Research Article, Geoinfor Geostat An Overview Vol: 13 Issue: 3

Establishing Deep Time: Multi-Method Dating of Archaeological and Speleological Features in the Bosnian Valley of the Pyramids

Sam Osmanagich^*

Principal Investigator, Archaeological Park, Bosnian Pyramid of the Sun Foundation, Visoko, Bosnia and Herzegovina

*Corresponding Author: Sam Osmanagich
Principal Investigator, Archaeological Park, Bosnian Pyramid of the Sun Foundation, Visoko, Bosnia and Herzegovina
E-mail: mantonikolaidi@gmail.com

Received date: 03 May, 2025, Manuscript No. GIGS-25-165105; Editor Assigned date: 06 May, 2024, PreQC No. GIGS-25-165105 (PQ); Reviewed date: 20 May, 2024, QC No. GIGS-25-165105; Revised date: 27 May, 2024, Manuscript No. GIGS-25-165105 (R); Published date: 03 June, 2024, DOI: 10.4172/2327-4581.1000437

Citation: Osmanagich S (2025) Establishing Deep Time: Multi-Method Dating of Archaeological and Speleological Features in the Bosnian Valley of the Pyramids. Geoinfor Geostat: An Overview 13:3.

Abstract

Keywords

Radiocarbon dating; Bosnian pyramids; Ravne tunnel complex; Speleothem chronology; Paleoarchaeology; Multimethod geochronology

Introduction

The Bosnian Valley of the Pyramids, located near the town of Visoko in central Bosnia-Herzegovina, has emerged over the past two decades as one of the most debated archaeological landscapes in Southeastern Europe. Since its identification as a site of interest in the early 2000s, the area has undergone continuous excavation and multidisciplinary study led by the Archaeological Park: Bosnian Pyramid of the Sun Foundation. The valley includes prominent geomorphological features such as the Bosnian Pyramid of the Sun, the Pyramid of the Moon, the Pyramid of the Dragon, and an extensive network of subterranean passages known as the Ravne Tunnels.

Despite initial skepticism regarding the anthropogenic nature of these formations, accumulating stratigraphic, architectural, and geophysical evidence has warranted closer scientific investigation. Notably, numerous megalithic terraces, aligned dry-stone walls, and artificially shaped concrete-like blocks have been unearthed at several depths and across multiple pyramid structures. In parallel, the Ravne tunnel systems have yielded dry-stone reinforcements, complex sediment layers, and speleothem formations which provide invaluable temporal markers.

To establish a scientifically grounded chronology for the valley’s development, the current research integrates multiple dating techniques. Radiocarbon (C-14) dating, Uranium-Thorium (U-Th) series analysis, and pedogenetic soil assessment have been applied to organic remains, speleothems, and stratified construction materials. These analyses aim to identify both minimum and possible construction dates and offer a framework for interpreting phases of human activity in the region.

This paper presents the results of these multi-method dating efforts and evaluates their implications within the broader context of Balkan prehistory and deep-time archaeology. Emphasis is placed on methodological transparency, cross-validation of results, and careful consideration of post-depositional processes that may affect dating accuracy. By doing so, the study contributes to a more nuanced understanding of long-term human-environment interaction in one of Europe’s least explored prehistoric landscapes [1].

Materials and Methods

This study applies a multi-method chronological approach to key sites within the Bosnian Valley of the Pyramids, including the Bosnian Pyramids of the Sun and Moon, as well as the Ravne and Ravne 3 tunnel systems. Analytical material included organic remains (charcoal, wood, sediment-bound carbon), carbonate formations (stalagmites, calcite crusts), soil layers and structural elements recovered from systematic excavation campaigns spanning 2006 to 2025.

Excavation strategy and site selection

Excavation was conducted under the supervision of the Archaeological Park: Bosnian Pyramid of the Sun Foundation, with formal permits issued by the Cantonal Ministry of Culture (Zenica- Doboj Canton). A total of 20 trenches were opened on the Bosnian Pyramid of the Sun and 64 trenches on the Bosnian Pyramid of the Moon. Over 2.6 kilometers of tunnels were cleared in the Ravne and Ravne 3 underground complexes. Stratigraphic excavation, trench documentation, and material sampling were conducted according to standard archaeological protocols [2].

