Introduction

Effective safeguarding of geoheritage exposed in quarries, whether working or abandoned, is among the greatest challenges faced by geoconservation in general (Prosser et al. 2006; Nita, 2012; Bridgland 2013; Beranová et al. 2017; Erikstad et al. 2018; Marengo et al. 2019; Parkes and Gatley 2018; Prosser 2018; Evans et al. 2023). Active quarrying results in an inevitable conflict of economic and social interests on one hand, and conservation goals on the other one, with consequent irreversible loss of certain geoheritage elements if the former are decided to be a priority. Relevant examples include destruction of karstic features such as caves, sinkhole fillings or paleokarst phenomena, fossiliferous beds within quarried sedimentary rocks, tectonic structures, and sedimentary structures and successions in aggregate quarries (e.g., Bridgland 2013; Prosser 2018; Roberts 2019; Szente et al. 2019; Drápela 2020). It may happen that outcrops of specific rocks or sediments have been completely exploited, leaving no trace of their former existence, despite their considerable palaeogeographic value. Closure of quarries brings about new challenges for geoconservation (Prosser 2018; Drápela 2020; Erikstad et al. 2023). Rehabilitation plans for former quarries may or may not be developed, and some include afforestation, flooding or conversion into a landfill site, with any geoheritage elements left after quarrying being no longer accessible. If left without direct human intervention, natural processes of rock weathering, mass movements, water erosion and vegetation succession begin to play their roles, which may lead to quick disappearance of abandoned quarry faces beneath slope debris and plant cover. In these cases, even if geoheritage elements are not irreversibly lost, they are concealed and unavailable for either scientists or visitors, including geotourists. Further issues include safety of visitors, provision of adequate tourist facilities, protection of the most fragile and/or scientifically most valuable parts of a quarry, and effective monitoring. Therefore, both long-term strategies regarding the future of currently operating quarries and carefully designed management plans for abandoned quarries, if these are identified as worth conservation, are necessary.

Abandoned quarries are not only important for scientists who may now enjoy easy access to key geological localities, hardly accessible at past times of industrial operations. They also have a great potential as geosites, offering unique windows into the three-dimensional architecture of geological units, exposing the record of events which shaped an area over geological timescale, and revealing large-scale structures otherwise not visible at all (Gajek et al. 2019; Todaro 2018). In addition, they provide an opportunity to link stone heritage in situ, exposed in a quarry, with various uses of this resource as a building stone in the surrounding area and, occasionally, far away from site of exploitation. Therefore, open-air exhibitions of quarried stones, highlighting their multiple use, are occasionally arranged close to former quarries (e.g., GRANITkulTOUR trail in the granite Blockheide area in Lower Austria; Migoń et al. 2018).

There are numerous examples of former quarries converted into sites focused on geo-education, equipped with geotrails, interpretation panels, open-air displays of rock types, exhibition rooms, dedicated spaces for outdoor teaching, and the like (e.g., Wrede and Mügge-Bartolović 2012; Tokarczyk-Dorociak et al. 2015; Prosser et al. 2018; Prosser 2019; Frey et al. 2021; Kaźmierczak et al. 2024). An overview of geosite inventories from UNESCO Global Geoparks and other areas with significant geodiversity and geoheritage shows that abandoned quarries are frequently included into the lists of places recommended to visit. Their role is particularly important in areas typified by humid climate, thick soils, and widespread vegetation, which otherwise offer limited insights into geological records.

In this paper we intend to present a turbulent, but finally successful story of former basalt quarries located at Mt. Wilkołak in south-west Poland, within the boundaries of the Land of Extinct Volcanoes UNESCO Global Geopark, approved in March 2024. Their considerable scientific values were long recognized and partial protection has existed for more than 60 years, but ongoing quarrying was a sustained threat and the fate of the main quarry pit after termination of industrial operations was uncertain. However, recent developments associated with quarry rehabilitation (Kaźmierczak et al. 2024) have paved the way to proper safeguarding and effective management of this regionally unique site, which has a potential to become a premier geological locality in south-west Poland. We also believe that learning the history of Mt. Wilkołak may become inspirational for anyone dealing with comparable localities elsewhere, where geoheritage values may be currently under threat. This paper is based on literature review, long-term involvement of the senior author in conservation activities and struggles focused on Mt. Wilkołak, and observation of recent developments. For the presentation of the history of Mt. Wilkołak, an invaluable source of information is a monograph written by a collective of local authors (Gorzkowski 2010) and published in 2010 (in Polish, with English and German summaries).

Study Site

Location and Landscape Setting

(Mt.) Wilkołak is the name of a distinctive hill in the region of Kaczawskie Foothills, in the western part of the Sudetes Mountains, in south-west Poland (Fig. 1). The name translates into English as “werewolf”, although the former German name Wolfsberg would be better translated as “Mount Wolf”, or “Wilcza Góra” in Polish. In fact, the latter is the name of a nature reserve established in 1959 over a small section of the hill, causing a toponymical confusion. The nearest town, a few kilometres to the north, is Złotoryja, a historical town with a range of architectural monuments and close connection with medieval gold mining.

