The westerly North Harz Border is quite rightly known as the “Classic Geological Square Mile” because here a nearly complete sequence from the Palaeozoic up to the most recent sedimentations are revealed in close proximity. There is an almost entirely unbroken chain of evidence of nearly 400 million years of earth’s history - like nearly nowhere else in Middle Europe! The North Harz Border bears the imprint of a large tectonic fault line on the middle of which Goslar, too, lies. Through the reverse fault of the Harz over its foreland at the Harznordrand Thrust, the strata were shoved up vertically from their horizontal position for more than 4,000 m. Therefore along the Harz Border the lithologic sequence from the Mesozoic is accessible on the earth’s surface. So here rocks from Buntsandstein, Muschelkalk, Keuper, Jurassic as well as Upper and Lower Cretaceous occur; east of Bad Harzburg and west of Hahausen, Zechstein also shows outcrops. Most of the strata are rich in fossils and are or were exposed in numerous quarries, sand or clay pits. Many geological collections have specimens. Particularly worthy of mention are the collection in the Goslar Museum, which provides an excellent overall view of the geologic development of the North Harz, and the mineral collection in the World Cultural Heritage Rammelsberg with numerous specimens from the deposits of the Rammelsberg. Between Goslar and Bad Harzburg Devonian rocks butt the Mesozoic rocks of the Harz Border from the south. They form the broad structure of the Upper Harz Devonian Saddle, in the core of which Lower Devonian sandstones and quartzites occur (Kahleberg Sandstone). From the west the Goslar Trough joins in; the 1,000 m thick Middle Devonian shales with diabases bear witness of submarine volcanic activity. Between the saddle and the trough, fissures broke open, through which metallic solutions rose. They formed ore sludges on the ocean floor, which later solidified into the ores of the Rammelsberg. The residual pollution of land and ground water and other environmental problems resulting from mining and the concurrent smelting, as well as the unique heavy metal vegetation and numerous reclamation attempts, are displayed in an exemplary manner - one could therefore also speak of the “Classic Square Mile of Environmental Geology”.

In contrast to the Upper Harz ore deposits, the Rammelsberg ore was formed on the ocean-floor together with the surrounding sediments. The orebodies lie overturned, that is to say “upside down” - a result of the folding of the Harz Mountains. The ores are rich in lead, zinc and copper as well as other elements, among which are cadmium, gold and silver. For the mine owners of the past, the foremost interest was obtaining copper and silver, and later lead; modern mining concentrated on obtaining zinc and barite. The Old Orebody was probably discovered as early as the Bronze Age. Later- in the middle ages and early modern times – it provided the wealth of the German kings, the Dukes of Brunswick and the City of Goslar. During the high middle ages the major emphasis was on argentine copper ore - so abundant that the Ottonian and Salian emperors built the largest of all their palatinates at the foot of the Rammelsberg. Commerce in metals secured the merchants of Goslar influence in the Hanseatic League. During the second period of prosperity in the Rammelsberg in the 16th century, however, the rights to the mines were taken by the Dukes of Brunswick - to the detriment of the Goslar mine owners, but not to the detriment of mining. A final period of prosperity occurred in Rammelsberg mining in the 20th century, after optimal separation of the finely intergrown ore had been achieved. In 1988 the deposit was exhausted; mining and ore dressing operations were shut down. The Rammelsberg was the only ore mine works in the world which had been in continual operation for over 1000 years. In 1992, together with the Old Town of Goslar, it was entered on the UNESCO World Cultural Heritage List. When visiting the WELTKULTURERBE RAMMELSBERG one encounters important mining monuments everywhere: mine dumps from the 10th century, the Rathstiefste Gallery (12th c.), the Feuergezäher Vault (the oldest masonry-constructed underground mine room in Europe), the Maltermeister Tower (the oldest above ground structure of German mining), the Roeder Gallery (19th c.) with its water wheels, and many others. In four museum buildings permanent as well as changing exhibits covering the life and work of man, modern art - which open baffling approaches to the local work culture - as well as geology and mineralogy are presented.