Radiocarbon (C-14) dating

Organic material including wood fragments, charcoal, and carbon-containing sediments was submitted for radiocarbon analysis to the following laboratories:

• Institute of Environmental Geochemistry, National Academy of Sciences, Kyiv (Ukraine)

• Beta Analytic Radiocarbon Dating Laboratory, Miami (USA)

• TÜBİTAK Marmara Research Center AMS Laboratory, Gebze (Turkey)

• Laboratory for Isotope Research, Silesian University of Technology, Gliwice (Poland)

• Angström Laboratory, Uppsala University (Sweden)

• Leibniz Laboratory for Radiometric Dating and Stable Isotope Research, Christian-Albrechts University, Kiel (Germany)

Samples underwent standard pre-treatment protocols including Acid-Base-Acid (ABA) processing or acid dissolution (for carbonates). AMS (Accelerator Mass Spectrometry) and liquid scintillation counting methods were used. Radiocarbon dates were calibrated using the IntCal13 or IntCal20 Northern Hemisphere calibration curves [3].

Uranium-Thorium (U-Th) series dating.

U-Th dating was applied to stalagmites and calcite crusts found in undisturbed sections of the Ravne 3 tunnel. Laboratory analysis was conducted as follows:

• Chemical separation of uranium and thorium was performed using TRU-resin chromatographic extraction at the Institute of Geological Sciences, Polish Academy of Sciences (Warsaw).

• Isotopic measurements were completed at the Institute of Geology, Czech Academy of Sciences (Prague), using a doublefocusing sector-field ICP-MS (Element 2, Thermo Finnigan) [4].

All results were corrected for blanks and isotopic fractionation using internal laboratory standards.

Soil pedogenesis and relative dating

Soil samples taken from sediment layers overlying structural elements (e.g., concrete blocks) were examined by the Federal Institute for Agropedology (Sarajevo). Chronological estimates were based on depth, humus concentration, and clay mineral content. These data provided a relative terminus ante quem for underlying features.

Documentation and visualization

Each sample context was documented with scaled photography, stratigraphic sketches, and GIS-based mapping. 3D terrain modeling and remote sensing data (including LiDAR and satellite-based elevation models) were integrated into the geomorphological analysis, particularly around the Bosnian Pyramid of the Moon and related alignments [5].

Results

Excavations conducted across 20 archaeological trenches on the Bosnian Pyramid of the Sun uncovered structural features consistent with artificial construction (Figure 1). Large, regularly shaped concrete-like blocks were found approximately 1 meter beneath the surface layer of soil and vegetation (Figure 2). These blocks were arranged in rows and exhibited uniform orientation and smooth surfaces, particularly in Trench 4C and at the uncovered northeastern corner (Figure 3).

Bosnian pyramid of the sun

Radiocarbon dating of organic material found between these concrete layers yielded significant chronological results. A sample submitted to the Kyiv radiocarbon laboratory (IHME-3734) produced an uncalibrated age of 29,200 ± 400 BP, which calibrates to approximately 33,800 years BP using the IntCal calibration curve. An earlier sample from Trench 20 dated to 24,800 ± 200 BP supports this Late Pleistocene construction estimate (Figure 4). These findings are consistent with earlier soil analyses performed by the Federal Institute for Agropedology in Sarajevo, which dated the overlying pedogenic soil to between 12,000 and 15,000 years BP, confirming that the structure beneath must be older (Figure 5). Complementary interpretations by Dr. Paul LaViolette and others have affirmed this chronology, projecting a calibrated construction window of approximately 33,800 BP [6].

Bosnian pyramid of the moon

The Bosnian Pyramid of the Moon was investigated through 64 archaeological trenches, which uncovered extensive sandstone terraces arranged in a stepped or cascading pattern from base to summit (Figure 6). Terraces were arranged along a north-south axis and often separated by thin layers of clay, possibly used for acoustic or thermal insulation (Figure 7).

