Classification of North African fabrics by clay source

The kinds of clays and other sediments locally available in Cyrenaica provide a framework for broad but fundamental classification of North African fabrics in general. This was initially based on clay sources in their environs of ancient Greek Euesperides, for production of late Archaic to early Hellenistic pottery (c. 530–250 BC; Swift Reference Swift2005), and its successor Berenice for production of late Republican and Roman pottery (with contexts from the late second century BC onwards; Lloyd Reference Lloyd1977; Riley Reference Riley and Lloyd1979). Characterisation of the petrological groups is based on consistent features seen across a corpus of thousands of pieces from the Society for Libyan Studies’ excavation at Euesperides (Swift Reference Swift2005; Swift in Wilson et al. Reference Wilson, Bennett, Buzaian, Buttrey, Fell, Found, Göransson, Guinness, Hardy, Harris, Helm, Kattenberg, Morley, Swift, Wootton and Zimi2003; Reference Wilson, Bennett, Buzaian, Fell, Found, Göransson, Guinness, Hardy, Harris, Helm, Kattenberg, Tébar Megías, Morley, Murphy, Swift, Twyman, Wootton and Zimi2004; Reference Wilson, Bennett, Buzaian, Buttrey, Fell, Found, Göransson, Guinness, Kattenberg, Morley, Swift, Wootton and Zimi2005), combined with first-hand observations at other sites in Cyrenaica and Tripolitania.

Most Cyrenaican fabrics fit squarely within the classificatory scheme presented here (Table 1), but there are always outliers and atypical pieces to be found, probably the result of very localised variations in sediments, experimentation with textures and non-plastic inclusions by ancient potters, or the occasional import produced in superficially similar fabrics.

Table 1 Clay types, their fabrics, sources and attested locations

North African terra rossa fabrics

Like much of the North African littoral, Cyrenaica is covered extensively by terra rossa soils. Pedogenic, these thin soils are formed in situ above the limestone bedrock. Well drained, the lower levels accumulate iron oxides from the organic surface layers, resulting in the characteristic reddish colour which gives them their name.

North African terra rossa soils are rich in quartz grains, aeolian material transported by desert winds (ghibli) from the arid regions to the south. The quartz is often well rounded and highly spherical as a result of having been saltated along on the desert surface. Petrographically, the microstructure of these fabrics contains abundant grains of quartz fine enough to be considered as part of the matrix, giving these fabrics their hardness and finely granular texture (Figure 1). They frequently contain calcareous precipitates and limestone fragments from the chemical weathering of the limestone. These often degrade during firing leaving rounded voids, often with whitish carbonate halos (Figure 2).

Figure 1. Example of a terra rossa fabric from Euesperides showing a finely granular consistency and typical carbonate inclusions. Scale 10 mm. (Photo: K. Swift)

Figure 2. Petrographic thin section, PPL, showing abundant quartz grains and a spherical void with carbonate halo. Width of field approximately 0.5 mm. (Photo: K. Swift)

First-hand testing demonstrated that the clay component in Cyrenaican terra rossa soils separates easily from the larger silt-size fractions when elutriated. In soil samples, the clay component usually makes up around one quarter to one third of the volume. The granulometry of the levigated clays compares well to that of terra rossa fabrics, containing abundant fine quartz grains as well as fine carbonate precipitates in dried clay samples extracted from the soils. This dry clay powder would have been well suited as a coarsening material added to other kinds of clay (see ‘Admixture of clays and sediments’ below). Since the clays must be extracted from the terra rossa soils, their production would have involved the widespread and intensive use of elutriation, although naturally refined clays may have been sought out very locally, such as in gullies or field run-offs.

These fabrics are ubiquitous in Cyrenaica and were the most common fabrics in the coarse pottery assemblages from Euesperides, accounting for about half of all local wares with examples encompassing the entire range of major shapes in coarse pottery (Swift Reference Swift2005).

