North-east of Ilfeld, the extended hill of the Poppenberg rises up 600 m above sea-level along the southern margin of the Harz, dominating the landscape of the southern Harz rim. We can reach the summit either from Ilfeld (about 4 km), from Neustadt (about 1,5 km), from the train station “Netzkater” (about 3,7 km) or from the parking area designated as “Tisch” (table) at the foot of the northern slope of the Poppenberg (about 1,5 km). The Poppenberg is composed of sediments and volcanic rocks from the Rotliegend formation. Because of the varying degrees of hardness of the rock beds in resisiting the forces of weathering, the hill mounts up over its surroundings with step-like morphologies, a phenomenon particularly obvious in the ascent up its southern slope. At the base, a coal-bed from the lower Rotliegend formation crops out along the northern slope, which prompted mining activities at various sites in the past. On the way to the summit, we traverse various types of rock formations, including sandstone and claystone beds and an almost black, effusive igneous rock called the Ilfeld melaphyr. The hill top is composed of red brown ryolite, the so-called Ilfeld porphyrite. Even today, this nearly 300 m thick lava bed covers an area of about 55 km2. At the uppermost point of the hill, the Poppenberg Tower is located. This steel grid construction from 1894 was entirely rebuilt in 1994. From the tower, which is open to all without cost, we have a scenic view of the entire expanse of the lower Harz up to the Brocken Massif. When the weather conditions are good, the view extends from the basin of Thuringia to the Inselsberg in the Thuringian Forest. From the Bielsteine or from the location of the Weathervane of Ilfeld one also has beautiful views of Ilfeld, Niedersachswerfen and the Kohnstein (Landmark 7 ).

The Weathervane of Ilfeld, about 3 km away from the Poppenberg Tower, was built in 1872 and reconstructed in 1998. There is a distance of only 1,5 km from here to the Gänseschnabelfelsen “Goose Beak Cliff” (Geo-point 6 ).

tarting at the train station “Eisfelder Talmühle” of the Harzer Schmalspurbahnen, we reach the "Kellertalskopf" via a 2,5 km long hiking trail. The "Kellertalskopf" is located in the “Stiftsforst” of Ilfeld, a monastery forest. Here one is presented with a magnificent view over the large modern quarry of the “Hartsteinwerke Unterberg” KEMNA BAU Andreae GmbH & Co. KG. In Devonian times, about 400 million years ago, the central German region was situated near the equator, and was part of an ocean where sediments derived from neighbouring continents were deposited. Today, we find clay and sand in the form of slate, graywacke und quartzite. In calm and shallow seas, corals formed limestones. Volcanic activity produced lava flows along the sea floor, which we now encounter as diabas. At the end of Devonian times, the Variscan orogeny began to manifest itself. The area of the Mid-German Crystalline Rise between the Kyffhäuser Massif and the tectonic structure of Ruhla was lifted up from the sea while, at the same time, the adjacent marine basins subsided. Huge masses of debris were transported into the sea, deposited as what we now, for the most part, encounter as graywacke, a sandstone-like lithology containing considerable amounts of rock fragments and remains of the mineral feldspar. Induced by earthquakes, landslides of unlithified sediment masses - in which lithified, older sediment bodies were also partly incorporated - glided down along the steep slopes of the continents. Those mud flows resulted in the transport and redepositing of entire rock formations for a distance of 25 km from the Mid-German Crystalline Rise to the north-west. As a part of such a gliding mass, the “Südharz Graywacke” formation reached a thickness of up to 400 to 500 m in the northern part of the Nordhausen district. In the past, the “Südharz Graywacke” was excavated in numerous small quarries. Today, it is exploited in the large quarry at the Unterberg and is used in the production of high grade mineral construction material, such as crushed sand, grit and gravel.