In 2013, radiocarbon analysis was performed on carbon-rich material embedded within these terraces. Laboratory results from Kyiv and Uppsala yielded uncalibrated ages of 10,350 ± 50 BP and 6,450 ± 30 BP, respectively (Figure 8). These dates, though significantly younger than those from the Pyramid of the Sun, still suggest the site's prehistoric occupation.

Astronomical alignments associated with the Pyramid of the Moon further contextualize its importance. Observations indicate that during the summer solstice, the shadow of the Pyramid of the Sun completely envelopes the Pyramid of the Moon just before sunset, touching its summit (Figure 9). Additional astronomical shadow phenomena are observed during the equinoxes and winter solstice (Figures 10–12).

Ravne and ravne 3 tunnel complexes

Systematic clearing of over 2.6 kilometers of the Ravne tunnel network revealed more than 50 dry-stone walls, five side chambers, and several large ceramic megaliths (Figure 13). Radiocarbon dating of organic materials extracted from tunnel fill produced diverse results. Charcoal from near a dry-stone wall in Ravne 3 was dated by TÜBİTAK AMS Laboratory to 1677 ± 23 BP, corresponding to a calibrated range of 261–423 CE, indicating post-construction visitation during Late Antiquity (Figure 14) [8].

Earlier radiocarbon results from the Ravne tunnels provided more ancient dates:

• A wooden artifact embedded in conglomerate dated to 34,000 ± 1,500 BP by Silesian University (Gliwice)

• A second sample from the same object dated to 30,600 ± 525 BP by Leibniz Laboratory, Kiel (Tables 1 and 2)

Table 1: Radiocarbon Dating Analysis of Sample S001

Table 2: Radiocarbon Analysis of Samples from Tunnel Ravne 3: Laboratory Procedures and Results

These dates suggest a much earlier formation or reuse of the tunnels than previously considered. Stalagmites within Ravne 3 provided additional chronological insight. Radiocarbon dating of the S001 sample produced a wide range of ages, including a layer dated to 26,200 ± 250 BP (Figure 15). U-Th dating of nearby stalagmites (US001 and S008) produced ages of 19,000 ± 1,000 BP and 15,000 ± 1,000 BP, respectively, further corroborating the deep antiquity of tunnel formation (Tables 3 and 4).

Table 3: Sample submission and analysis information

Table 4: Charcoal radiocarbon dating from ravne 3 tunnel complex

Calcite crystal formations on the ceilings of the Ravne water section were also dated. A sample analyzed by Beta Analytic returned a calibrated age of approximately 7,430 years BP, indicating water infiltration and mineral deposition well before recorded history (Figure 16).

Summary of dating results

A synthesized chronology, presented in flowchart form (Diagram: Step-by-Step Dating of the Bosnian Pyramid of the Sun), integrates these multi-method dating results. The combined use of radiocarbon, U-Th, and soil profile analysis establishes a multi-phase chronology:

• Construction of the Bosnian Pyramid of the Sun: ~33,800 BP

• Primary activity in Ravne tunnel: ≥ 30,000 BP

• Use of the Pyramid of the Moon: 10,000–6,500 BP

• Post-construction human activity: ~4th century CE

Discussion

The results of this study contribute significantly to the growing body of interdisciplinary research on the Bosnian Valley of the Pyramids by establishing a layered and testable chronological framework. Through the combined application of radiocarbon and uranium-thorium dating, supported by soil profile analysis and stratigraphic observations, a compelling temporal sequence emerges that challenges conventional interpretations of the site's age and complexity [9].

Chronological implications for construction and use

The radiocarbon dates obtained from organic material embedded between concrete-like blocks on the Bosnian Pyramid of the Sun especially the calibrated age of ~33,800 BP suggest a construction phase that predates the Neolithic by tens of thousands of years. This places the pyramid well into the Late Upper Paleolithic, an era for which there is limited documentation of monumental construction on a global scale. The soil development analysis conducted by the Federal Institute for Agropedology supports this conclusion, dating the overlying soil to a minimum of 12,000–15,000 years old, thereby establishing a relative terminus ante quem for the pyramid’s surface features [10].

