 municipalities (7 of which are cities). On February 15, 2008 the Geopark Inselsberg - Drei Gleichen was awarded the title “National GeoPark in Germany”.

Location and description

The GeoPark Inselsberg - Drei Gleichen covers the western part of the Thuringian Forest with its northern foreland as a transition area from the low mountain range to the flat, undulating arable plains of the Thuringian Basin. It is bounded by several cities, in the east by Erfurt and Arnstadt , in the north by Gotha , in the south by Ohrdruf and Schmalkalden and in the west by Eisenach and Bad Salzungen . Main hiking and cycling trails such as the Rennsteig , the Thuringian Path and the Thuringian City Chain (part of a European cycle path) lead through the area of ​​the Geopark.

One of the namesake of the Geopark is the Inselsberg (916 m above sea level) in the Thuringian Forest. On the other hand, the Geopark got its name from the castle ensemble of the " Drei Gleichen ", formed from the medieval castles Mühlburg , Wachsenburg and Gleichen , which are in close proximity to each other.

geology

The Geopark is divided into three natural units: the western Thuringian Forest (Inselsberg region), a representative part of the southwest Thuringian basin (three equals region) and a small part of the southwest Thuringian Triassic landscape. In the Inselsberg region, all rocks from the Ruhlaer Kristallin to the Rotliegend are represented in the entire Thuringian Forest . The landscape is determined by the more weather-resistant rhyolite peaks, which are bordered by deeply carved valleys in softer types of rock.

The area of ​​the Drei Gleichen forms part of the Eichenberg – Gotha – Saalfeld fault zone that runs from northwest to southeast . A part of it is the Wachsenburg-Graben. Here the strata of the shell limestone up to the lias are fully exposed in a tightly limited space . In the valley areas, they are covered by the Pleistocene deposits of the Apfelstädt River . In this region, there are also sinkholes ( sinkholes ) and local subsidence areas caused by subsidence. In the area of Wachsenburg trench there are several artesian springs, called Jump from which karst groundwater comes to light. These include the Mühlberger Spring , the Gräfenbrunnen and the salt spring at Sülzenbrücken .

Theme of the geopark

The motto of the National GeoPark Thuringia Inselsberg - Drei Gleichen is "In the footsteps of Pangäa". The rocks and geological outcrops in the Geopark testify to the formation of the supercontinent Pangea and its development from its beginnings to its decay.

340 million years ago, the northern major continent "Old Red Continent", also known as Euramerica, and the southern continent "Gondwana" merged to form the global giant continent Pangea. The enormous geological "weld seam" of this connection is formed by the rocks of the Ruhla Crystalline. It is the oldest rock in the Geopark and is an impressive testimony to the formation of Pangea. The younger layers of the transition storeys and the table top mountains emerged in the center of the giant continent. Every layer surface from the Upper Carboniferous (310 million years ago) to the youngest sections of the table deck mountains, the approx. 190 million year old layers of the Lower Jurassic, represents the imprint of the surface of Pangea. Every living being, whose remains or traces are today as fossils found on the strata, was a resident of Pangea. This applies to a tree-high fern plant of the Rotliegend period as well as to a Ceratit (marine cephalopod) from the sea of ​​the Upper Muschelkalk. About 150 million years ago the Atlantic Ocean broke open between Europe and North America and the final disintegration of Pangea began. In the Keuper there is a striking gap in the layers that shows this breaking up.

The many geological objects in the Thuringian Geopark Inselsberg - Three Equals have one thing in common: They all represent the imprint of a land surface "in the middle of Pangäa".

Significant geotopes and exhibits

The most important inventory of the Geopark are the geotopes . They provide insights into the inner structure and history of the earth's development. Some geotopes from the Geopark Inselsberg - Drei Gleichen are listed here:

  • “Bromacker” primeval dinosaur site near Tambach-Dietharz

The quarries at Bromacker near Tambach-Dietharz are among the most important sites in the world for ancient land-living vertebrates, and the site is unique in Europe. Around 30 years ago, the first bones of these so-called "primeval dinosaurs" were found, which represent a transitional form from amphibians to reptiles.

