Ongoing archaeometric research on ancient and modern shipwrecks at the University of Cadiz

Felipe Cerezo
Underwater and Nautical Archaeology, School of Philosophy and Letters, University of Cadiz, Spain. felipe.cerezo@uca.es 

Nicolás C. Ciarlo
National Scientific and Technical Research Council (CONICET) - Institute of Archaeology, School of Philosophy and Letters, University of Buenos Aires, Argentina. nciarlo@conicet.gov.ar 
Manuel Bethencourt
Department of Materials Science, Metallurgy Engineering and Inorganic Chemistry, International Campus of Excellence of the Sea, University of Cadiz, Spain. manuel.bethencourt@uca.es


Since 2016, the International Doctoral School in Sea Studies at the University of Cadiz (EIDEMAR-UCA), Spain, has offered two degree programs: a MA Program in Nautical and Underwater Archaeology, and a PhD Program in Maritime History and Archaeology. Several European and Latin-American students have conducted archaeometric research within this scenario. Thus far, studies cover a wide range of archaeological remains from ancient and modern shipwrecks, chiefly located in Andalusian waters. Strong collaboration with other national and international institutions allowed deepening into subjects of both local and regional interest.

Preliminary results of these initiatives have resulted in several MA theses (a complete list is available at: https://eidemar.uca.es/informacion-publica-disponible-master-en-arqueologia-nautica-y-subacuatica/tfm-defendidos/). They also settled the ground for the development of PhD projects, which are currently in course. A brief account on a selection of these works is presented below.

Several Roman period artifacts carried on board as cargo and as part of the equipment have been studied in Cadiz. Among them, lead anchor stocks located in the Archaeological Museum of Cadiz and scattered at the Algeciras bay, and a cargo of copper ingots from a 1st century AD shipwreck located near the Sancti Petri Island (named Arapal, after his finders), are worth mentioning. A sample of stocks were selected for a PhD study, which combines epigraphic information and compositional data obtained by analytical means for dating and assess its provenance, and to examine the deterioration process to which they were subjected in different underwater conditions (E. Fernández, M. Bethencourt, and L.C. Zambrano). On the other hand, the Arapal site has one of the most important cargoes of this kind studied so far (Figure 1). A first approach to this collection, which included LM, SEM-EDS, DRX, FRX, IPC-MS, and OES of an ingot, has been recently performed (R. Morón). Furthermore, a current PhD research seek to understand the main characteristics and quality of casting technology used at this period, as well as the production centers and trade networks, using archaeometric data and epigraphic information (L. Matas, M. Bethencourt, and F. Cerezo).

Figure 1. Cargo of copper ingots recorded and recovered during fieldwork activities at the Arapal site (2017): (a) partial view of the cargo, located in situ; (b) ingot no.64; and (c) sample selected for SEM-EDS analysis (Photos courtesy of University of Cadiz).


Other themes developed as part of the MA theses focused on evidence from ancient shipwrecks included provenance analysis of the amphorae cargo of the Cap Béar 3 site, Port-Vendres, France, dated from 50 to 40 BC (I. Sánchez); metallurgical characterization and degradation process diagnosis of a lead anchor stock from the Roman period (E. Fernández); and controlled experimentation with silicone materials to improve the underwater molding methods used for recovering fragile remains (S. de León).

On regards as modern times, from 2017 to 2019 a team lead by F. Cerezo and R. Gallero revisited a late 16th to early 17th century shipwreck located in Algeciras, known as La Ballenera. From recent excavations, conducted with the assistance of MA students, a large quantity of Italian marmorizatta pottery pieces was recovered, among other remains. This collection has been recently subject to analysis, and compared with archaeological samples from workshops of Tuscany, aiming to circumscribe its provenance (L. Pérez). Several metal artifacts related to ammunition and a gunner’s instrument for stone and ferrous shot were also found, and they are currently under examination.

A joint effort between specialists from the Centre of Underwater Archaeology of the Andalusian Historical Heritage Institute (J. Martí), the University of Cadiz (M. Bethencourt and S. López), and the National Scientific and Technical Research Council of Argentina (N.C. Ciarlo), can also be highlighted. It is focused on the study of scrap bronze cannons (for melt and recast) recovered from the cargo of a mid- to late 17th century Dutch merchant ship, which sank in the Cadiz port. Metallurgical analyses are conducting to assess the alloys quality and manufacturing process and to discuss the conditioning factors involved in the manufacture of these defective pieces.

More recently, metal fastenings and sheathing used to protect wooden ships’ hulls from late 18th to mid-19th century is also under examination to determine its composition and production. Data on copper and copper-based samples recovered from shipwrecks located in Mexican waters is contributing to discuss decisions on design and construction of vessels used for the Atlantic sailing, as well as to assess the transfer of technology from Spain to its oversea territories, in particular to Nueva España (D. Arano, M. Bethencourt, G. Carrasco, and N.C. Ciarlo).

Last but not least, the project ‘Perspectives of in situ preservation of Underwater Cultural Heritage. Risk indices and impact of climate change (ARQUEOCHANGE)’, is a recent initiative proposed by M. Bethencourt and T. Fernández. Based on the successful experience of ARQUEOMONITOR (http://www3.uca.es/serv/geoportal/), this work stresses the effects of marine environmental conditions and climate change on underwater archaeological remains. The main goal is to design a model to identify cultural heritage at risk, at a local and regional level, that help to apply adequate measurements for its safeguarding. In time, it will aid to create at the Campus of International Excellence of the Sea (CEIMAR) a collaborative net between different institutions and professionals from Spain and abroad, dedicated to the study and conservation of Underwater Cultural Heritage by combining different perspectives and archaeometric techniques.

In sum, activities conducted within the laboratories of the University of Cadiz have contributed to the academic formation of degree students and to develop a line of archaeometric research with focus on remains from shipwrecks. Encouraging both the academic continuity of students, from the MA to the PhD program, and the collaboration between specialists and institutions, seems to be a fruitful path to further exploit the potential of these exciting studies.

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