Site-specific applications
Although regional geoarchaeological investigations are of primary importance in archaeology, a fundamental premise of the geoarchaeological endeavor, as originally formulated by Renfrew (1976), is to understand how a site is formed –in other words, to understand the context of the archaeological finds. Archaeologists who conduct excavations are well aware that the only means to reveal the context of the artefacts and features that they excavate is by studying the sediments and stratigraphy of the site (Goldberg and Macphail 2006). The geoarchaeology at the site-scale is concerned with the deposits of the site and with what people have left behind. It is thus focused on the formation processes that built the site and actually deals with archaeological sediments per se. The infinitive repertoire of anthropogenic settlement activities demands a special range of expertise. Fine-scale geogenic sedimentary processes such as rain-, sheet-wash or ponding, and human-induced post-depositional alterations and disturbances such as trampling, dumping, digging and backfilling usually fall outside the ‘background knowledge’ of geoarchaeologists working in large-scale projects. Therefore, it is not a surprise that this side of geoarchaeology is comparatively underexplored, even though its importance is being ever more appreciated in recent times.
Nevertheless, studies in ‘microarchaeology’ (sensu Weiner 2010) have been conducted at a number of Greek sites already from the very beginnings of geoarchaeological applications. One of the first works was that of Davidson (1973), who applied grain-size and phosphate analyses in the Neolithic tell of Sitagroi, northeastern Greece. Particle size was used to locate the source of the tell material, which was found to be the local alluvium that was used for the construction of houses. Moreover, phosphate analysis was employed to define occupational intensities and abandonment phases. With his work on the processes of tell-formation and erosion in the plain of Drama in northern Greece (Davidson 1976), the same researcher contributed to the first edited volume of geoarchaeology (Davidson and Shackley 1976). Davidson and his co-workers recently continued their research on Greek tells, showing how a multi-element analysis of on-site deposits can identify the geochemical distinctiveness of several archaeological contexts (pit, house, plaster floor, alley, road and yard) (Davidson et al. 2010).
Most of the early on-site geoarchaeological investigations in Greece, however, were conducted in the course of projects targeting Palaeolithic caves, such as those of Kastritsa, Asprochaliko and Kalamakia (Higss and Vita-Finzi 1966; Bailey et al. 1983; De Lumley and Darlas 1994). Later on, in line with the golden period of the regional geoarchaeological studies associated with the Franchthi project, William Farrand studied the stratigraphy and the sediments of Franchthi Cave. His complete work was published in an individual volume (Farrand 2000), but results from the same study were also published separately and often in comparison with other cave studies (Farrand 1987, 1988, 2001 and 2003). One of the main contributions of Farrand’s work in the study of Franchthi Cave was the recognition and interpretation of hiatuses in the cave sequence on the basis of stratigraphic criteria and a set of sedimentary laboratory examinations. The laboratory analysis included particle size, pebble morphology, roundness and porosity, CaCO3 content, organic matter and pH measurements. Another important finding was the identification of a volcanic tephra layer at the base of the sequence attributed to the well-known Campanian Ignimbrite eruption at ca. 40 ka (Vitialiano et al. 1981), which was recently re-analyzed by Lowe et al. (2012). The same tephra was identified at another nearby Palaeolithic cave, Klissoura Cave I; combined with research at other sites from the eastern Mediterranean, tephrostratigraphy enabled the synchronization of archaeological and paleoclimatic records and thus provided important insights into the Middle to Upper Palaeolithic transition and the co-occurrence of Neanderthals with anatomically modern humans in Europe (Lowe et al. 2012).
The same array of sedimentary laboratory methods was also used in another major on-site geoarchaeological project in the Upper Palaeolithic rockshelter site of Klithi, Epirus (Bailey and Woodward 1997; Woodward 1997a). Likewise in the case of the Franchthi Cave, in this study it was shown clearly that the size and form of the coarse limestone particles found in Mediterranean caves and rockshelters are conditioned more by tectonic preparation of the host rock than by the influence of exogenic detachment mechanisms such as cryoclastism (Woodward and Goldberg 2001; Bailey and Woodward 1997; Woodward 1997a; Farrand 2000). In addition, it was shown that an understanding of fine sediment sources and related off-site processes is important for the reconstruction of site formation (Bailey and Woodward 1997). In the same line, Woodward et al. (2001) proposed a new approach in the quantitative estimation of the contribution of potential source materials in rockshelter sediment records. This approach employs a composite sediment fingerprinting method, which includes trace element analysis and magnetic susceptibility measurements complemented by micromorphological examination of the sediments.