The Pyramid of the Moon, while younger in construction, reveals continuous use or modification across millennia, with radiocarbon dates clustering around 10,000–6,500 BP. The consistency of its terrace formations and their integration into astronomical alignments further support the interpretation of intentional design. Observations of solstitial and equinoctial shadow interactions between the Sun and Moon pyramids imply a high level of planning and astronomical knowledge.

Ravne tunnel system: Age, function, and reuse

The extensive network of Ravne and Ravne 3 tunnels presents a complex palimpsest of activity. The U-Th and radiocarbon dating of stalagmites, calcite deposits, and embedded wood indicate that many sections were open or accessible as early as 30,000–34,000 years BP. These results are bolstered by the presence of megalithic blocks beneath stratified conglomerate layers, suggesting tunnel formation prior to sediment infill and natural sealing. Notably, more recent human interaction with the tunnels is confirmed by charcoal samples dated to the 4th century CE, likely reflecting reuse or ritual visitation rather than original construction. This pattern of initial Paleolithic construction followed by millennia of silence and eventual rediscovery is consistent with other ancient megalithic sites globally [11].

Methodological reliability and interdisciplinary integrity

While early debates surrounding the Bosnian Pyramids focused heavily on their classification as natural or artificial, this study emphasizes the value of verifiable scientific methods to bypass that dichotomy. The chronological data presented herein are independently verifiable, laboratory-validated, and sourced from internationally accredited institutions. The potential presence of "dead carbon" in speleothems and sediment-bound samples was accounted for through methodological triangulation combining U-Th and C-14 dating with geochemical context to assess contamination risks. Calibration curves (IntCal13 and IntCal20) were consistently applied, and sample integrity was maintained through careful stratigraphic documentation and international submission protocols.

Context within southeastern European prehistory

The findings of this study suggest the Bosnian Valley of the Pyramids may represent one of the earliest examples of megalithic activity in Southeastern Europe, potentially predating known Mesolithic and Neolithic cultures in the region. While this interpretation remains provisional, pending further excavation and interdisciplinary review, the currently available evidence necessitates the reconsideration of cultural capacities in the Late Pleistocene Balkans [12].

Future research directions

The results presented in this study underscore the need for continued, multidisciplinary investigation of the Bosnian Valley of the Pyramids. The unexpectedly early radiometric dates, particularly those related to the Bosnian Pyramid of the Sun and the Ravne tunnel system, invite further scrutiny not only to refine current chronologies but also to explore the broader cultural and environmental implications of the findings.

Expanded radiometric sampling

Future work should prioritize broader radiocarbon and U-Th sampling across stratified contexts and a wider variety of materials. This includes:

• Additional dating of stalagmites and calcite crusts in the lessdisturbed sectors of Ravne 3;

• Targeted radiocarbon analysis of organic residues found beneath megalithic terraces on the Pyramid of the Moon;

• Testing of sedimentary carbonates within sealed segments of the Ravne tunnels, especially where construction-like dry walls intersect flowstone deposits.

Ensuring redundant testing across multiple laboratories will further strengthen chronological confidence and mitigate concerns over localized contamination.

Geoarchaeological correlation

Improved correlation between radiometric dates and geomorphological processes such as sediment transport, percolation pathways, and pedogenic changes will help differentiate between construction-related events and natural depositional sequences. Detailed soil micromorphology, isotope geochemistry, and mineral composition studies could offer further insights into anthropogenic versus natural layering [13].

Non-Invasive subsurface imaging

Geophysical techniques such as Ground-Penetrating Radar (GPR), Electrical Resistivity Tomography (ERT), and muon tomography should be deployed more extensively to detect potential internal structures within the pyramidal formations and to trace the full extent of subsurface voids or tunnel branches. Integration with existing LiDAR and photogrammetric models will aid in predictive excavation planning.

Cultural and astronomical integration

As astronomical alignments continue to emerge as a significant architectural feature, systematic archaeoastronomical surveys— including simulations of celestial movements in prehistoric epochs should be undertaken. Ethnographic analogs and regional mythohistorical records may also yield context for intentional site orientation and landscape symbolism.