Fig. 1
figure 1

Location of Mt. Wilkołak on the background of geological structure of the region. Boundaries of the Land of Extinct Volcanoes UNESCO Global Geopark are indicated (map courtesy of K. Jancewicz)

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The current altitude of the hilltop is 370 m asl, but older cartographic sources indicate 373 m asl and a figure of 367 m can also be found. The surrounding upland surface is at 260–290 m asl, resulting in a relative elevation of around 100 m. However, except minor slope sections it is not possible to observe the original natural shape of Mt. Wilkołak, which was thoroughly altered by many decades of large-scale quarrying (Fig. 2). The lower slopes are moderately steep, c. 15°, but the middle and upper slopes were likely to be steeper, perhaps up to 40°, as suggested by upward-concave slopes of other basaltic hills in region, which were not reshaped by industrial activity, as well as by old topographic maps (Fig. 3). On the other hand, old drawings show the hilltop having been rather flat. The base of the hill is c. 750 m × 750 m, with the circumference of about 2.3 km.

Fig. 2
figure 2

Deformed silhouette of Mt. Wilkołak from the south. The eastern side of the hilltop is undercut by a quarry closed in 2019. Geological nature reserve is located on the western side (facing the viewer)

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Fig. 3
figure 3

Comparison of German topographic maps at the scale of 1:25,000 documents quarry expansion and associated landscape changes. a Map from 1887, with two inns (Wilhelmsbaude, Wolfsbaude) and no signs of large-scale quarrying, although some local operations must have taken place as suggested by the name Basalt Br. (basalt quarry). b Map from 1914, with a quarry (Basalt Br.) on the western slope and the ramp used to deliver basalt stones to the processing plant. c Map from around 1937. The western quarry was already closed and transport installations on the ramp dismantled, but a new quarry was operating on the eastern slope

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Mt. Wilkołak rises above an undulating water-divide surface, gently sloping in WNW direction, towards the valley of the Kaczawa River. From a geomorphological point of view, this sloping upland is a backslope of a cuesta, supported by sandstones of Late Cretaceous age. The sandstones were pierced through a volcanic vent, then filled with breccia deposits and basaltic lava, which solidified into a plug built of a rock far more resistant than the host sedimentary rock. Subsequent differential weathering and denudation have resulted in the emergence of a solitary basaltic hill, which despite modest relative elevation is a well-recognized landmark, visible from afar.

Geological Context

Mt. Wilkołak is one among many hills in the Kaczawskie Foothills built of rocks of volcanic origin and, in general, basaltic composition (Wocke 1927; Birkenmajer 1967; Migoń et al. 2002; Migoń and Pijet-Migoń 2016). Volcanic activity occurred in the mid-Cenozoic and various radiometric ages of individual basaltic outcrops are available in literature (Badura et al. 2005; Birkenmajer et al. 2002, 2007; Pańczyk et al. 2023). Palaeomagnetic data have also been provided (Birkenmajer and Nairn 1969). All these age determinations constrain the volcanic activity in this part of the Sudetes to the period from the Early Oligocene to the Middle Miocene, spanning ca. 15 Ma. Specific ages obtained for basalts of Mt. Wilkołak are 20.1±0.9 Ma (Birkenmajer et al. 2007; K-Ar method) and 21.3±0.4 Ma (Pańczyk et al. 2023; 40Ar/39Ar method), whereas Badura et al. (2005) dated the nearby outcrop at Mt. Dębina (3.5 km to the east), which yielded the age of 24.5±1 Ma (K-Ar method). In each case only one sample was subject to dating, whereas an earlier study by Śliwa (1967) concluded with the finding that several phases of volcanic activity may have occurred at Mt. Wilkołak, as suggested by the complex pattern of thermal jointing exposed in extensive quarry walls. The relevant timespan of this multi-phase volcanic history was, however, not defined.

The volcanic vent of Mt. Wilkołak cuts through medium- and coarse-grained quartz sandstones of Turonian (Late Cretaceous) age, dipping generally to the west (Jerzmański 1958). These sandstones are of shallow marine origin and formed not very far from the contemporaneous shoreline. Beside occurring in the vicinity of the basaltic hill, large sandstone blocks many tens of metres long are exposed within quarry walls, embraced by the lava. In addition, numerous sandstone xenoliths can be found in the lava and, mainly, in associated breccia deposits.

In the Pleistocene the Kaczawskie Foothills were invaded by the Scandinavian ice sheet at least once, probably twice, during marine isotope stages (MIS) 12 (> 400 ka) and, possibly, also 6 (< 190 ka) (Piasecki 1961; Badura and Przybylski 1998; Kowalski et al. 2018). Regional analysis of the distribution of glacigenic sediments versus altitude suggests that Mt. Wilkołak was overridden by ice during MIS 12, but probably not during MIS 6. However, complete anthropogenic reshaping of the hilltop does not make it possible to discuss the impact of glacial erosion. By contrast, cold-climate (periglacial) deposits from the last glacial period used to be well exposed in the quarry walls, including solifluction sheets, scree and loess, and were documented by K. Maciejak (in Migoń et al. 2002).

Adjacent Geosites

The special position of Mt. Wilkołak in the geoheritage and geotourism context is enhanced by the proximity of several other sites of interest, recognized in the regional inventory prepared for the Land of Extinct Volcanoes Geopark (Inwentaryzacja Geopunktów na obszarze Partnerstwa Kaczawskiego 2019). In the radius of 5 km there occur further volcanic outcrops, either in abandoned quarries (Czerwony Kamień) or representing natural crags (Diablak) (Migoń and Pijet-Migoń 2016), a large outcrop of Turonian quartz sandstone in an abandoned quarry in the village of Jerzmanice-Zdrój, deformed close to a major fault (Leszczyński et al. 2022), several sandstone towers and cliffs next to this quarry, non-karstic caverns formed by weathering and piping in the Drążnica valley, at the foot of Mt. Wilkołak (Migoń 2021, 2024), and extensive sandstone block fields in front of a sandstone cuesta to the east of Wilków (Duszyński et al. 2017). The long history of mining and processing is being brought back to life in the open-air museum in Leszczyna, surrounded by abandoned quarries of Permian sandstones and dolomites, as well as remnants of copper ore mines (Wiśniewski and Horoszko 2013; Stolarczyk et al. 2017), all connected by an educational trail. Altogether, these localities make a distinctive cluster of sites of geoheritage and geotourist interest, which can be easily linked by a network of geotrails.