  • Mühlberger Spring

The Mühlberger Spring is one of the most important karst springs in the central part of the Thuringian Basin. The source feeds the Weidbach , which used to drive up to six mills. For centuries this has been the basis of the water supply in the area and also formed the basis for the settlement of the region.

  • Haarhausen gravel pit

The disused quarry on the southern edge of Haarhausen shows a section of the Wachsenburg moat, which is part of the Eichenberg-Gotha-Arnstadt-Saalfeld fault zone. Here you can clearly see how the originally horizontal rock layers are folded during the mountain formation.

  • Trusetal waterfall and Trusetal main course

The artificial Trusetal waterfall served to drain the Trusetal mining area. It has a fall height of 58 m. The rocks around the Trusetal waterfall are an excellent example of the so-called "wool sack weathering" of granite rock. The granite in this area is intersected by a mixed vein of syenite porphyry and kersantite . Since the corridor was superficially dismantled, it can only be seen today as an open crevice.

  • Oven holes

The oven holes at Bad Tabarz are three parallel caves in the volcanic rock (rhyolite), the origin of which has not yet been clarified. On the one hand, it could be lava tunnels, but so far only known in young basalt rock. On the other hand, the tubes could have been created by water erosion; for such a pseudo-karst, however, the shape would be very unusual. If one of the two theories proves to be true, it would be unique in the world.

  • Marienglashöhle Friedrichroda

The Marienglashöhle is a show mine with a natural crystal grotto, which was discovered by chance by miners in 1778. In the past, Marienglas was mined here and used to decorate altars, chandeliers and images of the Virgin, which is what gave the mineral its name. Marienglas is a variety of plaster of paris. The grotto is a natural monument that is unique in Germany.

  • Altensteiner cave

The Altensteiner Höhle in Schweina is the longest and oldest show cave in Thuringia. It was discovered by chance in 1799 and integrated into the Altenstein park that was being built during this time. It offers a unique exposure of a 258 million year old reef. The cave is also known among speleologists as the first comprehensive anatomical studies of the cave bear were carried out here.

  • Altensteiner Park

The Altenstein castle and landscape gardens are known far beyond the borders of Thuringia. Georg I of Saxony-Meiningen had the complex and a castle built as a summer residence between 1798 and 1803. Geological elements such as conspicuous rock formations and the Altensteiner Cave were included in the park. The ruler wanted to show his interest in science, especially in the modern geology that was just emerging.

  • Outcrop at the ravine near Schmerbach

The rock profile on the hollow path near Schmerbach shows a basal Zechstein outcrop with a very unusual fossil content. The fauna in the copper shale, for example, contains a large number of soil organisms that normally do not exist in this low-oxygen environment. They are evidence of the formation of reefs and thus of an earlier formation of copper slate .

  • Miners' settlement in Catterfeld

In the northern part of Catterfeld there are still four one-story houses of a former miners' settlement. The plots are hardly larger than the house area. The houses date from the time of cobalt mining in the 18th century. At the nearby Ziegelberg, this raw material was mined for the blue paint works.

  • Big island mountain

At 916.5 m above sea level, the Große Inselsberg is only the fourth highest mountain in Thuringia, but it is also the most famous peak. It towers over its foreland by 100 m and is visible from afar. The Inselsberg used to be a special volcanic shape: a so-called dome with very viscous lava that never ran over the edge of the chimney.

  • Mountain lake on the Ebertswiese

The mountain lake on the Ebertswiese is a former quarry, the bottom of which is now filled with water. Between 1900 and 1942, the Hühnberg dolerite was mined here, a high-quality raw material from which crushed stone, paving and stone blocks were extracted. The open pit has been used as a bathing lake for a long time.

  • Chamber rupture

For centuries, the Rätsandstein of the Seeberg represented an important raw material basis for the building activity. The yellow-brown sandstone of the Seeberg is mainly used in representative buildings in Gotha, Eisenach and Erfurt. The quarry is still active today. The Kammerbruch offers the most comprehensive geological profiles of the Upper Keuper and the Lias in the Thuringian Basin.