At the same time, the above-mentioned studies revealed also the limitations of the traditional approaches in sedimentological analysis. Bailey and Woodward (1997) admitted that the sediment record in Klithi revealed a striking variability and complexity in the formation of the deposits, which resulted in a loss of resolution. Given this site-specific complexity that cannot be adequately scrutinized with field observations and conventional sedimentological analysis, the best alternative is to apply a microtextual approach based on microstratigrapy and microfacies analysis. Using these microscopic techniques it is possible to detect specific past human activities, identify the use of space and understand the depositional context of all archaeological remains. In particular, such an approach involves the application of micromorphology, namely the study on intact sediments and soils at a microscopic scale (Courty et al. 1989), as well as microchemical or physicochemical analyses of the same micromorphological samples by use of instrumental techniques (Mentzer and Quade 2013). The first attempts to apply micromorphological analysis in Greek archaeological sites are those carried out by Jamie Woodward (1997b) in Megalakkos rockshelter, Epirus and by Paul Goldberg in the sanctuaries of Demeter and Koros in Korinth (Bookidis et al. 1999). Both studies, however, were focused on specific archaeological features and were not meant to assess the entire array of formation processes of the sites. The study of soil erosion, agricultural terracing and site formation processes in the Early Bronze Age site of Markiani (Amorgos Island, Aegean Sea) is among the first systematic applications of micromorphology in Greece, albeit in a more regional context (French and Whitelaw 1999). That being said, it was not until the geoarchaeological investigations carried out in Theopetra Cave that micromorphology actually started to be conclusively applied in the study of site formation processes in Greece (Karkanas 1999, 2001).
The micromorphological study of the cave sediments at Theopetra revealed a very intriguing paleoenvironmental data-set. Repeated freeze/thaw activity during cold periods of the Late Glacial produced platy and spherical microstructures, which are the result of seasonal freezing temperatures well below 0°C (Figure 3a). Impressive and thick anthropogenic remains in the form of superimposed ash layers were found only in-between the cryogenically altered sediments. On the basis of the new series of thermoluminescence dates produced on burnt chert artefacts, it appears that the site was occupied only during warm climatic periods of the Upper Pleistocene (Valladas et al. 2007). In addition to the aforementioned assessments, the case of the Theopetra Cave exemplifies how powerful micromorphology can be, also as a tool in resolving problems related to post-depositional alterations. Elemental analysis performed on the micromorphological thin sections facilitated the identification of certain chemical alteration patterns and allowed for the reconstruction of the chemical palaeoenvironment prevailing at the site. In turn, these findings were used to determine whether the primary fossil and anthropogenic remains (bone, teeth, ash, phytoliths, organic matter, etc.) had been affected by chemical alteration and, by extent, to indicate their past presence or absence (Karkanas et al. 1999, 2000).
Figure 3. Photomicrographs in plane polarized light of selective micromorphological samples from Greek archaeological sites.
a) Lenticular microstructure due to repeated freeze-thaw activity. Middle Palaeolithic, Theopetra Cave, Thessaly. b) Hearth construction made of red clay-rich sediment overlain by loose reworked burnt remains. The burnt remains consist of a chaotic mixture of grey calcitic wood ash, black charcoal and clay fragments detached from below. Upper Palaeolithic, Klissoura Cave I, Argolis. c) Half-burnt ovicaprine dung fragment inside burnt remains. Grey wood ash crystals are visible. Neolithic, Kouveleiki Cave A, Lakonia. d) Superimposed constructed floors made of different mixtures of lime and occupational debris. Fine black particles are microcharcoal. The red clay-rich layers represent finishing coats of the floors. Neolithic, Makri, Thrace.