History

Pre-World war II Recreational use and Limited Quarrying

The dominant position of Mt. Wilkołak in the regional landscape could not have gone unnoticed since very ancient times. German archaeologists reported about stone walls close to the hilltop, interpreted as remnants of a Bronze Age stronghold. It is also possible that the hill, as several others in the region, was a place of worship for pre-Christian communities (Łesiuk 2010). In medieval times the steep-sided hill likely remained forested and not used in any particular way, apart from possibly serving as a vantage point, despite its proximity to the town of Złotoryja. During Napoleonic Wars, in 1813, it played a military role for a while, overlooking the vast stretches of subdued topography which were the theatre of the Battle of Kaczawa, held in late August 1813. Captured by French troops on 23 August, it was regained by Prussians three days later after the defeat of the French forces (Gorzkowski 2010). These events were later commemorated by a monument erected in 1844, dismantled in 1946.

In the first half of the 19th century, in line with the contemporaneous trends towards outdoor leisure activities, Mt. Wilkołak became an obvious recreational spot for the citizens of the nearby Złotoryja. Its popularity rose after the opening of an inn of Wilhelmsbaude in 1844, located at the north-eastern footslope of the hill (Figs. 3 and 4). The pyramidal monument of the Battle of Kaczawa was built nearby and a toboggan run operated in winter months. A path connected the restaurant with the hilltop, but whether the latter was a viewing point and an excursion target is unclear. However, the tourist potential of the place was clearly realized, as testified by the opening of another restaurant close to the hilltop, the Wolfsbaude, in 1882. It was located at the distinct slope break separating the hilltop flat and the steep south-facing slope, hence the adjacent terrace served as a good observation point, with extensive vistas to the south and west. Simultaneously, small-scale recreational infrastructure was developed next to the building by the members of the local tourist organization. An end-19th century topographic map, dated around 1887, shows that no basalt quarrying occurred at that time (Fig. 3a).

Fig. 4
figure 4

Summarized history of Mt. Wilkołak shown as a timeline. Bold indicates key steps in geoconservation, whereas red colour denotes main developments in the industrial history

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This changed in the beginning of the 20th century as testified by the next edition of the topographic map, dated for 1914 (Fig. 3b). A large quarry was already in existence on the south-western slope, immediately below the Wolfsbaude inn. The map suggests that the quarry was c. 250 m long, but in the light of a subsequent map (Fig. 3c) this seems to be an exaggeration and the quarry did not reach as far north. To facilitate transport of basalt blocks a causeway was built to the west of Mt. Wilkołak, connecting the quarry with the processing plant built next to the regional road in the distance 0.7 km. Over time, quarrying expanded towards the south, encircling the hilltop, whereas a side-effect of industrial operations was the origin of a wide anthropogenic bench in front of the quarry face. For reasons remaining unknown, basalt exploitation in the western quarry terminated at some time in the 1920s, maybe even before. The map published around 1937 does not show the causeway as an active transportation route any longer (Fig. 3c), and in 1931/32 the former quarry area (the bench) was developed as an airfield for light aircraft and, particularly, gliders (Fig. 5). In 1941, already during World War II, the airfield grounds and the Wolfsbaude above were sold by the town to one of Nazi-related organizations, Nationalsozialistischer Fliegerskorps (NSFK), which converted the facilities into the training camp for Hitlerjugend, but continued flying exercises. Towards the end of World War II these facilities were destroyed or dismantled, whereas a network of trenches was excavated around the hill (Gorzkowski 2010).

Fig. 5
figure 5

(source: polska-org.pl; access date 28-02-2024)

Mt. Wilkołak on an old postcard, view from the south. One can see the wall of the old quarry in the middle, the adjacent anthropogenic bench to the left and the building of Wolfsbaude restaurant above the quarry.

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In the meantime, however, quarrying began elsewhere on Mt. Wilkołak (Fig. 3c). Various minor-scale attempts were undertaken on the northern slope, but the largest quarry was developed on the east-facing slope in the inter-war period. By the end of the 1930s, it was already c. 200 m long. The older of two inns, Wilhelmsbaude, was closed due to interference with industrial operations.

Post-World War II – Resumption of Quarrying

Major political and social changes in the aftermath of World War II, with the shift of political boundaries, establishment of Polish administration and replacement of German population by the Polish one, opened a new chapter in the history of Mt. Wilkołak. Although ruined remnants of pre-war tourist and recreational infrastructure were soon completely dismantled, the hill itself remained a place of outdoor recreation. However, in 1951 quarrying was resumed in the eastern quarry, which began to expand both towards the hilltop and sideways. Likewise, basalt exploitation recommenced in the long abandoned western quarry, despite voices from the academic community about the uniqueness of outcrops of columnar basalt and their didactic values. As a compromise, it was agreed to terminate stone extraction in 1956, to be followed by establishing legal protection of the old quarry. Since that time, only the eastern quarry continued operation, but its massive scale soon jeopardized the very existence of the hill, including the protected area.