Punic terra rossa fabrics

Punic North African coarse ware imports to Euesperides were identified via similarities with the fabrics of Punic transport amphoras and with fabrics ubiquitous in surface scatters at Sabratha and Lepcis Magna. The Punic coarse pottery excavated at Euesperides provides direct evidence for trading networks extending across the Gulf of Syrte and more intense material-cultural interactions between Punic North Africa and Greek Cyrenaica than had hitherto been recognised (Swift Reference Swift2005). Although produced from similar sediments, Punic fabrics show subtle yet consistent differences in texture, hardness and granulometry which permit identification and differentiation from terra rossa fabrics from western Cyrenaica. Further, although Punic coarse pottery shapes of the fourth and third centuries BC followed basic Greek types, they show clear technological differences from the local wares produced at Euesperides. They are consistently much harder, suggesting some variation in pyrotechnologies between Punic North Africa and Greek Cyrenaica. There are also differences in forming techniques, including tooling, trimming and surface wiping, which suggests distinct ceramic production traditions. Interpreted technologically, such apparently minor differences in vessel micromorphologies in fact provide a crucial means of regional differentiation, particularly where fabrics are granulometrically similar.

Cyrenaican and Punic coarse wares suggest the differentiation of regional productions in quartz-limestone fabrics produced from terra rossa soils. A perennial problem in the study of archaeological pottery from North Africa, comparisons of Greek and Punic pottery from Euesperides show that apparently homogenous fabrics can be differentiated through a combination of petrological and technological studies. Such an approach also holds promise for the further differentiation of terra rossa fabrics within Cyrenaica and across the North African littoral. But the study of coarse pottery from Euesperides also suggests that this is only really feasible for substantial assemblages, since it relies on the recognition of consistent differences across large numbers of typologically similar pieces in the relatively restricted and standardised Greek repertoire of common shapes.

Cyrenaican marl clay fabrics

Extremely fine-grained and often powder, these calcareous clays typically fire to a light yellowish colour when oxidised and to greenish or grey colours in reducing kiln atmospheres. In Cyrenaica, seams of marl clays – argillaceous marine sediments laid down at the outflow of geologically ancient deltas – are found within the lithostratigraphic units of limestone which extend from Derna in the east almost as far as Benghazi in the west, and which form the Jebel Akhdar. The clays often contain microfossil inclusions characteristic of their sedimentary origin. In the fabrics local to Euesperides and Berenice these microfossils consist entirely of Heterostegina foraminifera (Figures 3 and 4). This is a result of narrow environmental parameters in the formation of the marine clay deposits, a promising and important means of differentiating them from marl clays and lithostratigraphic units elsewhere in Cyrenaica. For example, a wider range of other species of Nummulitidae (Figure 5) along with pecten bivalves are common in fabrics from Cyrene.

Figure 3. Marl clay fabric from Euesperides showing Heterostegina microfossil inclusions. Scale 10 mm. (Photo: K. Swift)

Figure 4. Petrographic thin section, PPL, of marl clay fabric from Euesperides showing abundant microfossil inclusions. Width of field approximately 2 mm. (Photo: K. Swift)

Figure 5. Marl clay tile fabric from Cyrene showing inclusions of Nummulitidae foraminifera. Scale 10 mm. (Photo: K Swift)

Marl clays were long an important source of raw materials for ancient Greek potters. This is most aptly attested, for example, by Corinthian ceramics with their typical yellowish, extremely fine-grained fabrics used for Archaic fine wares and, with the addition of mudstone fragments from the Acrocorinth, for more substantial vessels such as the widely distributed Corinthian amphoras and large-scale corplastic production (Whitbread Reference Whitbread1995). Corinthian transport amphoras, louteria and mould-made Greek-type mortaria were observed in surface scatters at sites across Cyrenaica including Euesperides, Maaten el-Agla, Cyrene and Apollonia. Early Greek settlers in Cyrenaica, and particularly around Cyrene and the coastal plain below the Jebel Akhdar, would have had ready access to already familiar kinds of clay sources for local ceramic production.