Our Goslar visit begins at the Kaiserpfalz car park - from here there is a good view of the mighty Romanesque imperial palace. For centuries Goslar was the favourite court and residence of the travelling monarchs. In 1009 the first imperial diet in Goslar took place; the town remained an important centre of power of the German kings and emperors until 1253. At the same time a centre of Christian faith, the “Rome of the North”, arose here: 47 churches, chapels and monasteries delineated the town’s silhouette. Goslar’s narrow Old Town streets are a particular delight, where every house has its own history. The core of the Old Town was laid out in a compact square kilometre. In the midst of it, in a building typical of Goslar - a two-storied late Gothic structure - the Goslar Museum’s collections covering medieval and more recent town history, art and culture, geology and mineralogy of the Harz are presented. In an exhibit newly arranged in 2006/2007 presenting the “classic geological square mile” an information center of the UNESCO Geopark Harz - Braunschweiger Land - Ostfalen is integrated. The reconstruction of a 1000 year old Harz smelting oven imparts information about historic smelting techniques. With these exponents the museum plays an important role as an information station of the Geopark Harz. Along with the neighbouring leather tanning mill it is to become part of further development of the “Museumsufer” in the next years.

Öffnungszeiten Goslarer Museum:

April - Oktober 10.00 - 17.00 Uhr
November - März 10.00 - 16.00 Uhr
(jeweils außer montags)

The 20 metre high rock rib of the Klusfelsen is today hidden behind the home for the elderly at Petersberg 4, east of the Schützenplatz and near the Breites Tor (Broad Gate). It can be reached via the Osterfeld and Petersberg streets. We follow the signs for “Kluskapelle”. The Klusfelsen looks brown due to weathering – but it consists of coarse, porous, yellow Hils Sandstone which was formed in a shallow sea near the coastline in the Lower Cretaceous about 110 million years ago and can reach thicknesses of nearly 100 m. The southerly coastline was only a few kilometres south of where the Klusfelsen stands today in the North Harz Region. The Hils Sandstone is representative of a distinctive transgression of the Niedersachsen Basin. From the sediment structures, for example the cross bedding, it can be assumed that the prevailing ocean current flowed parallel to the coastline from northwest to southeast. The Hils Sandstone was formerly an important quarry stone, quarried mostly in the area of Langelsheim and Lutter am Barenberge to provide building stones for sacred architecture and for modelling of fine architectural elements. The pores of this sandstone are often incompletely filled with quartz cement, thus the stone tends to disintegrate which can lead to structural damage. The nearby classical geosites, the Ratssandgrube and the Osterfeld Brickyard, have unfortunately been demolished to a great extent. The outcrop line Petersberg (Upper Cretaceous) – Neue Ziegelei Osterfeld (Keuper – Buntsandstein) was a unique supraregional geoprofile.

From the Klusfelsen we drive toward Oker and soon see the broad Sudmerberg Mountain with its transmission tower. We turn off to the left in the suburb of Sudmerberg, drive to a car park near the Schützenhaus building and climb the forest path to the top of the mountain, consisting of Upper Middle Santonian (Upper Cretaceous) sandstones. The discordances tell the geologist that the last important movements on the Harznordrand Thrust took place here during the transition from Middle to Upper Santonian. The Santonian beds were built up of alternating stratifications of hard calcareous sandstone and softer clay. The yellow sandstone of the Sudmerberg in particular was quarried for use in construction of many buildings in the Goslar region - like the observation tower, from which, especially in the morning hours, one can enjoy a lovely view over Goslar with the sun on one’s back. Looking toward the Harz the settling basins of the former Lean Ore Dressing Works of the Rammelsberg Mine can be seen. We will stop there as we drive toward the east, passing under the railway bridge in Oker and turning right in the Stadtstieg and then going from the tennis courts up to the Bollrich airfield. Even after the closing of the ore dressing facilities the settling ponds have a function: In them the sedimentation of solid materials remaining after water treatment of the pit water from the former ore mines takes place. Depending on the amount of rainfall, up to 90,000 cubic metres of contaminated pit water per year is treated to avoid further pollution of the centurylong non-ferrous metal carrying Abzucht and Oker rivers. In the smelter community of Oker, ores from the Rammelsberg have been smelted since the middle ages . The non-ferrous metal smelting works in Oker-Harlingerode goes back to the Frau Marien Saiger Metallurgic Plant, founded in 1527. Today primary ores are no longer smelted here - the recycling plants treat materials from all over Europe. Looking over the industrial landscape the white wall of a gigantic geological outcrop attracts our interest: the Langenberg..