Establishing a Nature Reserve

After a brief period of renewed exploitation in the western quarry in the early 1950s, the site was abandoned by the industry. Due to convenient location, the old quarry was frequently visited during geological excursions as part of university education and its educational values were increasingly realized, especially the clarity and diversity of columnar thermal jointing in basalt were highlighted. A report commissioned in 1956 by the State Council for Nature Conservation from Professor Józef Zwierzycki, a respected authority with experience in investigating volcanic phenomena in Indonesia, included the following quote: “At Mt. Wilkołak we have the record of internal evolution of a volcano, which is rarely seen globally” (own translation, after Maciejak and Gorzkowski 2010). Efforts to enhance the status of the site and ensure its survival proved finally successful in 1959, when a nature reserve was formally established, encompassing the former quarry and part of the hilltop surface above the former quarry wall. However, the protected area was very small, covering only 1.69 ha, which soon proved very inadequate up against the needs of stone extraction industry.

Diverging Pathways: Expanding Quarry and ‘Troublesome’ Reserve

Ongoing operations in an expanding quarry next to the nature reserve set the stage for inevitable conflict between industry and nature conservation, the former being in a privileged position in the developing socialist country. In the 1950s and 1960s, until the mid-1970s the scale of industrial operations was apparently not large enough to put the reserve at imminent risk, although restrictions on access to the reserve and detrimental effects on landscape qualities were noted (Grocholski and Jerzmański 1975). Already at that time it was also suggested that after termination of quarrying the site should be developed for tourism and recreation, as a logical consequence of a region-wide assessment of volcanic outcrops and inclusion of Mt. Wilkołak into the group of most valuable sites (I class). However, expansion and modernization of stone processing plant in 1968–1970 heralded incoming problems.

Increasing threats to the integrity of the reserve clearly emerge from the paper by Złonkiewicz (1985), published a decade later in a specialist journal focused on nature protection, and so with limited impact on decision-makers. The buffer zone of the reserve was reduced from 50 m do 15 m, quarry walls approached the boundary of the reserve, and rockfalls occurred within their oversteepened sections, contributing to even faster quarry wall retreat. Blasting weakened the stability of the rock mass, affecting also the reserve. Over the years the top part of Mt. Wilkołak became more and more reduced in areal extent, which prompted the protagonists of the industry to argue that the narrowed hilltop was increasingly unstable and prone to collapse, and the only way to address the problem would be to remove it completely, exploiting all basalt resources, and flatten the elevation. This would involve the disappearance of the reserve as well. Interestingly, the existence of World War II trenches in the top part of Mt. Wilkołak, misinterpreted as opening fissures due to rock slope instability, was used to support the proposal to grade the hilltop (Złonkiewicz 1985). In the 1980s and 1990s there was a clear pressure from the industry to expand the quarry and to sacrifice the reserve, reflected in several hired consultancy reports recommending formal delisting of the reserve and extension of industrial operations into the western part of the hill (Maciejak and Gorzkowski 2010). As these proposals were not approved, quarrying continued around the reserve, expanding into the NW part, as well as reached lower altitudinal levels, transforming the former hillslope quarry into an ever deeper open-cast pit (Fig. 6a). This in turn led to the origin of quarry walls nearly 100 m high, in heavily and locally irregularly jointed bedrock, thus prone to collapse (which eventually happened in 2019, see below). Moreover, ongoing quarry operations severely limited access to the reserve, which could not be officially entered during working hours of the quarry. For these reasons, a waymarked hiking trail skirted the reserve along the footslope of Mt. Wilkołak and the path to the reserve was not signposted.

Fig. 6
figure 6

Views from the working eastern quarry, taken in 2005. a General view of exploitation levels. A large sandstone block embedded by the lavas is seen in the lower left corner. b “Basaltic rose” – a spiralling pattern of columnar jointing exposed within the highest exploitation level. Note scree cones testifying to ongoing rock disintegration and fall (photographs by P. Migoń)

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However, in fairness it should be pointed out that the nature reserve established in the pre-World War II quarry was not properly managed by relevant nature conservation authorities. In particular, no strategy existed (or was not transformed into action) to ensure that the main values of the reserve will remain visible and accessible. In the humid temperate climate vegetation quickly overtook jointed former quarry faces and adjacent talus, concealing the very geological features for which the reserve was established. This was particularly evident during the vegetation season. Uncritical adoption of the general rule holding that no interference with vegetation should take place in a protected area led to the loss of geoheritage values and gave fuel to voices arguing that the reserve ceased to perform its function. It was only in 2013, when the first comprehensive vegetation clearance in the reserve was executed, revealing again multidirectional jointing patterns and outcrops of breccia materials (Fig. 7).

Fig. 7
figure 7

View of the nature reserve “Wilcza Góra”. a Rock outcrops largely concealed by vegetation (state May 2009). b After vegetation removal in late 2013 (state January 2014) (photographs by P. Migoń)

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Poor management of the reserve led to the situation, in which the working quarry was a much better place to observe geology of the volcanic neck than the reserve. In particular, at some time in the 1970s a picturesque spiralling pattern of basaltic columns was exposed in the quarry wall undercutting the hilltop, soon called ‘the basaltic rose’ (Złonkiewicz 1985). It was c. 20 m high and 40 m wide (Fig. 6b). No similar structure could have been observed in the reserve. Educational visits of geology and geography students into the working quarry were permitted subject to prior arrangement and consequently, general interest of geoscience community to save the reserve and re-expose the rock walls was diminishing. In the early 21st century a stalemate occurred regarding the future of Mt. Wilkołak. On one hand, no one seriously considered delisting of the reserve any longer and there were more and more frequent voices from the local community highlighting not only scientific, but even more so the symbolic values of Mt. Wilkołak as a local landmark that cannot be lost. It was also argued that the site has a potential to become one of the key geosites in the Land of Extinct Volcanoes Geopark, discussed and developed since around 2015. On the other hand, quarrying continued, albeit at a restricted scale, going deeper and sideways.

