The Kohnstein Mt. near Niedersachswerfen remarkedly dominates the landscape. As the mountain’s steep natural steps have long made an impression on people, it has been documented in numerous historic portrayals. Today the scene is influenced by anhydrite surface mining which has removed a large portion of the mountain massif. The Kohnstein massif consists of massive anhydrite of the Werra sequence, which has a thickness of approximately 400 m, with a gypsum crust, and is, in its highest sections, enclosed by the remnants of the main dolomites of the Staßfurt sequence. Many types of karst phenomena have developed in the gypsum formations of the Werra anhydrite. As early as 1917 the BASF Company had begun underground extraction of anhydrite: the history of the creation of an intricate system of manmade caves began. Up until 1935 about 35 million tonnes of anhydrite had been extracted (in part in surface mining) and delivered to the Leunawerke Merseburg for chemical processing.

The Karst Trail, which also passes through the Kohnstein area, is both a landscape-oriented nature trail and an interdisciplinary thematic information trail with geo- scientific emphasis. It stretches for about 200 km from Förste in the west (Landmark 11) to Pölsfeld in the east (Landmark 12) with around 200 information boards along the route. The trail connects the southern Harz karst landscape, crossing the borders of three German states: Lower Saxony, Thuringia and Saxony-Anhalt. From the west it reaches the district of Nordhausen in two branches which join to form a single trail near Gudersleben. Many of the geo points described in this flyer lie along the Karst Trail. Trail markers with a red stripe on a white background identify the route of the Karst Trail in the central and eastern sections.

Tourism – Information Centre Nordhausen
Tel. +49(0)3631 902154
www.nordhausen-tourist.de

Characteristic of this Landmark is the karst. Directly outside the community of Buchholz, in the direction of Stempeda, is a geological fault. Water seeping from the fault has partially dissolved the highly soluble gypsum of the Zechstein. First karst caves were formed, which later collapsed. Evidence of this process is the nearly 30 m deep Buchholz sinkhole (N51°32.412´; E010°52.129´). An information board illustrates the particular local situation. The term “karst” has its origins in the Croatian landscape and describes a limestone region marked by sinks and interspersed with abrupt ridges, irregular protuberant rocks, caverns and underground streams. Where there is restricted precipitation and an extensive underground karst network to drain surface water, river and stream beds can run dry for a period of time during the year. The cause of karst is the high solubility of the limestone, dolomite and gypsum rocks, as well as rock salt and potassium salts. In most karst regions it is the dissolution of limestone that leads to karstification, but in the southern Harz it is the gypsum in particular that is responsible (alongside dissolution of the dolomite). Gypsum is 100 times more soluble than limestone: 2 grams of gypsum dissolve in one litre of water! When the less soluble anhydrite is exposed to the influence of water it is converted to gypsum. If sufficient water is available, fractures and cavities develop from fissures, cracks, and stratification in the rock. These can eventually lead to a portion of the surface water disappearing underground through streamsinks or sinkholes, where it becomes part of the groundwater system. The groundwater moves more readily through cavities formed or enlarged by the karstification process and can resurface in more or less distinct springs. Water tracing experiments have in some cases established a direct connection between karst springs and surface water which has disappeared underground. Water flowing into the Buchholz sinkhole was also dyed, but the location of the water discharge could not be determined. It is speculated that the water flows in a southerly direction into a large underground karst stream in the region of the Goldenen Aue. Karstification has led not only to the formation of sinkholes but also to leaching depressions and caves as well as to the development of the morphologically very complex and broken gypsum karst landscape.

The Salza Spring, directly south of the Kohnstein Mt., lies on the Karst Trail and represents a key hydrogeological feature of the underground water of the southern Harz Zechstein Belt. Having an average discharge of about 400 L/s, it is one of Germany’s most important karst springs and is considered to be the most powerful spring in Thuringia. Direct connections between the Salza Spring and sunken surface water, in particular of the Wieda, have frequently been and are still being assumed but no concrete proof has yet been provided. The last comprehensive research work concerning the karst hydrogeology of the southern Harz Zechstein Belt was carried out by HAASE (1936). HAASE comes to the conclusion, in concordance with modern theory, that the Salza Spring is not connected to a specific karst channel but rather that it drains an underground catchment area lying in the region of Zechstein outcrop, in which groundwater regeneration from precipitation as well as surface water drainage contribute to the groundwater supply. As the spring water has a nearly constant temperature of 9.5°C, the Salza Soring does not freeze even in heavy frost and for this reason was for some time of great importance to twelve mills located below it.

