Sourcing in archaeology is a term which refers to a wide range of efforts conducted by scholars in order to identify where a particular raw material resource occurs naturally. When possible, humans select living sites where available resources are abundant: resources such as plants and animals for food, wood for building houses and fires, stone for making tools and buildings, clay for making pottery, and all kinds of materials that make living possible.
However, not all materials used by people in the past were readily available to them: some materials had to be obtained from quite long distances away. Archaeologists call these long-distance resources 'exotic' or 'non-local'. For example, Baltic amber was an exotic material prized throughout Europe: but it was only available from certain quarries, and then traded cross-country to the final user.
Material Sourcing And Elites
Identifying where the raw material for an artifact or food came from is the first step. Identifying how the raw material reached the end user is also part of the equation, because it provides information concerning trade networks, and gives a proxy for relative "expense" of a particular good. If, for example, a particular raw material involves some special effort to retrieve it, by the time it gets to the settlement where it will be used, it may also be rare. A combination of "rare" and "difficult to obtain" as characteristics by definition make raw material expensive, and access to such a material may be limited to those who can pay for the retrieval: in other words, the elite members of a society. Thus, the presence of an exotic artifact within a particular residence can be used as one several pieces of evidence indicating elite status.
Exotic materials made it to users through long-distance trade, or through someone's own quarrying or gathering activities. Sourcing, finding out where the raw material of an exotic material came from, tells us how far people traveled to obtain that resource, or alternatively, how far a given material was transported through trade.
Not all sourcing identifies elite behaviors. For example, identifying the natural habitat of the house mouse on the Bronze Age Uluburun shipwreck helped scholars pinpoint the possible site of origin for the ship.
Common Sourcing Techniques
The most commonly material in archaeological studies subjected to sourcing is lithic (stone) artifacts, in which the geochemical makeup of different types of stone, particularly obsidian, is compared to that of known quarry sites. Techniques of identifying the trace elements which make up a particular source of lithic material include geochemical analysis, X-ray fluorescence (often abbreviated XRF) and instrumental neutron activation analysis (INAA).
Sourcing for plant and animal materials is often accomplished by comparing the native habitats for the material and identifying the locations where they grow. In other words, if seeds of particular plant are identified at a site far outside of its native growing range, that plan could be considered evidence of an extensive trade network, or the activities of an elite person or group within a society.
More recently, stable isotope analysis has been used to source all kinds of materials, include people themselves.
Some Recent Sourcing Studies
Argote-Espino D, Solé J, López-García P, and Sterpone O. 2012. Obsidian Subsource Identification in the Sierra de Pachuca and Otumba Volcanic Regions, Central Mexico, by ICP-MS and DBSCAN Statistical Analysis. Geoarchaeology 27(1):48-62.
Arnold DE, Neff H, Glascock MD, and Speakman RJ. 2007. Sourcing the Palygorskite Used in Maya Blue: A Pilot Study Comparing the Results of INAA and LA-ICP-MS. Latin American Antiquity 18(1):44–58.
Binder D, Gratuze B, Mouralis D, and Balkan-Atli N. 2011. New investigations of the Göllüdag obsidian lava flows system: a multi-disciplinary approach. Journal of Archaeological Science 38(12):3174-3184.
Chia S, Yondri L, and Simantunjak T. 2011. Obsidian sourcing in Bandung, Indonesia. Asian Perspectives 49(1):148-156.
Church MJ, Peters C, and Batt CM. 2007. Sourcing Fire Ash on Archaeological Sites in the Western and Northern Isles of Scotland, Using Mineral Magnetism. Geoarchaeology 22(7):747–774.
Cucchi T. 2008. Uluburun shipwreck stowaway house mouse: molar shape analysis and indirect clues about the vessel’s last journey. Journal of Archaeological Science 35(11):2953-2959.
Jiao T, Guo Z, Sun G, Zhang M, and Li X. 2011. Sourcing the interaction networks in Neolithic coastal China: a geochemical study of the Tianluoshan stone adzes.
Journal of Archaeological Science 38(6):1360-1370.Lubell D, Jackes M, Sheppard P, and Rowley-Conwy P. 2007. The Mesolithic-Neolithic in the Alentejo: archaeological investigations, 1984-1986. From the Mediterranean basin to the Portuguese Atlantic shore: Papers in honor of Anthony Marks Actas do IV congresso de arqueologia peninsular: Universidade do Algarve.
Luglie C, Le Bourdonnec F-X, Poupeau G, Atzeni E, Dubernet S, Moretto P, and Serani L. 2006. Early Neolithic obsidians in Sardinia (Western Mediterranean): the Su Carroppu case. Journal of Archaeological Science 34(3):428-439.
Wendt CJ, and Lu S-T. 2006. Sourcing archaeological bitumen in the Olmec region. Journal of Archaeological Science 33(1):89-97.