Termination of Quarrying and What Next

In the early 21st century the scale of quarrying gradually diminished, which was also reflected in decreasing employment in the quarry and processing plant, from nearly 200 people in the 1970s through around 100 in the late 1980s to less than 30 in 2009 (Cetera et al. 2010). Limitations imposed by site conditions (availability of basalt resources, geological-engineering constraints), the proximity of the reserve and increasing power of conservation agencies, and growing environmental awareness among the local population paved the way to the termination of industrial activity. The permission to run the quarry was originally to expire in 2011, but in effect of negotiations between the owner of the plant (a subsidiary of global COLAS enterprise) and the rural municipality of Złotoryja it was agreed to allow for continuation of limited quarrying until the 2020s, after which the owner would execute complete rehabilitation of the quarry grounds and hand the site back to the municipality. Different options were discussed, including afforestation and conversion into a landfill site, but the huge geotourist potential was increasingly argued by different groups (local activity groups, tourism industry, conservationists, scientists), at different fora. The development of new communications channels and social media certainly helped to raise the issue and exert appropriate pressure. The end of industrial operations occurred earlier than expected, being caused by massive rock-slope collapses of the quarry wall in August 2019 and July 2020. These events showed clearly that the site is inherently unstable and any further exploitation would put people and infrastructure at serious risk (Kaźmierczak et al. 2024). Consequently, a decision was issued to terminate quarrying and rehabilitation towards tourist and recreational use began, opening a new chapter in the turbulent history of Mt. Wilkołak. This major breakthrough coincided with the application of the Land of Extinct Volcanoes Geopark to become a UNESCO Global Geopark, creating an opportunity to add a new, spectacular geoheritage site to the list of geosites within the Geopark.

Site (Quarry) Description

The outcome of the complicated past of Mt. Wilkołak is the presence of two adjacent, yet disconnected former quarry areas. They will be described in more detail below, under the headings of “western quarry”, applicable to the industrial area abandoned already before the World War II, only briefly used afterwards, and subsequently protected as a nature reserve, and “eastern quarry”, denoting a much larger area subject to quarrying until late 2010s and recently rehabilitated (Fig. 8).

Fig. 8
figure 8

(source: geoportal.gov.pl; access date 28-02-2024)

Annotated topography of Mt. Wilkołak and its vicinity on a LiDAR DTM. Note that the model shows the situation around 2012, with the quarry and processing plant still in operation. Details of relief in the eastern quarry have changed since (compare with Fig. 10).

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Western Quarry

The western quarry in its current shape consists of an arcuate former quarry face of the total length of c. 140 m, in front of which a large bench extends, much longer than the quarry face itself (more than 180 m long, nearly 100 m wide). Taken together, the occupy c. 2 ha. The height of the face varies from a few metres at the NW end to 35 m in the highest, central part. However, vertical rock walls are not very common and occupy small sections only. Over most of the quarry face they have been replaced by sloping surfaces, with bedrock in the upper sections and scree in the middle and lower sections, partly vegetated. The quarry face exposes both solid lava and breccia deposits, with lower slope gradient in the latter.

The most interesting outcrops, also most close to the observer, are located in the north-western section, where the quarry face is parallel to the original slope of the hill, being thus its cross-section (Fig. 9a). Here one can see various arrangements of columns formed due to thermal stresses, from perpendicular to the slope to almost parallel ones, and how they influence slope morphology. In particular, mid-slope crags show to be associated with columns steeply dipping into the slope, whereas smooth slope sections are underlain by columns lying broadly parallel to the slope. In the central part one can see breccia deposits, subject to gravitational downslope movement (Fig. 9b). They contain numerous xenoliths of Cretaceous sandstones, some up to 1 m long, distinguishable by their light colour.

Fig. 9
figure 9

Nature reserve “Wilcza Góra”. a Cross-section of an original hillslope shows changing relationships between the dip of columnar joints (dashed lines) and slope angle (dotted line). b An outcrop of breccia materials, with sandstone xenoliths distinctive by their light colour (photographs by P. Migoń)

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Fig. 10
figure 10

The rehabilitated (eastern) quarry – general view towards the flattened hilltop of Mt. Wilkołak. Note huge scree cones originated from catastrophic rock-slope collapses of quarry walls in 2019 and 2020 (photograph by P. Migoń)

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Eastern Quarry

The eastern quarry is much larger than the western quarry, reflecting nearly 100 years of intensive exploitation of basalt resources. Moreover, the relief of the quarry is different. In contrast to the western one, where exploitation never went below the level of the bench adjacent to the quarried face, basalt extraction in the eastern quarry involved considerable deepening of the quarry floor in respect to the adjacent terrain, resulting in a pit which is nearly 60 m deep (Fig. 10). The total height measured between the top of Mt. Wilkołak and the bottom of the pit is c. 110 m. The quarried area is 450 m long in N–S direction and up to 325 m wide, with the total area of nearly 9 ha. Adding an adjacent area of levelled ground to allow for further industrial operations and numerous spoil heaps, the area nearly doubles, to 17 ha.

