Our study site was located in a post-exploitation field at the border of Bytom and Tarnowskie Góry in Upper Silesia, southern Poland, which features a large number of mining shaft remains of various sizes and relief. The information on the history of mining in this area is limited to historical sources, which indicate that lead ore (galena or lead glance) and silver were mined and smelted in this area from the 12th to 20th centuries (Drabina, 2000). In the late 12th century, an intense mining activity was already in existence near Bytom. Numerous historical evidence of mining in contemporary districts: Radzionków, Bobrowniki Śląskie – Piekary Rudne, Repty, and Tarnowice Stare, not far from the later city of Tarnowskie Góry, have been documented from the years 1229, 1369 and 1449 (Nowak, 1927). The first historical mention of the locality of Repty dates back to the decree of 1201 (ibid.). After the Mongol invasion in 1241, which resulted in a significant depopulation of the country, leaving only a few families in Repty, Duke Władysław granted mining privileges to Repty in order to revitalise the declining mining industry caused by the invasion. In the 16th century, mining in this area was highly intensive, and historical records document that during this period there were years when over 500 shafts were constructed (Nowak, 1927). Unfortunately, detailed historical documents are not always available, and thus it is necessary to determine the age of historical mining remains using absolute chronology methods. Precise dating of these structures allows for drawing conclusions about the development of mining in this area, but in a broader context, it is important for studying the relationship between humans and the environment.
The present study aimed to investigate the historical ore mining remains in Tarnowskie Góry. To achieve this objective, the shafts sediments were investigated using absolute dating methods such as radiocarbon dating and optically stimulated luminescence (OSL). Additionally, the surface layer of the sediment was examined for the presence of fallout radioisotopes, namely 137Cs and 210Pb. Furthermore, the remnants of old construction wood found in the excavation were examined using dendrochronological analysis.
The study site (50°23′56.10″N; 20°18′44.26″E) is located in southern Poland near the Tarnowskie Góry city. This area lies on Tarnowskie Góry Hummock, which is a part of Silesian Upland (Kondracki, 2013). This area has undergone anthropogenic transformations, as mentioned earlier, since the early Middle Ages, and underwent significant intensification by the 16th century. The post-mining area in the vicinity of Tarnowskie Góry has been inscribed on the UNESCO World Heritage List, and LIDAR images reveal over 13,000 objects that are remnants of historical mineral extraction. These objects include remnants of mining shafts, which are generally of small dimensions (2–10 m), although larger structures are also present in the field (11–25 m) (Malik
Samples for 14C and OSL dating were collected from three excavations as shown in
A total of 12 samples were taken from the site, 7 of which were sediments containing pieces of charcoal, whereas the remaining 5 were wood. Sediment samples were examined under a microscope to extract possible pieces of charcoal. For samples GdA-6976, GdA-6977 and GdA-6978 it was proved impossible, as the sediment was very dense, and thus the samples were dissolved in ultrapure water and filtered through an 250 μm sieve to extract the charcoal. Samples GdA-6975 and GdA-6976 were both divided into two subsamples, because other organic remains were found in them in addition to charcoal. Those remains, however, were deemed modern, and therefore were not treated further. The charcoal samples were then subjected to an acid–base–acid (ABA) preparation (de Vries and Barendsen, 1954). The first step was acid wash in 0.5 M HCl for 1 h to remove carbonate contaminants, and then they were rinsed with ultrapure water to neutral pH. The next step was alkali wash in 0.1 M NaOH for 1 h for dissolving humic acids and after that the samples were rinsed with ultrapure water again. The last step applied was another acid wash in 0.5 M HCl for 1 h to remove any possible contamination with modern carbon and rinsing with ultrapure water to neutral pH. Next, the samples were dried at 60°C overnight. Acid and alkali washes were performed at temperatures ranging from 75°C to 85°C. After chemical preparation, the samples were weighted in tin boats and subjected to graphite preparation using an AGE-3 system, equipped with an elemental analyser VarioMicroCube by Elementar (Nemec