At the centre of Oker we turn to the left toward Bad Harzburg. The straight road takes us to the granite region of the Oker valley. Running parallel to the Harzburger Straße is the Harznordrand Thrust, apparent in the steeply uplifted Adenberg – its rocks dating from the Lower Devonian. After several hundred metres we turn left in the direction of Harlingerode and reach the entry drive of the Kalkwerk Oker of the Rohstoffbetriebe Oker GmbH, at the west end of the Langenberg. The gigantic farstretching quarry faces of this quarry expose in the south flank of the Langenberg, steeply over-tilted and dipping to the south, partly dolomitic limestones and marl limestones of the Upper Jurassic. The large Langenberg outcrop area provides a unique view of the strata sequence of the sediments tilted up along the Harznordrand Thrust - it is a dominant landscape element. Especially the limestone is particularly rich in fossils. In recent years saurian bones have been discovered; this gave impetus to the planning of a Jura Park. To visit the quarry it is mandatory to announce your presence and obtain permission from the plant management to enter the site. A stop at the factory fence of the smelting works west of the county road makes it possible to study a well developed and most varied example of Harz heavy metal vegetation with Armeria halleri on heavy metal contaminated ground. The North Harz is a European major frequency area of plant families specially adapted to living on metallic soils - an intriguing environmental-geologic chapter of the Rammelsberg landmark.

www.okerkalk.de

Returning to the Harzburger Straße we continue in the direction of Bad Harzburg, turning off to the right at the Silberbornbad (car park). We walk across the grounds of the horse racing track and the manmade landscape of the stud farm pastures (worthy of protection) which stretch out over the Jurassic and Triassic strata hidden underground. We can see large quartzite blocks lying alongside the road (bicycle path R1). At the edge of the Harz we continue on foot in the same direction for another 600 metres into the Gläsekental Valley. There on the right-hand side of the path we reach a small quarry in which a thick vein of quartz has been exposed: the Elfenstein Vein. It continues easterly upwards along the slope of the Elfenstein, where weathering has formed it into cliffs. This quartz vein was inclined in the wake of the Oker granite, therefore it must be of Late Upper Carboniferous origin. This makes its course even more interesting, as it runs parallel to the Harznordrand Thrust for approximately three kilometres, thereby indicating that this tectonic drift already existed in the late Variscan Era. So the Harznordrand Thrust occurs on a very old structure.

We drive back along the main road, turn off to the right and follow alongside the horse racing track until we arrive at Bündheim, a suburb of Bad Harzburg. We follow along the street further into town and then, in the long left curve, we turn right into the Silberbornstraße. At the end of the street we come to the game enclosure which is on the grounds of the former Friederike Iron Ore Mine. The street name “Grubenweg” (Mine Road) and a directional sign are a reminder of the mining history. Imbedded in the Lower Jurassic (Lias) clays are four ore deposits with a combined thickness of 20 metres. These ores are the product of weathering of dry land nearby (today the Harz Mts.) which even in the Jurassic period lay above sea level. Ore precipitated in the coastal shore area. The ore deposits Peine-Salzgitter were also similarly formed, but originated in the Cretaceous period. The Friederike Mine was famous for its large ammonites; well preserved specimens can be found in the collection of the Goslar Museum, as well as others. The old colliery spoils have been levelled or are inside the game enclosure. There is also little left of the mine structures; only the linear subsidence areas with obvious depressions above the mining cavities are easily detectable.