In their raw state, marl clays were not usually used to produce cooking wares in ancient Greek pottery production. Their fine-grained matrices are susceptible to catastrophic propagation of microfractures from thermal stresses during use. Instead, ancient Greek and Roman cooking wares are usually coarse grained with frequent non-plastic material, often thermally conductive. But Cyrenaican marl clay fabrics are an unusual exception. Their abundant microfossil acts as natural tempering making these clays well suited for cooking wares – since thermal expansions of the calcareous clay bodies and microfossils are very similar, thermal stresses during repeated heating and cooling during use would have been reduced significantly while the relatively large microfossil inclusions would also inhibit the propagation of microfractures across the otherwise perilously fine and consistent fired-clay bodies.

At Euesperides and Berenice, these fabrics were used primarily for cooking wares which represent a distinctive local ceramic tradition characterised by: (1) primary forming techniques including hand-formed as well as wheel-thrown examples – this is the only fabric associated with hand-forming, with other fabrics and the majority of the coarse ware assemblages, being wheel-thrown; (2) secondary forming techniques evident in the usual burnishing of the vessel surfaces; and (3) the production of flat-based pans, paralleled functionally by imported Aegean cooking pans, which were not found in other local fabrics at Euesperides, although these were much less common than chytrai and lopades in these fabrics (Figure 6).

Figure 6. Examples of typical shapes in the distinctive hand-formed and burnished cooking wares in marl clay fabrics local to Euesperides. Scale 10 cm. (Illustration by K. Swift after D. Hopkins)

This distinct, circumscribed and highly local production tradition probably started from at least the late Archaic period at Euesperides and continued into at least the first century AD at Berenice (Riley Reference Riley and Lloyd1979). The burnishing technique probably follows that found on Aeginetan cooking ware imports, identifiable petrologically by their igneous inclusions and which are found at Euesperides in large numbers – almost one in four lopades are Aeginetan – as may the basic concept, though not specific morphology, of the flat-based pan which appears at Euesperides only in local marl clay and imported Aeginetan fabrics.

Perhaps the most striking feature from a technological perspective is that many of the pieces in this ware were hand-formed rather than wheel-thrown. This is extremely unusual for ancient Greek pottery production in general. They may have been produced domestically rather than by wheel-throwing in a workshop, although this would also represent a sharp contrast to the professional potter and workshop mode of production typical of the ancient Greek world.

As well as being produced locally at Euesperides (Swift Reference Swift2005, 69) and at Berenice (Riley Reference Riley and Lloyd1979, 94), marl clay fabrics have been identified at numerous other sites in Cyrenaica. On the coastal plain, they have been at Apollonia, Ptolemaïs, Tocra and Maaten el-Agla. On the Jebel Akhdar, examples have been identified from Balagrae. Marl clay fabrics containing microfossils are very common at Cyrene, found for example in plain wares and in roof tiles, and they were used for the production of Hellenistic braziers (Riley Reference Riley and Lloyd1979). The limestones and Shahat Marl underlying Cyrene contains pecten bivalves, which can be seen for example in the ashlar blocks in the pediment of the Temple of Zeus. They are a common feature in Cyrenean ceramic fabrics. Examples of fabrics with these inclusions were identified in Cyrenaican-type transport amphoras at Cyrene. A similar piece was identified at Euesperides (Swift in Wilson et al. Reference Wilson, Bennett, Buzaian, Buttrey, Fell, Found, Göransson, Guinness, Kattenberg, Morley, Swift, Wootton and Zimi2005), suggesting that it was a regional import produced from marl clays of Cyrenaica further to the east, plausibly from the area around Apollonia and Cyrene. As this example shows, the fossil inclusions in the source clays provide a promising means of intra-regional differentiation and sourcing of Cyrenaican marl clay fabrics through comparisons with the biostratigraphy. For example, the fabrics from Euesperides contain a single species, but a wider range of marine microfossils is present in the Derna and Al Beida formations of the Jebel Akhdar, and found in fabrics from Balagrae and Cyrene. Multisite, palaeontological study of marl clay fabrics holds the promise of identifying intra-regional distribution, as the example of a plausibly Cyrenean transport amphora from Euesperides suggests.