From the Salza Spring we follow the Karst Trail westwards along the knolls of the Hörniger Kuppen. This charming landscape on the west edge of the Kohn stein massif is part of the Sattelkopf Natur schutz gebiet, a nature protection area. At the fork of the Karst Trail near Gudersleben we walk in the direction of Appenrode and arrive at the Kelle, a gypsum cave (N51°34.486´; E010°43.045´). In 1589 the first cartographic description of the cave was recorded. The cave was originally comprised of a voluminous 85 m long cavern with an underground lake and a small opening in the ceiling through which daylight fell. An excellent example of the decomposition of a karst cave formed by gypsum leaching is found in the Kelle: thanks to early descriptions and its later wide-spread fame it is well documented. Before the Reformation the Kelle served as a place of pilgrimage. A procession of pilgrims would walk to the Kelle, a priest would dip a cross in the cave lake and call to the believers, “Come and look into the Kelle and so you shall not go to hell!” A legend repeated around Ellrich has it that the cave lake with the unusual name (a “Kelle” is a ladle) originated as follows: once upon a time there was a poor orphan girl who had pledged her heart to her finance, but he was unfaithful. She saw him kissing and hugging another young woman. She fled into the woods crying bitterly, lamenting her fate and wishing she were dead. Since in springtime all wishes come true, a man of great stature suddenly appeared out of nowhere. He carried the tools of a mason. Without speaking he looked down at the girl with great sympathy. Then he threw his mason’s ladle down onto the ground with such force that the earth opened up and swept the girl into its depths. The opening immediately filled up with water. Still to this day the face of a melancholic girl is said to appear on the surface of the water from time to time. Either the day on which her wish comes true has not yet come, or she no longer has the wish and prefers to remain forever in the depths. Since about 1770 rapid disintegration of the cave has taken place so that today it--quite impressively--presents a complete ensemble of karst phenomena: a collapsed sink divided in two by a natural bridge, a half-open grotto adjacent to it and the cave lake.

Tourist Office Ellrich
+49(0)36332 260
www.ellrich.info

Lying directly adjacent the street connecting Krimderode and Rüdigsdorf, both part of Nordhausen, at the edge of a widereaching doline (a closed depression draining underground in karst areas: here, it forms a broad valley feature) is a former rock quarry (N51°32.076´; E010°47.775´). The quarry, classified as a nature monument area, is part of the Rüdigsdorfer Schweiz Landschafts schutzgebiet, a landscape conservation area, which is well know for, among other things, its pronounced karst manifestations and the plant and animal communities specific to it. In the quarry, gypsified anhydrite of the Werra sequence was quarried. The well preserved quarry walls reveal the internal structure of the strata. The gypsum is finely stratified. Easily recognisable is the interbedding of thin beds of pure white gypsum-- the alabaster--and grey gypsum discoloured by clay and carbonate impurities. Layers of particularly pure gypsum with a thickness of 20 to 40 cm, the so-called alabaster nodules, are intercalated in this interbedding. Alabaster is an easily workable material from which statues, vases and similar artefacts were formerly produced.

Starting from the Waldhotel Kalkhütte we can walk along the Grenzweg border trail through the extensive copper beech forests of the Alter Stolberg Naturschutzgebiet, a nature conservation area. The Alte Stolberg region is characterised by sinkholes and other distinctive karst manifestations. Not far from the Waldhotel Kalkhütte an information board provides preliminary explanations of the formations along the Karstwanderweg (Karst Trail). The trail follows along the former border between the Electorate of Saxony and the Kingdom of Hanover up to Border Stone No. 100 (N51°31.335´; E010°53.825´). Border disputes between the principalities of Saxony and Hanover came to an end with an agreement signed in Nordhausen on August 30, 1735. It prescribed that the existing wood border posts be replaced with 252 border stones. On the Hanover side a horse, and on the Saxony side the pacing lion were to be chiselled into the stone. The lion was the heraldic animal of the County-State of Thuringia which was assimilated into the Electorate of Saxony- Wittenberg in 1423. Still today the German states of Lower Saxony and Thuringia bear the horse and the lion, respectively, in their coats of arms.

The town of Nordhausen was first mentioned in 927 in a deed of donation from HEINRICH I to his wife MATHILDE. In the 13th century the construction of a stone fortification was begun. Recurring feuds with the Earls von Hohnstein, Stolberg and Schwarzburg made an extension of the town’s fortifications necessary. In the 14th and 15th centuries the town wall was enlarged and further fortified with additional defence towers. Four main gates gave access to the town core: Töpfertor, Rautentor, Neuewegstor and Barfüßertor. The surrounding villages were obligated to supply the stones for constructing the town fortifications. The most frequently used building stone was dolomite, which was quarried on the Kohnstein . An air attack shortly before the end of the Second World War destroyed 70% of the town. This is one reason that only 1,600 m of the old town wall remains to be seen today. Our tour of the town begins with a walk through the Altstadt (Old Town). A prominent building is the Dom zum Heiligen Kreuz (Holy Cross Cathedral) from around 1130. The Roland figure, first mentioned in 1411, was formerly a symbol of a town’s independence and its jurisdictional and market rights. Our tour closes with a visit to a large piece of land which was first planned and landscaped in connection with the Landesgartenschau (State Garden Show) in 2004. Here we find especially impressive remnants of the once sturdy surrounding wall with its defence towers. Testifying to the impact of the shock wave of detonating bombs on April 4, 1945 is a displaced block from the stone obelisk erected in 1880 in commemoration of the fallen sons of the town in the wars of the 19th century (N51°30.06´; E010°47.92´).