The measurements were performed at the 14C and Mass Spectrometry Laboratory in Gliwice with the AMS system MICADAS (Synal
For OSL dating, nine samples from the outcrops of filling of three historical shafts were collected. The samples for OSL dating were collected with the use of steel tubes to protect the samples from sunlight (see
To determine the age of the collected samples, an OSL was used, which is widely used for various kinds of sediment samples and archaeological artefacts. OSL dating was conducted at the Gliwice Luminescence Laboratory (Moska
Samples for OSL dating were treated with 10% HCl and 10% H2O2 for 48 h to remove carbonates and organic material, respectively. Next, quartz was extracted from the 125–200 μm grain fraction by using density separation (sodium polytungstate). Finally, quartz grains were etched using 40% HF to remove their outer layer (Aitken, 1985, 1998). After etching, they were washed in HCl (20%) to remove any precipitated fluorides. All treatment was conducted under subdued red light. To determine the equivalent dose, a Riso TL/OSL DA-20 reader with a calibrated beta source of 90Sr/90Yr was used. The standard single aliquot regenerative (SAR) procedure (Murray and Wintle, 2000) was employed for the analyses. The final equivalent dose values were calculated for all samples using the Central Age Model (CAM) (Galbraith
To establish the dose rate, activities of radioisotopes in the samples were measured with the aid of high resolution gamma spectrometry. Before measurement, all samples were dried, homogenised, placed in measurement containers γBEAKER and stored for a minimum of 3 weeks to ensure radioactive equilibrium in U-decay chain (Poręba
In addition to 14C and OSL dating, several other analyses were performed. This included the analysis of 137Cs and 210Pb, dendrochronology for the remains of plank found at the bottom of the filling of shaft number 3, and the archaeological analysis of striped flints found in the fillings of the shaft.
Only one timber sample was available for dendrochronological dating. The board was identified as oak, which is considered a species suitable for dendrochronology; accordingly, standard dendrochronological methods were followed (Baillie, 1982). Tree rings were measured from pith to bark edge using the LINTAB device to a precision of 0.01 mm. For cross-dating, data were processed using the software TSAP (Rinn, 2010), where several common and broadly accepted statistics were used: coefficient of coincidence ‘Gleichläufigkeit’ (Glk), t-value (after Baillie-Pilcher and Holstein) and Cross Date Index (CDI). According to Wigley
The 137Cs (half-life 30.1 years) is a fallout radionuclide that entered the environment as a result of nuclear weapons testing and the Chernobyl nuclear power plant accident. Its presence allows for the study of contemporary geomorphological processes. On the other hand, 210Pb (half-life 22.2 years) is a naturally occurring isotope that is produced through successive radioactive decay in the U-decay chain. The isotope 210Pb is formed as a result of the radioactive decay of 222Rn, which is a daughter product of 226Ra. 210Pb that is produced in situ from 226Ra is referred to as supported, while 210Pb originating from atmospheric fallout is called unsupported (or 210Pbex). The measurement of unsupported 210Pb is widely used to study sediment accumulation rates in various environments. The activity of unsupported 210Pb is typically determined by subtracting the activity of supported 210Pb, which is derived from the daughters of 226Ra, from the total 210Pb content in a given soil or sediment sample (Mabit
The striped flints found in shaft 3 were subjected to archaeological analysis, which did not reveal any evidence of human modification on them.
The results of radiocarbon dating are shown in
Results for 14C analysis. Sample information, carbon content, radiocarbon ages and calibrated age ranges (68.3% and 95.4% probability) are provided.