Open Data and Peer Collaboration

To facilitate broader academic engagement, future research should prioritize transparent, peer-accessible publication of datasets, including all laboratory reports, field logs, and calibration files. The promotion of open scientific dialogue across disciplines— archaeology, geology, physics, and archaeoastronomy is essential to assess the site's significance with both rigor and neutrality [14].

Conclusion

The Bosnian Valley of the Pyramids presents a unique and complex archaeological landscape whose features warrant serious scientific attention. Through the application of radiocarbon dating, uranium-thorium series analysis, and soil chronology, this study provides a coherent multi-method framework for establishing the temporal depth of key structures within the valley—including the Bosnian Pyramids of the Sun and Moon and the Ravne tunnel systems.

The evidence consistently points toward phases of construction or accessibility that significantly predate the Neolithic period, with calibrated radiocarbon dates as early as 33,800 years BP for the Pyramid of the Sun and 30,600–34,000 years BP for embedded organic material in the Ravne tunnels. Meanwhile, the Pyramid of the Moon demonstrates layered human interaction over thousands of years, supported by its integration into astronomical alignments and extensive megalithic terraces. The discovery of Late Antiquity charcoal within Ravne 3 indicates later, secondary human engagement with the site, reaffirming its long-term cultural relevance.

These findings challenge prevailing assumptions about prehistoric activity in the Balkans and highlight the need for continued, transparent, and interdisciplinary research. While questions remain regarding the origin, function, and cultural context of these structures, the robust chronological data establish a factual baseline from which further archaeological, geological, and archaeoastronomical inquiry can proceed.

Acknowledgment

The author expresses sincere gratitude to the Federal Institute for Agropedology (Sarajevo) and its late director Prof. Husnija Resulovi�? for foundational research on pedogenetic soil dating on the Bosnian Pyramid of the Sun. The author also acknowledges the editor of the ICBP Proceedings, the late Professor Muris Osmanagi�?, for his early support in promoting interdisciplinary scientific dialogue related to the Bosnian Valley of the Pyramids.

Special thanks are extended to the following laboratories for conducting radiocarbon and uranium-thorium dating with methodological precision and professionalism:

• Silesian University of Technology, Gliwice, Poland

• Leibniz Laboratory for Radiometric Dating, Kiel, Germany

• Uppsala University, Sweden

• TÜBİTAK MRC AMS Laboratory, Turkey

• Beta Analytic Radiocarbon Dating Laboratory, USA

• Institute of Geological Sciences, Polish Academy of Sciences, Warsaw

• Institute of Geology, Czech Academy of Sciences, Prague

The author further acknowledges the contributions of professional archaeologists who led and supervised field excavations during various seasons: Ricardo Brett, Nicolo Bisconti, and Sarra Acconci (Italy); Tim Moon (New Zealand); and Andrew Lawler (United Kingdom), whose detailed trench documentation and stratigraphic interpretation strengthened the archaeological integrity of the site.

Appreciation is also extended to the Cantonal Ministry of Culture (Zenica-Doboj Canton) for its continued support in authorizing excavation permits and facilitating long-term heritage preservation.

Finally, the author expresses heartfelt thanks to the local community of Visoko and the thousands of international volunteers who have contributed their time, energy, and goodwill to this ongoing research effort since 2005.

Funding statement

This research was independently funded by the author, Dr. Sam Osmanagich, and conducted under the auspices of the Archaeological Park: Bosnian Pyramid of the Sun Foundation. No external grants were received for the design, data collection, analysis, or publication of this study.

Competing interests

The author declares no competing financial or non-financial interests relevant to the content of this article.

Author contributions

Dr. Sam Osmanagich was solely responsible for the conception, fieldwork coordination, sample collection, literature review, data interpretation, manuscript writing, and submission process.

Ethics approval and permissions

All archaeological investigations were conducted with formal approval from the Cantonal Ministry of Culture (Zenica-Doboj Canton) and were carried out in compliance with local cultural heritage protection laws. No human or animal subjects were involved in this study.

Data availability

All laboratory reports, dating certificates, and field documentation cited in this study are available from the corresponding author upon reasonable request. Select documents are publicly accessible via the Foundation's official archive (http://www.piramidasunca.ba, www.icbp.ba) and booksbydrsam.com.

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