Fig. 11
figure 11

Comparison of Google Earth images taken in 2017 and 2023 shows the extent of topographic transformation of the quarry face by catastrophic rock-slope collapses in 2019 and 2020 (white rectangle). Note also complete dismantling of the processing plant (right) (source: Google Earth; access date 2024-02-28)

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The quarry pit consists of two parts, separated by an ‘island’ of W–E orientation. This elevation is built of thermally-altered Cretaceous sandstone, which forms a large xenolith within basalt and was left as a stone resource of no use (Fig. 11a). The northern part is slightly smaller and less deep, with the former exploitation fronts in the north and west. The northern face used to show an excellent example of a 2-m-thick contorted lava apophysis intruded into sandstone (Fig. 12), but it has been subsequently destroyed. Today this section shows irregularly jointed basalt with columns of different orientation and deep pockets of breccia deposits, and some sandstone in the NW corner. The southern pit is larger and deeper, facing the main quarry wall which undercuts the hilltop of Mt. Wilkołak (Fig. 10). The sheer height of this face, more than 100 m, used to be divided into several sections separated by narrow benches, but the massive rock-slope collapse in 2019 reshaped the slope and produced a large talus cone, now constituting approximately two-thirds of the slope height (Fig. 11b). The collapse brought a demise to the famous ‘basaltic rose’ and concealed regular colonnades of columnar joints in the bottom part of the pit, but vertical and steeply inclined columns are still evident in the remaining portions of the quarry face. Combining observations from the northern and southern pit one can notice the presence of vertical columns in the central part of the plug and their inclined position towards the margins of the plug. The opposite, west-facing sides of the pit expose mainly thick breccia materials, with some lava both above and below the breccia deposits (Fig. 13). Basalt columns here tend to be inclined rather than standing upright.

Fig. 12
figure 12

Archival photograph (spring 2005) of the northern wall of the eastern quarry, with basaltic veins intruding into the host Cretaceous sandstone (photograph by P. Migoń)

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Fig. 13
figure 13

Thick breccia deposits and basaltic lavas exposed in the eastern wall of the rehabilitated quarry. Open-air exhibition of rock specimens is located above (photograph by P. Migoń)

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Recent Developments

Quarry Rehabilitation

Following the decision to terminate quarrying and dismantle the processing plant, COLAS enterprise began rehabilitation works in the eastern quarry. In the first phase quarry equipment was removed and buildings were demolished, except two mobile air blast shelters, left as technical monuments. In the next steps vegetation was removed from places where it concealed valuable rock outcrops, dangerous sections of the quarry (vertical faces, unstable scree slopes) were put off-limits, paths for visitors renewed, observation platforms graded, and railings built along quarry edges. Educational facilities were erected in designated places (see below). Rehabilitation embraced 30.5 ha, at the total cost of approximately 1 million Euro (www.24legnica.pl). According to the rehabilitation master plan, biological revitalization of grounds adjacent to the quarry pit will follow, including afforestation of part of post-industrial wasteland (Kaźmierczak et al. 2024).

Access

After rehabilitation, access to the former mining area is free, but subject to certain restrictions arising from safety considerations. Most former quarry walls are highly unstable, subject to both detachment of individual stones as well as more voluminous rock-slope collapses, especially in the southern pit of the eastern quarry. Likewise, slopes in breccia deposits, although not vertical, are not stable, modelled by dry avalanches, shallow slides, mudflows and surface runoff. Therefore, direct access to the former quarry walls is not possible, as is standing on the edges of the walls. Areas accessible for visitors include dirt tracks above the northern and eastern edge of the pits, with a few observation points equipped with interpretation panels, and a ramp (former quarry road) going down to the sandstone ‘island’ inside the pit (Fig. 14). On its levelled top an observation platform was prepared and surrounded by railings, allowing for better views of the main quarry wall. However, no further walk is permitted.

Fig. 14
figure 14

Former access road to the quarry floor, now a path leading to the observation platform erected on the remnant of Cretaceous rock within basalt. Scree from rock-slope collapses is immediately behind (photograph by P. Migoń)

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In the western quarry regulations of the nature reserve apply. According to the Polish law, visiting nature reserves is only possible using designated trails. As none has been marked in the “Wilcza Góra” reserve, visitors cannot enter the reserve and any climbing of the quarry walls or to the hilltop is forbidden. However, as the reserve is very small, geological outcrops can be easily seen from a path which runs in front of the protected area. A dirt track traversing the NW slope of Mt. Wilkołak provides connection between the eastern and western quarries.

Otherwise, access to the site is not subject to any temporal restrictions at present. The nearest parking lot is situated 400 m from the quarry edge, next to the former administrative building of the quarry. This in turn is located less than 2 km from the centre of Złotoryja. The western quarry can be also accessed from the nearby village of Jerzmanice-Zdrój, first using a marked hiking trail, but after it skirts the hill along its base, one would need to continue without signposting to reach the nature reserve.

Recreational Facilities

Following rehabilitation, the quarry is now safe to visit and can be used for various recreational purposes. In a few places, specifically at vantage points over the quarry pit, wooden tables and benches were built, allowing for both rest and outdoor education. On an elevated platform above the main pit a picnic ground was arranged, with a wooden shelter with tables and fireplaces. Special facilities are the run for bicycle motocross and concrete graffiti wall (Kaźmierczak et al. 2024), whereas a children’s playground is in plans. As a next step, a 2-km-long single track will be traced and connected with an existing biking trail around the town of Złotoryja.

In the future, the grounds next to the quarry are intended to be used for various recreational, sport and cultural events, including music performances and outdoor cinema shows. However, for this to happen, further investment is necessary, including sanitary facilities, electricity and water supply, and sewage disposal.

Educational Content

Alongside recreational facilities, various provisions enabling for learning experience have been set up within the former quarry. These include information panels about the site itself, erected in several places within the area, and an open-air exhibition of rock specimens from different active quarries located in south-western Poland.