www.kemna.de

The only hard coal mine accessible and open to visitors is the Rabenstein coal mine, directly located at the „Netzkater“ train station of the Harzer Schmalspurbahnen Railway. It can be reached by train from the northern as well as from the southern Harz region. The mine can also be reached by car via the federal road B 81. There is adequate space at the mine for parking. Mining of the coal bed at the Rabenstein began in 1737. From its very inception, the exploitation of coal here was confronted with problems. For decades, both a legal dispute between the Ilfeld monastery and the Duke of Stolberg- Wernigerode as well as the inferior quality of the coal hampered the development of any profitable mining enterprise. Mining was stopped, but then reactivated a number of times. Mining periods took place between the years 1737 – 1770, 1831 – 1836 and 1849 – 1880. The mining tunnel system ultimately reached a length of 6,500 m. In contrast to the better known German and European occurrences of hard coal, which are of Late Carboniferous age, the hard coal of the Harz was formed during Permian times. Three hundred million years ago, after the Variscan orogeny, or mountain building processes, the area of the young mountain range was characterized by a warm and dry climate. Weathering processes set in with their destructive impact at the end of the Carboniferous period, immediately after the tectonic uplift of the mountain range from the marine environments. Products of weathering , such as boulders, gravel, grit, sand and clay, were accumulated in the center and at the margins of large mountain basins, which slowly sank deeper and deeper. Because of the predominant red colors of these sediments, the lower part of the Permian period is designated as “Rotliegendes”, which describes the red layered formations. One of these sedimentary troughs, filled with debris from the Variscan orogeny, is the Ilfeld Basin. Here, at the beginning of the Permian period, warm and humid climates generated extensive growth of vegetation. As the plants died off, their remains were soon covered by muddy sediments, and, under the exclusion of air, were slowly altered to coal. On the old stock piles, one can still find, within the mud which has been lithified into claystone, occasional exquisite imprints of plant remains from the Rotliegend period, such as fern leafs and parts of horsetail plants.

The rock gate near Neustadt is situated not far from the garden park east of the spa and can be reached from the parking area at the "Zapfkuhle", a picnic and barbecue site. As in the Ilfeld valley, the spectacular rock formation of the gate developed as a result of the varying levels of resistance of the porphyrite lithologies. Here, like a gateway, the porphyrite formations block a wide valley coming from the Harz, leaving only a narrow passageway free. Via this gate, we are able to enter the coal mining district of Neustadt. Coal mining began here in 1730 with small scale open pit mining. By the middle of the 18th century, the occurrences of coal immediately beneath the surface were depleted and extraction was resumed via deep shaft mining. The shafts and tunnels reached a depth of 80 meters. In the Neustadt district, as in the area of the Rabenstein (compare to Geo-point no. 3 ), hard coal from the coal bearing beds of the Rotliegend age was exploited. This source consisted of three coal beds ranging in thickness from 25 to 70 centimeters. The economic development of coal mining in the Neustadt area was in a state of constant vacillation. The final continuous phase of operation lasted until 1862. Coal mining was finally closed down because of the depletion of resources, drainage costs that were too expensive and a lack of capital. Today, in the area of Vaterstein – Felsentor we can find the following remains of coal mining from the past:
• old open pits along the south-eastern slope of the Vaterstein which can be recognized in
depressions 3,5 m deep
• old adit entrances which are only visible as narrow passes of the former access roads.
• former shafts, recognizable as a “pinge”, or a hole of about 5 m depth, surrounded by a sickle-shaped stockpile.
• the “Stollenborn” (shaft-well) located close to the "Zapfkuhle" picnic and barbecue area, an element of the former water drainige system of the Vaterstein coal maining district.

Neustadt-Information
Tel.: (036331) 46277

www.neustadt-harz.de

Starting from Ilfeld, a 3,5 km long sign-posted hiking trail leads to the “Braunsteinhaus” in the middle of the deciduous forests of the southern Harz. The "Braunsteinhaus" can also be reached on a reinforced field road which branches off from the country road between Ilfeld and Appenrode.The “Braunsteinhaus” is the former colliery’s house of the manganese ore mining district. Here, manganese ore mining was probably already taking place in the middle ages and began to be carried out professionally with the advent of the 18th century. “Braunstein” is the old mining term for unrefined black-brownish manganese ores. Already in medieval times manganese was a raw material in demand. The “Venetian Tales” recounted throughout the Harz can be traced back to prospectors from Venice who carried out their search for “Braunstein” of high quality here. Since the early middle ages, Venice had been the center of European glass manufacturing. One of the well guarded secrets in Venice was a process of producing colorless glassware which required the addition of manganese oxide. Along with manganese ores, iron ore was excavated in the “Gräflich Stolberg Hohnsteinschen Forst” (the forest of the Duke of Stolberg-Hohnstein). Manganese ore was mined here until 1890, when the operations were terminated because of depletion of the deposit. A second mining period followed, beginning in 1916. Manganese mining in the area of Ilfeld was finally closed down definitively in 1922. From the “Braunsteinhaus”, we begin our circular hiking tour along the 2 km long educational trail which starts in the former manganese mining district. Twelve stations exhibit various relics of former mining processes such as stockpiles, open mining pits with steep slopes, shaft remains and collapsed adit entrances. These artifacts have their origin for the most part in the last period of operation during World War I. It is recommended that visitors take along the accompanying informational booklet which can be purchased in the tourist information bureau in Ilfeld.