Bad Harzburg was founded in 1894 when the village of Neustadt became a township, taking its name from the nearby Harzburg Fortress, which was built around 1065 under HEINRICH IV as one of the first Harz imperial fortresses. With its favourable location on the steep Burgberg Mountain it became one of the most important fortresses of its time, playing a key role in the Saxon Revolts and being plundered and destroyed in 1074. After reconstruction under OTTO IV it regained fame: the imperial insignia of the Holy Roman Empire were kept here. The death of OTTO IV in the fortress ended its role of importance. Still existing on the Großer Burgberg is the 57-metre deep fortress well. From the Canossa Column on the Burgberg there is a tremendous view out over the Northern Harz Border and the area of our previous excursion route as well as the Harz Foreland lying further to the north. Out of this the individual hillside ranges, formed by salt tectonics, such as the Harly Anticline (salt saddle) near Vienenburg with its former potassium mine, rise. Bad Harzburg is known today for its saltwater baths, fed by the springs originating in the Harznordrand Thrust. A total of six curative and mineral water springs gush from the earth here. As early as 1569 a saline which continued operation until 1849 was erected here under Duke JULIUS VON BRAUNSCHWEIG. The salt springs were located near the centre of today’s town (street name Am alten Salzwerk, meaning “at the old salt works”). Thereafter the saline was converted into a saltwater spa, making use of the mineral water collected in various shafts and boreholes for curative drinking and bathing treatments. To increase the output of mineral water, an 840 m deep well was drilled in the spa park in 1964/65. It first passed through layers of the Harz Paleozoic, then through the southwards sloping, inclined Harznordrand Thrust and under that the inverted Upper Buntsandstein and Muschelkalk rocks. From the saliniferous Muschelkalk, 2% salt brine with a temperature of 30° C flows into the drilled well shaft. So Bad Harzburg has a thermal spring, as well! From the spa park in Bad Harzburg the Großer Burgberg is easily reached by funicular railway - and a visit to the Haus der Natur (Nature Visitor Centre) is also worthwhile. Using modern media the forest and Nationalpark Harz ecosystems are presented. The introduction to the environmental presentation is an overdimensional “nature library” which deals with the variety of animal and plant life in the Harz.

We leave Goslar heading west along the B 82, following the signs to the Granetalsperre (Grane Valley Reservoir). Doing so we cross through the gravel and pebble landscape of the Haar. The approximately 10 metre thick layer of Pleistocene gravel is easily apparent; the lowermost bed is material from the Harz, over it lies gravel containing nordic material which was transported by glaciers from Scandinavia to the Harz area. Gravel from here was used in construction of the Grane Reservoir. We arrive at Herzog-Julius-Hütte, a settlement which goes back to a smelting works where ore from the Rammelsberg has been smelted since the middle ages. Today arsenic, gallium, germanium, indium and other special metals for the semiconductor and IT industry are produced on the sites of the former smelting works. Up the hill to the right we come to the Grane Valley Reservoir Waterworks. The Grane River Dam was built from 1966 to 1969, primarily to retain drinking water. The exhibit entitled “Water, the special Resource” is worth a visit. The highlight of the exhibit is an 8,000 litre aquarium where fish can be observed in an environment modelled after their natural habitat. From the winch house on the dam we enjoy the distant view of the Harz Border, the North Harz Upthrow and the Innerste Synclinal Valley, which stretch to the forested ridge of the Salzgitter Anticline (salt saddle) in the background. This synclinal valley is the westernmost part of the Subhercynian Basin, that is the Cretaceous syncline structure lying before the Harz and following along the Northern Harz Edge.
For further information: www.harzwasserwerke.de

We drive back to the B 82n and further toward the west to the old smelting community of Langelsheim (exit Langelsheim Ost). On entering the community we turn right in the direction of Jerstedt. The small road brings us to the long geological profile of the Kanstein. The undercut river bank of the Innerste River reveals the series of strata. The Cretaceous profile begins with the Hils Sandstone of the Lower Cretaceous, which lies here discordant on Upper Jurassic clays. After that, shallow strata of Minimus Clay and gravely, greyish-yellow speckled Flammenmergel follow. Following these are limestones of the Lower Muschelkalk, which in turn are followed by Rotpläner and Turon limestones as well as Coniac beds. These were quarried in a large quarry to the right of the road, the Langelsheim Quarry of the Rohstoffbetriebe Oker GmbH & Co. If the strata have been steep to overtilted up to here, now the transition to nearly flat layering can be seen in the profile. Searching for fossils in the Kanstein quarry is worthwhile. It also offers a view of the fissuring and faulting system in the rocks of the area. Along the tectonic structures, movement of larger rock bodies occurred, and, intensified by the influence of tectonic caves, caused rockfall and continuing danger of landslides, making the relocation of the county road neces–sary. At the top of the Kanstein the remains of a Carolingian fortress were found.