City-Information Nordhausen
Tel. +49(0)3631 696797
www.nordhausen.de

Also worth seeing is the town wall in Ellrich. The first documented mention dates from 1315 and still today connected segments can be seen. A shorter and less strenuous access to a new street built in 1912 was given an imposing archway (N51°35.147´; E010°39.984´). The town wall of Ellrich was also constructed of indigenous stone. Also recommended is a visit to the oldest ensemble of wood frame buildings in Ellrich, the Hospital (almshouse), which was founded in the 12th century by the Walkenried Monastery (Landmark 16).

Approximately one km southwest of Steigerthal a group of stones stands on the Haard (N51°31.061´; E010°51.483´). According to legend the porphyry cross and two companion stones were erected as a reminder of a bell founder from Stolberg having murdered his journeyman for casting a bell more successfully than his master. The actual age of the stone group is unknown. An atonement cross is supposed to remind those passing by to offer a prayer for the soul of the murdered person.

In regard to the Sühnekreuz (atonement cross) on the Hohe Straße (N51°36.332´; E010°40.971´) near Sülzhayn, the saying has it that it was erected in memory of a monk who was murdered here. The man of God is said to have been a victim of robbery in 1774 as he was making his way home from selling products of the Walkenried monastery. Even 200 years later there was a time in which people who varied from the “right way” had to fear for their lives in this region: Sülzhayn was situated immediately on the inner-German border. Earlier known as the “Davos of the North”, it suffered greatly, but it budded into bloom again! Symbolic for this is the yearly Rhododendron Festival. Previously well known in all of Germany as a curative climatic health resort, the place once again has something to offer, even for those interested in geology. Formerly there was mining in the surroundings. Bituminous coal, in particular, was excavated in the Steierberg district (the Anna Gallery). The area is interesting for fossil and mineral collectors. The exhibit “Wald, Feld, Wiesen und Geologie” (“Woods, Land, Meadows and Geology”), located in the apartment building named The Ark, Dr. Kremser Straße 42, provides an impression of the area. The exhibit can be viewed daily from 4:00 p.m. on or earlier by prearrangement ( +49(0)36332-72725). Quite nearby a sign points the way to the Sühnenkreuz, an atonement cross hewn out of limestone.

In the Golden Aue area, which is just within the rim area of the Thuringian Basin, an area of subsidence parallel to the Harz rim was formed by intensive saline leaching beginning in the Tertiary as a result of the Harz upheaval. As early as the Pleistocene, about 400,000 years ago, the Zorge River flowed through this area of subsidence, depositing material eroded from the Harz, especially in the form of gravel and sand. The rate of ground settling and the rate of alluvial filling of the area of subsidence in the Golden Aue were more or less equal for a long period of time so that, today, a layer of gravel, sand and other loose aggregates, up to 80 metres thick, lies there. These provide, on the basis of their scale and quality, an important economic resource in the southern Harz and the materials are extracted in a number of surface mines. The aggregate sequence of the Golden Aue is saturated with ground water, which is released during gravel extraction. The bodies of water thus formed have in the meantime become the characteristic feature of the landscape. Pleasant areas for relaxing (N51°28.877´; E01049.956´) can be reached from the B 80 in Bielen along the “Marktstraße” street, past the sports field and, after crossing the Zorge River, turning to the right into the “An den Kiesteichen” street.

The Geoparkinfostelle Werna is a geopark information exhibit which has been installed in the refurbished supervisor’s house on the grounds of the former estate of the Barons VON SPIEGEL. A particular attraction of the exhibit is a model explaining the function of karst. Here the flow of surface water and groundwater in the karst landscape is demonstrated. In the building exhibits presenting homeland history, historic border stones and nature in the region can be viewed. In the adjacent park there is much for all visitors to discover.

Opening hours:
Mo.– Fr. 10:00 a.m.– 4:00 p.m. and on request

Waldhotel Kalkhütte
Urbach - Alter Stolberg
kalkhuette@t-online.de
Tel. +49(0)36333 60870

Waldhotel Sülzhayn
Ellrich OT Sülzhayn
www.waldhotel-suelzhayn.de
Tel. +49(0)36332 2860

The plan can assist you in planning your own personal georoute round about the Kohnstein. Expert guided tours in German as well as English can be arranged (contact: Förderverein Deutsches Gipsmuseum und Karstwanderweg e.V., www.karstwanderweg.de, wanderungen@karstwanderweg.de). The Regionalverband Harz wishes you pleasant recreation and interesting glimpses into the geology and history of the parts of the Geopark Harz presented here!

Text: Dipl.-Geol. H. Garleb, Dr. K. George, Ch. Linke
Photos: Garleb, George, Meurer
Editing: Dr. K. George, Ch. Linke
Translation: Holly Pankow, Dr. Neal Chapman