The reddish-brown Ilfeld porphyrite is a rock type with various degrees of hardness. The material is, in part, very crumbly and weathers relatively quickly und deeply down to a residue. In close proximity to such occurrences, the same lithologies can be very resistent against the forces of weathering and occasionally form bizarre cliffs. Such cliffs are exposed in numerous valleys in the southern Harz. Because of their strange morphologies, these forms have inspired people to find their own names for the most spectacular rock formations, names quite often derived from legends. The most remarkable cliffs of the Ilfeld valley are “Gänseschnabel” (the goose beak), “Mönch” (the monk) and “Nadelöhr” (the needle’s eye). The name “Needle’s Eye” was given because the cliff is characterized by a narrow fissure. According to the legend, all cart-drivers who wanted to enter the Harz had to get past this cliff. Newcomers were required to creep through this fissure, accompanied by the applause of their comrades. In case they got stuck, the others “assisted” with their whips. There was, of course, also the possibility of freeing oneself from these exertions by paying a thaler as ransom fee. The rock cliffs can be visited at the northern outskirts of Ilfeld on a comfortable hiking trail along the river Bere. Following this trail in the direction to Netzkater, we encounter a narrowed passageway through the valley where the river Bere had to find its way through an accumulation of giant rock debris. This romantic part of the valley, called “the little Bodetal”, is the result of a prehistoric rockfall in which masses of porphyrite blocked the valley and dammed up the river Bere.

The “Lange Wand”, located south of Ilfeld, can be reached by foot or by car, driving along a side street through the village from the rail-way stop Ilfeld “Schreiberwiese” of the Harzer Schmalspurbahnen. This stop is located adjacent to the federal road B 4. The “Lange Wand”, a steep slope along the left bank of the river Bere, is a classical geological exposure. It offers an impressive demonstration of various evolutionary cycles in the history of the earth. Magmatic rocks from the lower Rotliegend formation repesenting a former terrestrial surface are overlaid in a sharp demarkation by marine sediments from the Zechstein period. The copper shale, which is exposed in this profile, was the object of mining activities. When the Harz was lifted up in Rotliegend times about 300 million years ago, the region was covered by 300 m thick lavabeds as a result of intense volcanic activity. The surface of these lavabeds still extends over an expanse of 55 km2 . At the end of these turbulent times, permanent weathering completely levelled the mountain range. This flat land surface was once again flooded about 255 million years ago. This invasion marks the beginning of the Zechstein period, a geological period of special significance for our region. On the shores of the Zechstein sea, sand and gravel were deposited, as always along marine shore lines. The water steadily penetrated further inland and, in regard to our location, progressively became deeper and deeper. On the sea floor, black shale rather than sand was deposited. The mud contained compounds of copper, silver and other valuable metals. Fish living in the sea sank to the bottom after their death and were deposited in the mud. The marine basin was transformed into a shallow sea flooded with light, similar to today’s tropical coastal regions. Calcareous sediments developed from the bodies of organisms living in warm waters. Further development of the Zechstein marine basin resulted in an enormous formation of gypsum and anhydrite deposits as well as halite and potassium salts in the center of the Thuringian basin. At the “Lange Wand” outcrop near Ilfeld, we are positioned exactly at the boundary between the levelled lava flows (Ilfeld porphyrite) of the Rotliegend period and the Zechstein deposits. We recognize the porphyrite, which is bleached by the sea waters, and above it, the beach sediments of the Zechstein period. These are composed of the “Zechstein conglomerate”, a coarse grained sandstone-like lithified beach deposit, the metal-bearing mud which is now a thin layered shale designated as “Kupferschiefer” followed by a bed of limestone, which was once calcareous mud and now constitutes the “Zechstein-Kalk”.

The mine to be visited, “Lange Wand”, is located about 100 m north east of the classical geological exposure, both on the left bank of the river Bere. At the Geopoint “Lange Wand” we first looked through a window of the earth’s history and gained insight into Permian times, and here, at the mine, we can now observe aspects of the interior of the earth as it was seen by the miners. Mining activities here probably go back to the 16th century. Initially, cobalt ore and baryte (“heavy spar”) were mined in several tunnels, later to be followed by the excavation of copper shale. At the end of 1860, mining activities were finally terminated. There had been no real economic success during any of the operational periods. Today, however, thanks to this activity in the past, we are able to observe, along with copper ore in the “Kupferschieferflöz”, well developed occurrences of cobalt ore within the so-called “Erz-Rücken” (ore ridge). We also can view different mining technologies side by side: the mining of ore dykes and the mining of ore beds.