Panels address various themes. The largest group consisting of eight panels standing in a row, showcasing the history of the locality since the military history of the early 19th century, when the Battle of Kaczawa was held in the vicinity, through recreational use prior to World War II, the history of quarrying, up to the most recent termination of mining activity and conversion into recreational grounds (Fig. 15). Geology and basalt resources of Mt. Wilkołak are explained on two panels on the observation terrace in the quarry floor, whereas another observation deck on the northern rim of the pit has one panel focused on biotic world and another one providing an overview of geological and geomorphological history. On the eastern edge of the quarry pit, next to the stone-and-brick shelter once used during controlled blasting, another panel details blasting techniques used during stone quarrying. Finally, a panoramic aerial view of the surrounding countryside is presented, although annotations are limited to the names of terrain elevations. Each panel is bilingual, containing a summary in English. In terms of design, they use simple forms of expression and include a narrative text and, mainly, reproduced historical graphics and photographs (Fig. 15). Diagrams and cross-sections are used to facilitate understanding of geology and geomorphological context of the locality. Unfortunately, none of the panels includes a sketch map of the locality. The texts themselves are quite comprehensive, not limited to a few general statements, whereas their arrangement in long paragraphs, with only occasional use of bold font to highlight key terms, and the clear focus on facts rather than entertaining dialogue with the reader, may not appeal to everyone. In terms of content, the panels will likely satisfy the needs of tourists motivated to learn but the impact on casual visitors, with limited a priori background, is less certain.

Fig. 15
figure 15

Educational facilities in the rehabilitated quarry. a Series of panels presenting the history of Mt. Wilkołak and stone industry. b, c Two sample panels (photographs by P. Migoń)

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A different part of the educational content of the locality is the exhibition of rock specimens. The open-air gallery extends over 200 m and includes 44 stations, each consisting of a rock block weighing from 1 to 3 tonnes and a panel detailing rock characteristics, its industrial use and, if applicable, other information (Fig. 16). In contrast to panels about Mt. Wilkołak, those accompanying the rock gallery are in Polish only. The exhibition begins with basaltic rocks from different quarries in the region (11 specimens), followed by one gabbro block, granitoids (13), trachyandesites (5), metamorphic rocks such as gneiss, greenschists and marble (11), and sandstones (3). One should note that the display does not exhaust the variety of rocks quarried in SW Poland. For example, limestones and rhyolites are missing.

Fig. 16
figure 16

Open-air exhibition of rock types quarried in the region. a General view. b Each rock specimen is accompanied by an information panel. c Close-up of a panel (photographs by P. Migoń)

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By contrast to the rehabilitated quarry, at the time of writing the Wilcza Góra Nature Reserve on the western side of Mt. Wilkołak lacked any educational facilities.

Challenges for the Future

Managing the Rehabilitated Quarry

Site conditions at the moment (early 2024) are excellent in terms of both safety and visibility of geological features, allowing the visitors to have high-quality experience. However, these two aspects are also the major management issues for the future, require constant monitoring and preparedness for emergency reactions, including ‘emergency budget’. Safety is of paramount importance given the morphological features of the rehabilitated quarry such as dangerous edges of former exploitation levels, high rock cliffs, steep and unstable scree slopes, and the risk of falling stones. The current railings and protective fences are robust enough to withstand atmospheric conditions, but may suffer from vandalism and any missing elements should be replaced as quickly as possible. Likewise, the state of access roads needs to be monitored. To maintain visibility of geological exposures is a major issue in humid temperate climate (Różycka and Migoń 2018), as pioneer vegetation quickly establishes itself on scree slopes, minor rock ledges, and in cracks. Experience from the “Wilcza Góra” nature reserve, but also from many localities elsewhere in the region, shows that outcrops, if not subject to regular vegetation clearance, may become completely overgrown in less than a decade. Considering the size of the area it is probably unrealistic to apply vegetation clearance everywhere and the current appearance of the former quarry is inevitable to change, but key geological sections should be identified and maintained in good visibility conditions. These particularly include outcrops of breccia materials, Cretaceous sandstones, sandstone/basaltic lava contacts, and Quaternary cover deposits (the latter currently hardly visible at all), all prone to fast expansion of vegetation.

Summing up, a management plan addressing the above challenges, analogous to ones required for protected areas, is necessary. It should identify risks relevant to various timescales, set up principles of site monitoring, outline remedial action, and define responsibilities, following good practice developed elsewhere (Prosser et al. 2006, 2018; Evans et al. 2023).

A separate issue is how to manage the grounds left after dismantling of the processing plant, at the eastern footslope. Currently it is a vast open area, but it may be developed for commercial purposes, hosting various service and recreational facilities. Location by the road and at a certain distance from the quarry is advantageous, and any new infrastructure would not visually interfere with the quarry and its geoheritage values.

Future of the Conservation area (Nature Reserve)

The situation is somewhat paradoxical as, in theory, it is the nature reserve that should be the most valuable part of a larger area. At Mt. Wilkołak this is no longer the case and the rehabilitated former quarry offers much better and more attractive insights into the structure of the volcanic plug than the rock outcrops in the reserve. This might result in voices questioning the existence of the reserve and calling for its delisting, which would be detrimental for both the site itself, exposing it to the risk of intrusive infrastructural development, as well as for the image and practice of nature conservation policy in general. At the moment it does not seem likely, but the relevant stakeholders should be on alert. An opposite solution could be expansion of the reserve to cover the entire hill, but this is not very likely either, implying various access limitations, changing priorities regarding the use of the site, and transfer of assets and responsibilities from the local municipality to the governmental agency. Thus, status quo will be probably maintained for some time from now.