  • Maternbrunnen near Grabsleben

The Maternbrunnen near Grabsleben is a stratified source that arises when the underground rocks that conduct and retain the groundwater change frequently. The spring was used to supply drinking water to the town of Grabsleben until the 1980s. The Way of St. James also leads past the fountain.

  • Stream shrinkage at the former Pohlmühle

The term stream shrinkage is used to describe the sinking of the apple towns near Schwabhausen . Regularly, but especially in dry seasons, the water withdraws into the subterranean cleft system of the karst and comes back to the surface at another point. This is a natural process.

  • Badlands in the three-of-a-kind area

On the southern slope of the Wachsenburg, Mühlburg and Gleichen Castle, every visitor is struck by the poor vegetation with its strong red-brown to gray-green color: the so-called badlands . Soil can only form poorly here and therefore the area cannot be used for agriculture - hence the name. Mudstone and stone marl banks are exposed here on the surface.

  • Kittelsthaler stalactite cave

The Kittelsthaler stalactite cave is a karst cave that is created by chemical dissolution of limestone (here from Zechstein reefs). The cave is much younger than the surrounding rock, it was only formed when the reef limestone was exposed 1.7 million years ago. The cave was probably discovered in 1888 and has been used as a show cave since 1919.

  • Grove rocks

The Hainfelsen is a natural rock formation on the western steep slope of the Kleine Leina . It consists of Tambach sandstone and the so-called “Finsterberg conglomerate”, which is made up of various pieces of rock (granite, slate, porphyry). The rock has been protected as a natural monument since 1938.

  • Hohenkirchen gravel works

In the Ice Age, the Apfelstädt deposited gravel sands from the Thuringian Forest here. At that time the course of the river changed more often and the apple town did not yet have its current river bed. The gravels consist mainly of volcanic rocks: porphyry and porphyrites. The Hohenkirchen gravel plant is still active.

  • Gerberstein

The Gerberstein was mentioned in a document as early as 933 as "Gervuenstein" and is therefore the earliest summit of the Thuringian Forest to be mentioned by name - although it is only 728 m above sea level. The hardened erosion consists of Ruhla granite. From the Gerberstein, which has been under protection for biological and local history reasons since 1940, you can see as far as the Rhön when the weather is good.

Geographic information center

The first geographic information center of the GeoPark Inselsberg - Drei Gleichen was built in the culture barn in Mühlberg. Here is the permanent exhibition “Thuringia 230 million years ago” by the Trias Verein Thüringen e. V. integrated. The second was opened on the island of the former moated castle in Günthersleben . Together with the local history association, a permanent exhibition was set up that provides information about the regional history, flora and fauna and of course the geology in the Geopark and is intended to serve as a point of contact for all visitors.

Another geographic information center was opened in December 2015 at the Friedrichrodaer Marienglashöhle . It shows the most important rocks and fossils in the Geopark, a geological model and three large dioramas on various wetlands in the earth's history and today.

Geopaths / geo routes

With the geo-routes, the geotopes were grouped into hikes of different sizes and sorted thematically. In some cases, existing trails from the region were also included.

  • Ursaurierpfad "Prof. Wilhelm Pabst ": primeval dinosaur site Bromacker (1 km / 2.7 km)
  • Castle route: Mühlberg-Haarhausen-Arnstadt (9 km, 16 exhibits)
  • Seeberg route: Gotha-Seebergen-Günthersleben (16 km, 11 exhibits)
  • Panoramaweg: Mühlberg-Röhrensee (13 km, 18 exhibits)
  • Wachsenburg route: Haarhausen-Holzhausen-Bittstädt (11 km, 13 exhibits)
  • Apfelstädt-Jacobsweg route (27 km / 35 km)
  • Geology and mining around Friedrichroda (9 km, 17 exhibits)
  • Geology and mining nature trail Trusetal (19 km, 39 exhibits)
  • The nature trail "Around Bad Liebenstein" (12 km, 24 exhibits)

Member communities of the GeoPark

Web links

Commons : Nationaler Geopark Thuringia Inselberg - Drei Gleichen  - Collection of pictures, videos and audio files

Individual evidence

  1. ↑ Opening of a new information center in the GeoPark. In: geopark-thueringen.de. November 30, 2015, accessed October 25, 2018 .