Further micromorphological investigations in the Palaeolithic sites of Klissoura Cave I and Lakonis Cave provided detailed insights on site formation processes, specific burning activities and the use of space (Figure 3b), such as in situ burning and dumping areas, thereby enhancing our understanding of human behavior in the Palaeolithic (Panagopoulou et al. 2002-2004; Karkanas 2001; Karkanas 2010). In the Aurignacian layers of Kleisoura Cave I dated to 32-34 ka BP, several basin-like clay lined structures were examined with micromorphological, thermoanalytical and spectrophotometric techniques. Among other things, it was found that the clay structures were heated to temperatures between 400 to 600°C and, therefore, it was suggested that they were used as hearth structures for cooking purposes (Karkanas et al. 2004). Consequently, the analysis of combustion features demonstrated advanced human skills related to pyrotechnology and provided new information on the social life of humans in the beginning of the Upper Palaeolithic period.
One of the best examples of ‘site geoarchaeology’ is the study of stabling activities in caves of southern Europe. Micromorphological studies in Kouveleiki Caves A and B, Laconia, revealed specific human practices during the Neolithic, such as dung burning for clearing purposes and construction of mud floors (Figure 3c). The Kouveleiki case presents coherent evidence of a small-scale, self-contained and mixed farming household in a marginal area (Karkanas 2006). In another Neolithic cave in Poros, Cephalonia Island, lime plaster floors were identified, offering important insights into domestic activities during the Neolithic period (Karkanas and Stratouli 2008).
In Dispilio, a lakeside settlement by the Orestias Lake (Kastoria, northern Greece), microfacies analysis of the sediments, supported by a suite of environmental indices, has provided detailed palaeoenvironmental data and elucidated the main processes involved in the formation of the site throughout its history of occupation from the Middle Neolithic to Chalcolithic Period (Karkanas et al. 2011). The microfacies approach indicated a complex occupational pattern as the result of the interaction of fluctuating lake levels and the variable input of anthropogenic sediments at the site.
More recent micromorphological studies of occupational sequences in sites with architectural remains like Mycenae (Peloponnese) and Palamari (Skyros Island) reveal valuable information on the structure and history of the sites (Karkanas 2013a and b). In the Neolithic tell-site of Makri in northern Greece, different types of floors were identified (Figure 3d), implying specific maintenance practices and activities related to social behavior and organization (Karkanas and Efstratiou, 2009), whereas in the Bronze Age site of Mitrou, changes in floor maintenance practices are associated with cultural and social developments (Van de Moortel and Karkanas 2013). Micromorphology has even provided details about the process of backfilling and re-opening of the corridors of Mycenaean chamber tombs and the location, number, and slope of these re-openings. Constructed floors were also identified in the corridors and chambers of the tombs, allowing for the reconstruction of complex histories of mortuary practices and their social meanings (Karkanas et al., 2012). All of these recent studies bring a new dimension in the archaeology of urban sites and the investigation of sites with architectural remains, demonstrating that sediments, be that geogenic or anthropogenic, are of fundamental importance for the unraveling of past human behavior and the development of testable archaeological hypotheses.
A different on-site geoarchaeological approach in the examination of site formation processes is provided by the study of micro-artefacts in combination with particle-size analysis and novel computation methods (Kontogiorgos and Leontitsis 2005; Kontogiorgos et al. 2007; Kontogiorgos 2008, 2010). Micro-artefacts (i.e. cultural remains smaller than 2 mm in dimension such as micro-shell, micro-bone, micro-fragments of charcoal, etc.) constitute a significant part of a site’s cultural component and carry the potential of providing significant information on the use of space. The application of this methodology in the Neolithic sites of Paliambela and Korinos in central Macedonia enabled researchers to show the differences in the spatial organization of activities carried out at the sites (Kontogiorgos 2008, 2010).
Today, several important sites like Lykaion in Arcadia, Avgi in western Macedonia, Paliambela in central Macedonia, Koutroulou Magoula and Imvrou Pigadi in Thessaly and Sissi in Crete are the focus of ongoing micromorphological investigations with very promising results, conducted by a new generation of geoarchaeologists (Mentzer 2009; Roussos 2010; Karpentier 2011; Koromila 2012; Kyrillidou 2012).