Consequently, the strategy for the future should explore how these two adjacent areas, but under different management regimes, may work together. Opportunities for enhancement of the geo-educational content of the locality as a whole are developed in the next sub-section, but it is evident that periodic vegetation clearance is necessary in the reserve to maintain the outcrops available for viewing (an interval shorter than 10 years is recommended). A clearly marked path through the reserve should be outlined, complying with the general regulation that only designated paths may be used in nature reserves. Clearance of vegetation at the edge of the anthropogenic bench (former airfield) would allow a viewing terrace to be built, with the panoramic vista towards other volcanic elevations in the region. In this context it needs to be recalled that the remains of the hilltop part of Mt. Wilkołak, although they do offer the views, are unsuitable for this purpose because of safety reasons and should remain off-limits.

Enhancing Geo-Education

On-site interpretative facilities available at present are comprehensive and thematically diverse, but are apparently targeted at one specific group of visitors, motivated to learn and hence, prepared to read rather long stories presented on panels (see above). They are probably less engaging for people with casual interest, teenagers and kids. Although erecting more panels does not seem a good option, as there are many already, exploration based on non-intrusive tools such as apps, quests and games addressed to schoolchildren are options worth to implement. However, one or two extra panels to show the views of different sections of the quarry faces with explanatory annotations (missing at present) can be added along the quarry edge in the eastern part. There is also a potential to develop virtual tours and web-based animations of volcanic history, similar to those presented by Rapprich et al. (2017) for the volcanic localities in Czechia. These may be more appealing to visitors with limited background, but keen to play with modern technologies. It is also discussed that a modest visitor centre can be established near the entrance to the quarry, using an old quarry administration building, and this may host further educational content, including an exhibition to show the wider regional context of basaltic volcanism at Mt. Wilkołak, within the Land of Extinct Volcanoes UNESCO Global Geopark and beyond.

Another challenge is to establish an educational programme focused on the nature reserve and to link it with the one present in the former quarry pit, so it is complementary rather than a duplicating one. As indicated before, the structure of the volcanic conduit and its contact with the host sandstone are better exposed in the eastern quarry, making it more suitable to develop the volcanism theme. However, the hillslope cross-section (Fig. 10a) exposed in the reserve offers an opportunity to explore relationships between geology and geomorphology, i.e., how the arrangement of basaltic columns influences the shape of the slope. Other possible options are vegetation succession in former mining areas, so linking with the biodiversity theme, and history of the hill, represented here by the anthropogenic bench of a former spoil heap, re-used as an airfield prior to World War II. In this way, abiotic – biotic – cultural issues can be combined into one coherent interpretation programme, in line with the ABC concept advocated for geoparks. Broader issues related to the significance of old quarries as conservation targets is another option.

Opening of the former quarry as a geosite also builds a good foundation to connect Mt. Wilkołak with adjacent sites of interest, both physically, by means of a designated geotrail, and thematically. It would be useful to recreate an educational trail from Jerzmanice-Zdrój to Mt. Wilkołak, existing briefly in the 1980 and then, in a new design, in the 1990s, but sadly devastated afterwards. A range of geoscience themes can be addressed along a trail which would only be 3 km long or so, including tectonics, volcanism, lithological diversity (sandstone, basalt), geomorphology (crags, fluvial erosion, non-karstic caves, Quaternary history), quarrying and use of stone resources. The risk of vandalism can now be partially overcome through the use of mobile apps and QR codes instead of large interpretation panels, although these seem now more respected. Such a trail, if executed, would surely become one of the highlights of the Land of Extinct Volcanoes UNESCO Global Geopark.

Conclusions

The history of Mt. Wilkołak illustrates multiple issues related to the interface between geoheritage, effective geoconservation, and quarrying industry. Initially appreciated as a local landmark and developed as a suburban recreational ground, without much consideration of its values as a witness of Cenozoic volcanism, it began to be transformed by basalt exploitation since the beginning of the 20th century. Quarry operation changed the appearance of the hill, but it also exposed an internal structure of the volcanic plug, with multidirectional columnar jointing, later interpreted as the evidence of multi-phase activity. Scientific and educational significance prompted conservation proposals and in 1959 a small geological nature reserve was established. However, poor management of the reserve, evidently arising from insufficient understanding that conservation guidelines for biotic and abiotic nature cannot be identical if conservation targets are to be achieved, coupled with the expansion of a new quarry elsewhere within the hill, caused a decades-long struggle to maintain the reserve and save the hill from total disappearance due to quarrying. Paradoxically, ongoing large-scale industrial operations were revealing more and more interesting geological structures, including impressive palisades of vertical basalt columns, spiral structures (‘stone roses’) and contacts with the host sandstone rock, enhancing the value of the site for geosciences and, potentially, for geo-education and geotourism. The work towards a geopark in the region, accelerated in the mid-2010s, resulted in additional pressure to use the former quarry as a geosite rather than anything else after termination of industrial activities. Another paradox occurred in 2019, when a rock-slope failure destroyed valuable columnar jointing patterns, but prompted closure of the quarry several years earlier than planned. Rehabilitation started, implementing an option to convert the former quarry into a recreational and educational site, and was completed in spring 2023, signalling the final victory of conservation. However, new challenges have emerged, including the vision for the nature reserve, which will need to be addressed in the near future. Nevertheless, the Land of Extinct Volcanoes UNESCO Global Geopark now features a first-class geosite, which due to its large size, a variety of exposed geological features, and well-designed access facilities offers some of the best insights into the structure of a volcanic vent in Central Europe.