REP/1 | 14C/REP/1/1 | GdA-6972.1.1 | Charcoal | ABA | 0.985 | 396 ± 25 |
68.3% probability 1445 AD (62.1%) 1495 AD 1600 AD (6.2%) 1610 AD 95.4% probability 1440 AD (76.7%) 1525 AD 1585 AD (18.8%) 1625 AD |
14C/REP/1/2 | GdA-6973.1.1 | Charcoal | ABA | 0.985 | 378 ± 25 |
68.3% probability 1455 AD (49.1%) 1505 AD 1595 AD (19.2%) 1620 AD 95.4% probability 1445 AD (61.8%) 1525 AD 1570 AD (33.6%) 1635 AD |
|
14C/REP/1/3 | GdA-6974.1.1 | Charcoal | ABA | 1.000 | 333 ± 25 |
68.3% probability 1495 AD (19.8%) 1530 AD 1550 AD (35.1%) 1600 AD 1610 AD (13.3%) 1635 AD 95.4% probability 1480 AD (95.4%) 1640 AD |
|
REP/2 | 14C/REP/2/1 | GdA-6975.1.1 | Wood | ABA | - | - | - |
14C/REP/2/2 | GdA-6976.1.1 | Charcoal | ABA | 0.995 | 404 ± 25 |
68.3% probability 1445 AD (68.3%) 1490 AD 95.4% probability 1435 AD (82.3%) 1515 AD 1590 AD (13.2%) 1620 AD |
|
14C/REP/2/3 | GdA-6977.1.1 | Charcoal | ABA | 0.459 | 788 ± 55 |
68.3% probability 1215 AD (68.3%) 1285 AD 95.4% probability 1050 AD (1.2%) 1075 AD 1155 AD (93.6%) 1305 AD 1370 AD (0.6%) 1380 AD |
|
REP/3 | 14C/REP/3/1 | GdA-6978.1.1 | Wood | ABA | 0.980 | 211 ± 25 |
68.3% probability 1650 AD (24.9%) 1680 AD 1740 AD (5.2%) 1750 AD 1760 AD (38.2%) 1800 AD 95.4% probability 1645 AD (31.9%) 1685 AD 1730 AD (54.9%) 1805 AD 1925 AD (8.6%)... |
14C/REP/3/2/A | GdA-6979.1.1 | Wood | Cellulose | 0.989 | 324 ± 25 |
68.3% probability 1510 AD (13.5%) 1530 AD 1535 AD (42.0%) 1595 AD 1615 AD (12.8%) 1640 AD 95.4% probability 1490 AD (95.4%) 1645 AD |
|
14C/REP/3/2/B | GdA-6979.2.1 | Wood | ABA | 0.985 | 343 ± 25 |
68.3% probability 1490 AD (23.0%) 1525 AD 1555 AD (45.3%) 1635 AD 95.4% probability 1475 AD (34.5%) 1530 AD 1535 AD (60.9%) 1640 AD |
|
14C/REP/3/3 | GdA-6980.1.1 | Wood | ABA | 0.994 | 338 ± 25 |
68.3% probability 1495 AD (21.5%) 1530 AD 1555 AD (32.6%) 1605 AD 1610 AD (14.2%) 1635 AD 95.4% probability 1475 AD (95.4%) 1640 AD |
|
14C/REP/3/4 | GdA-6981.1.1 | Charcoal | ABA | 0.980 | 344 ± 25 |
68.3% probability 1490 AD (23.4%) 1525 AD 1555 AD (44.8%) 1635 AD 95.4% probability 1470 AD (35.1%) 1530 AD 1535 AD (60.3%) 1640 AD |
|
TG | 14C/TG-1 | GdA-7058.1.1 | Charcoal | ABA | 0.990 | 384 ± 25 |
68.3% probability 1455 AD (53.1%) 1505 AD 1595 AD (15.2%) 1620 AD 95.4% probability 1445 AD (66.8%) 1525 AD 1570 AD (28.7%) 1630 AD |
14C/TG-2 | GdA-7059.1.1 | Wood | ABA | 0.985 | 1 102 ± 25 |
68.3% probability 895 AD (27.2%) 925 AD 950 AD (41.1%) 995 AD 95.4% probability 885 AD (95.4%) 995 AD |
ABA, Acid–base–acid.
The number of tree rings present on board was 55, a number that allows for dating of oak. To obtain the absolute date, this floating sequence was cross-dated against relevant, local oak tree-ring chronology from Upper Silesia covering the time span 1540–2010 AD (Opała and Mendecki, 2014 and unpublished earlier part of this reference chronology). The oak board was successfully dated by means of dendrochronology, as suggested by positive and statistically significant values of cross-dating (
Results of dendrochronological dating of construction wood.
1640 | 1695 | 63 | 58 | 5.2 | 3.2 | 3.2 | 20 |
Glk, Gleichläufigkei; CC, Cross correlation;, TV, T value; TVB-P, T value Baillie-Pilcher; TVH, T value Hollstein; CDI, Cross Date Index.