Back in Langelsheim, we continue our drive in the direction of Seesen and soon reach the Lutter Basin. Framing this are, in the east, ranges of hills consisting predominately of Hils Sandstone, which in this area is particularly firmly formed and was formerly quarried extensively near Ostlutter. The church in Lutter is an outstanding example of the local stonemasons’ craftsmanship. The forested ridge on the western edge of the Lutter Saddle consists, in contrast, of the hard limestone of the Lower Muschelkalk. To the south the Harz Palaeozoic closes the Lutter Basin. Here the Harznordrand Thrust runs out within a short distance. Lutter became known through the Battle of Lutter on Barenberg which took place here in 1626. The imperial-ligistic troups under TILLY so completely defeated the army of the Danish King CHRISTIAN IV that they had to retreat to Holstein.

Near Hahausen we leave the B 82 and drive along the B 248 in the direction of Seesen to the car park between Neuekrug and the junction with the county road to Bornhausen. We walk back along the bicycle path adjacent the road for 700 m, then left along the asphalt agricultural access road, and, before reaching the railway bridge, along the grass-covered pathway. Here we meet the most northerly branch of the Zechstein Range, which accompanies the Harz along its southern side. Quite near the base of the Zechstein, Kupferschiefer (copper shale) occurs, the metal content of which formed the basis for mining in the Mansfeld and Sangerhausen mining areas (Landmark 12). Encouraged by the economical success here, attempts were made to also obtain Kupferschiefer ore. The geological situation and a too marginal metal content quickly lead to the failure of the New Mansfield Copper and Silver Mining Company. Left are the colliery spoils, on which one can find clumps of Zechsteinkalk and Kupferschiefer. Fossils of fish parts (Palaeoniscus freieslebeni) have also been found here.

As we leave Seesen we turn right in the direction of Gasthaus Winkelsmühle. The Water Trail Winkelsmühle there leads us along an enjoyable walk through the beautiful sinkhole and lake landscape and to the nature protection area “Silberhohl” with its impressive large sinkhole. These sinkholes were formed by the local dissolving of the underground Zechstein gypsum which resulted in the incasion of the overlying Buntsandstein rocks. Many sinkholes are today filled with water.

We have now reached the end of the North Harz Border. Seesen was formerly called Sehusa (= Seehausen, roughly “pond community”). The ponds within the town area are now silted; remains of these water bodies, which resulted in part from sinkholes, can be found e.g. in the Schlossteich (castle pond) behind the city museum. A visit to the museum is worthwhile, not only from a geological point of view. Besides the extensive mining, geo and mineral collection, piano construction is a main feature, as the Steinway & Sons Company originated in this area. Further exhibits deal with the tinwares industry in Seesen; HEINRICH ZÜCHNER produced around 1830 the first German tin can here, by hand.

Ringhotel Goldener Löwe Seesen
www.loewe-seesen.de
+49 5381 933-0

Hotel Winterberg Bad Harzburg
www.solehotels.de
+49 5322 928692

Hotel Tannenhof Bad Harzburg
www.solehotels.de
+49 5322 96880

The map will assist you in planning your own personal georoute around the Rammelsberg. Tours under competent guidance can also be booked (Dr. Steiger, Managing Director of the team of the Harz Mountains regional association’s geogides, DR. STEIGER, Tel.: +49 3944 - 36 90 85 or e-mail: T_Steiger@gmx.de). The Regionalverband Harz e. V. wishes you pleasant relaxing holidays and interesting insight into the geology and the history of the part of that Nature and Geopark Harz which you have just been introduced you.

Translation: Holly Pankow, Dipl.-Geol. Friedhart Knolle
Photos: Bothe, George
Editing: Dr. K. George, C. Linke