Investigating the Microarchaeological Record at Underwater Sites: Operating an On-Site Laboratory During the Antikythera Shipwreck Excavation

Journal of Maritime Archaeology https://doi.org/10.1007/s11457-024-09415-5 RESEARCH Investigating the Microarchaeological Record at Underwater Sites: Operating an On‑Site Laboratory During the Antikythera Shipwreck Excavation Isaac Ogloblin Ramirez1,2,3,4 · Angeliki Simosi5 · Lorenz Baumer6 · Orestes Manousos4 · Patrizia Birchler Emery6 · Timothy Pönitz6 · Alexandros Sotiriou4,6 Accepted: 20 August 2024 © The Author(s) 2024 Abstract Underwater excavations require an immense amount of logistics and have inherent time limitations. Underwater challenges such as nitrogen toxicity, underwater color change, and dive time limits increase with working depths, affecting the interpretation of archaeological contexts. Thus, underwater excavations involve methods and approaches to extract the maximum information from small areas while providing a comprehensive understanding of the archaeological record. Here, we present the benefits of using an on-site laboratory comprising a microscope, binocular microscope, Fourier transform infrared spectrometer and blue light inspection device. Three case studies are presented, focusing on the identification of stratigraphic boundaries, as well as the preservation and identification of archaeological materials. The results show a complex stratigraphic sequence containing seven layers divided into four mineralogical units: (1) Calcite, (2) Calcite and aragonite, (3) Aragonite, and (4) Dolomite. Additionally, the use of an on-site laboratory is effective in preventing the misidentification of archaeological materials, which could affect the final interpretation of the archaeological site (e.g., glass, lead, bone), and enabling the identification of materials invisible to the naked eye, such as opaline phytoliths. In the case of the Antikythera shipwreck, the on-site laboratory facilitated the examination of stratigraphy and quality of the archaeological context while streamlining excavation practices and documentation. Furthermore, the on-site laboratory allowed for the assessment of material preservation and provide crucial insights to inform post-excavation treatments and analysis of artifacts. Keywords Underwater archaeology · Nautical archaeology · Geoarchaeology · FTIR · Phytoliths Introduction Investigating macro and microscopic archaeological context is essential for obtaining a comprehensive understanding of archaeological sites. Large-scale features such as architectural elements, shipwreck remains, and a wide range of other artifacts or eco-facts, are Extended author information available on the last page of the article Vol.:(0123456789) Journal of Maritime Archaeology part of the macroarchaeological record. On the other hand, the microarcheological record reveals the archaeological remains that are not visible to the naked eye, such as anthropogenic micro-remains, ash pseudomorphs, phytoliths and dung spherulites (Cabanes 2020; Gur-Arieh and Shahack-Gross 2020), or changes in the molecular structure of artifacts (e.g., heated sediment, Berna et al. 2007). This invisible record can be traced within archaeological sites both on land and in marine environments (Ogloblin Ramirez et al. 2021; Shahack-Gross 2017). By integrating interpretation of macro and microfinds, a more holistic view of the archaeological site under study can be achieved. Complex anthropogenic and natural activities can be deciphered, including technological innovation, subsistence strategies, use of space, and long-term environmental impacts (Cereda et al. 2023; Edgeworth 2010; King et al. 1990; Shahack-Gross 2017; Shahack-Gross et al. 2005; Stein and Teltser 1989; Weiner 2010). Typically, macroarchaeological records are examined and documented in situ, and data acquisition is carried out to facilitate the microarcheological analysis and interpretation after completion of the fieldwork. However, on-site laboratories are becoming common in modern terrestrial archaeological excavations, providing immediate access to analytical tools and expediting the processing, analysis, and interpretation of microarcheological records (Frahm and Doonan 2013; Hodder 2017; Shahack-Gross 2017; Weiner 2010). As a result, a synergetic multidisciplinary team can pose new questions and interpretations on a day-to-day basis while still in the field. It has been shown that if analytical instrumentation and microarchaeological specialists are available on site, excavations can benefit from microarchaeological interpretations proposed while the fieldwork is in progress (Frahm and Doonan 2013; Hodder 2017; ShahackGross 2017; Weiner 2010, 261–262). We note multiple advantages of an on-site laboratory: (1) It allows for immediate integration of analysis results into the ongoing excavation, promoting a problem-solving approach that provides timely answers and refines research questions. By analyzing samples on site, research questions can be efficiently tested and adjusted, leading to a more effective selection of samples for off-site analysis. (2) Because excavation is a destructive process, the integration of real-time information helps adjust the excavation process according to the nature of the materials being exposed. By obtaining and analyzing samples interactively, the number of samples required for accurate mapping can be significantly reduced. (3) On-site laboratories are valuable for mapping feature boundaries, aiding in understanding site formation processes and stratigraphic complexities. (4) Collaboration between archaeologists who simultaneously interpret microscopic and macroscopic records enhances communication, team cohesion, and overall excavation quality. It should be noted that on-site laboratories are suitable only for a preselected set of analyses, restricted by available instrumentation and the specialty of the employed scientific personnel. In addition, their use comes at an increased operational cost comparable to that of dedicated analytical facilities in specialized research institutions. Nonetheless, the use of on-site laboratories is increasingly preferred in modern terrestrial archaeology (Frahm and Doonan 2013; Hodder 2017; Shahack-Gross 2017; Weiner 2010). On‑Site Instrumentation for Underwater Archaeology The application of on-site laboratory analysis in the field of underwater archaeology has been relatively limited thus far. While efforts have been made to develop instrumentation and techniques to enable in situ analysis, the use of on-site laboratories, similar to those Journal of Maritime Archaeology employed in terrestrial archaeology, has not been fully explored in the field of underwater archaeology. Previous methodological work has been performed to study underwater sediment profiles by analyzing in situ pH, sulfide, and redox potential (Gregory 2020). Furthermore, X-ray fluorescence (XRF) technology has been used for in situ analysis in marine archaeology and these instruments are capable of determining the elemental composition of various materi (...truncated)