Opening times with tours: March to October, Wednesdays
2:00 and 3:00 p.m. or by request +49(0)36331 32033

Above the spa of Neustadt, the ruins of the former castle of Hohnstein are to be found. Built at the beginning of the 12th century, the castle was devastated during the 30 Years War. Even today, however, it remains one of the largest and most impressive historical fortresses in the Harz region. After extensive restauration and safety measures carried out by the Nordhausen County administration, the ruins can be visited and offer an attractive and popular destination for outings. Castle Hohnstein is located on the top of a rocky cliff in the center of the area of the Ilfeld ryolite occurrence (“porphyrite”), hence a dark red-brown porphyrite as the preferred material for construction. The natural subsurface – the cliff itself designated as the “grown rock” - and the man-made structure consist almost entirely of the same material. The walls and building remains give the appearance of being a natural continuation of the underlying rock formations. It is apparent that stones used for the construction of the castle were taken from its immediate surroundings and probably originated in part from the actual site of the castle itself. But today it is impossible to localize any specific quarry from which the rocks used to construct the building were excavated. In addition to the porphyrite, various other rock types were used as construction material, in particular the local gypsum. It is of significance in its use as the mortar which can be found as white joint fillings. This contrast of white joints to the dark brown porphyrite lends an interesting aspect to the castle. Calcined gypsum, or plaster, was also widely used for the production of plaster stone flooring. Remains of these floors are to be found at numerous points in the castle. Occasionally, gypsum as alabaster also served as workstone for the production of delicate structures. In addition to these main construction materials, almost all rock types of the surrounding area were appropriated for the construction and preservation of the castle. Rough slate plates from the Harz were used for roofing, sandstones from the Kelbra region for the construction of wall arches, limestones from the Thuringian basin for cornices and local fluvial gravel for the paving of stables and the kitchen. On a walk across the castle site, not only the old walls are of interest. From the castle yard of the ruins, or even better from the castle keep, we are offered a panoramic view over large portions of the old dutchy. On a clear day, the hill sites of the Kyffhäuser, the Hainleite, the Eichsfeld and the Ravensberg are visible.

This former municipal quarry is located in the north eastern edge of the Osterode district of the municipality of Neustadt/ Harz and belongs to the geological structure designated as the “Ilfeld Basin”. The basin represents the largest occurrence of the Rotliegend formation in the Harz and covers an area of about 120 km2. In the area of Ilfeld – Neustadt, it is characterized by thick ryolitic volcanic sequences. This volcanic complex, called the “Ilfeld Porphyrit” in earlier literature, extends over an area of 50 km2. There are, however, very few volcanic vents and centres of lava production normally associated with such a complex to be found here. The exposure at the Bornberg represents a center of lava production which developed as a cupola of stagnation with ideal structural configuration.

Here, the ryolitic lava penetrated previously deposited but not yet lithified ash flow sediments, and formed, in the course of several phases, a dome-like structure. Because of its specific hardness, the volcanic rock designated as ryolite (“Ilfeld Porphyrit”) was excavated at this site. As a result, the exposed inner structure of the cupola of stagnation was gradually rendered visible, yielding vivid impressions of the flow activity in the course of the Rotliegend volcanism.

Hotel "Am Kloster" Ilfeld/Südharz

Tel.: +49 (36331) 366

Hotel “Hufhaus“ Harzhöhe, Ilfeld
www.hotelhufhaus.de
Tel.: +49 (36331) 48125

The map will help planning your personal geo-route around the Poppenberg Tower. Professional guided tours can be organized (contact: www.ilfeld.de). The “Regionalverband Harz e.V.” wishes you a pleasant visit and interesting insights into the geology and history of the portion of the Geopark Harz which is presented here.

Authors: Dipl.-Geol. Helmut Garleb, Dr. Klaus George
Photos: Dipl.-Geol. Helmut Garleb, Dr. Klaus George, Rabensteiner Stollen e. V.
Editors: Dr. Klaus George, Christiane Linke
Translators: Dr. Torsten Steiger, Dr. Harriett Watts