The results of activity of natural isotopes, dose rates, equivalent doses and OSL ages for the collected samples are summarised in
Summarised results of activity concentrations measurement, dose rate calculation, equivalent doses and OSL ages for collected samples. All measured values reported with standard deviation.
REP/1 | OSL/Rep/1/1 | GdTL-4584 | 60 | 13 | 24.5 ± 0.8 | 98.1 ± 1.9 | 74.7 ± 7.6 | 2.362 ± 0.083 | n/a | n/a |
OSL/Rep/1/2 | GdTL-4585 | 90 | 8 | 14.7 ± 0.5 | 14.2 ± 0.7 | 154 ± 12 | 1.148 ± 0.047 | 247.8 ± 9.6 | 216 ± 12 | |
OSL/Rep/1/3 | GdTL-4586 | 101 | 23 | 31.8 ± 1.0 | 73.4 ± 1.6 | 305 ± 24 | 2.492 ± 0.087 | 316 ± 15 | 127.7 ± 7.5 | |
REP/2 | OSL/Rep/2/1 | GdTL-4587 | 54 | 5 | 13.3 ± 0.5 | 16.0 ± 0.5 | 323 ± 25 | 1.724 ± 0.079 | 20.45 ± 0.86 | 11.79 ± 0.74 |
OSL/Rep/2/2 | GdTL-4588 | 92 | 8 | 7.5 ± 0.3 | 9.0 ± 0.4 | 206 ± 16 | 1.089 ± 0.050 | 18.86 ± 0.74 | 17.3 ± 1.1 | |
REP/3 | OSL/Rep/3/1 | GdTL-4589 | 45 | 26 | 39.3 ± 1.1 | 49.4 ± 0.8 | 290 ± 22 | 2.196 ± 0.075 | 5.59 ± 0.45 | 2.47 ± 0.22 |
OSL/Rep/3/2 | GdTL-4590 | 65 | 18 | 39.7 ± 1.2 | 69.2 ± 1.4 | 343 ± 27 | 2.80 ± 0.10 | 9.29 ± 0.64 | 3.25 ± 0.26 | |
OSL/Rep/3/3 | GdTL-4591 | 110 | 15 | 27.0 ± 0.8 | 43.0 ± 0.9 | 333 ± 26 | 2.237 ± 0.085 | 239 ± 26 | 107 ± 12 | |
OSL/Rep/3/4 | GdTL-4592 | 30 | 8 | 14.5 ± 0.5 | 16.7 ± 0.5 | 129 ± 10 | 1.132 ± 0.044 | 201 ± 13 | 178 ± 70 | |
TG | OSL/TG-1 | GdTL-4675 | Corridor | 7 | 59.9 ± 5.8 | 43.8 ± 6.4 | 152 ± 28 | 2.23 ± 0.382 | 1.23 ± 0.01 | 0.55 ± 0.10 |
14.29 ± 0.55 | 0.23 ± 0.30 | 4.9 ± 2.8 |
OSL ages presented as years before 2023.
In the case of the dose rate for ceramic, the activity of the surrounding environment was taken into account.
For shafts REP/2 and REP/3, surface material was also collected for 137Cs and 210Pbex activity analysis.
As can be observed in the results, the vast majority of obtained radiocarbon dates fall within a similar range, covering the period of the 15th–17th centuries (see
The results of the research allowed for obtaining information on the age of remains from historical mining in the vicinity of Tarnowskie Góry. In the case of determination of the age using the AMS method, 12 results were obtained for 11 samples, and out of these obtained results, 9 fall within the range of 1435–1645 cal AD, while one age is younger than 1645 cal AD and covers a few age ranges. Two results are significantly older and cover the period of the beginnings of the Polish State. These results cannot be excluded, and it is possible that they refer to attempts of earlier exploitation in the tested area, even entering into the prehistoric period. However, this issue seems to be open and requires further detailed research. The results obtained with the OSL method are significantly overestimated due to poor or lack of bleaching. Future research should cover not only the organic part of the shafts but also the boundary between former ground level and waste rock, as it indicates when the shaft began to be used.