Sebkha (lagoonal) fabrics

These fabrics were produced from deposits associated with quiet-water sebkha (salt lagoon) environments. The origin of these fabrics is indicated by inclusions of shell fragments from quiet-water species and, at Euesperides, rounded grains of calcareous sand derived from weathering of the calcarenite bedrock of the Sidi Abeid. These diagnostic inclusions were also observed in hand-augured samples of clay-rich sediments from the sebkha adjacent to Euesperides. Sebkha fabrics appear in a range of textures and firing colours but are usually pale orange to reddish, approaching terra rossa fabrics – a continuum which may result from sediments washing into the lagoon. Some examples have iron-rich clay aggregates within them, firing reddish, which may be the terra rossa component which was either mixed in naturally or through deliberate addition (Figure 7).

Figure 7. Lagoonal fabric showing iron-rich clay aggregates from admixture of terra rossa sediments. Scale 10 mm. (Photo: K. Swift)

These fabrics are typically lightweight, porous and unusually friable, perhaps as a result of the high salt content. At Euesperides, these fabrics were used primarily for plain wares, particularly jug-like forms. The porous fabric probably helped to lower the temperature of the liquid contents through evaporation. Cooking wares do not appear to have been produced in these fabrics, which is not surprising given their friable and powdery consistency.

A production site with kiln and wasters in these fabrics was located and excavated within the urban area of Euesperides (Buzaian and Lloyd Reference Buzaian and Lloyd1996). Fabrics with similar textures were observed in the area of Alexandria, with its adjacent lagoon. A variant lagoonal fabric was also observed at Alexandria, resulting from lagoonal sediments mixed naturally with inflows of silt-rich sediments from the Nile Delta.

Admixture of clays and sediments

Sebkha fabrics seem likely to have been mixed naturally in the lagoonal environment. Admixture of other fabrics was likely intentional. Micro-textural, compositional, pyrotechnological and physical properties of clays could be altered through mixture with other types of clays and sediments, for example to increase workability and plasticity through the addition of calcareous marl clays or to increase physical strength and thermal toughness through the addition of finely granular, quartz-rich terra rossa sediments (Figure 8).

Figure 8. Tile from Cyrene showing admixture of marl clay and terra rossa sediments. Scale 10 mm. (Photo: K. Swift)

Admixture of marl clays with terra rossa sediments results in a continuum of compositions and textures, the fabrics mixed to varying degrees depending on the desired properties of intended product. It is therefore possible to classify an infinite number of ‘fabrics’ which are in fact produced from the mixture of two basic sediment types, which are themselves homogenous throughout Cyrenaica. Such a continuum serves as an example against classification based on minor differences in fabrics, but rather with reference to the petrological and geological environment and common features consistently encountered in large collections of pottery and other ceramics.

Argillaceous aggregations are a common feature and indicator of admixed fabrics. In poorly mixed marl clay-rich fabrics, the addition of iron-rich clays is indicated by clay concentrations of reddish, finely granular aggregates which are basically the same as terra rossa fabrics or sediments (for example, Figures 7 and 8). Conversely, the addition of marl clays to terra rossa fabrics, perhaps to increase workability of the clay, is seen in aggregates of calcareous, finer clay fired to a lighter colour than the deep reds typical of terra rossa fabrics. Finer, more plastic and workable, these marl clay aggregates seem to be much less common, perhaps because as pure clays they were easier to mix with coarser clays derived from quartz-rich terra rossa.

Admixed fabrics with marl clay and terra rossa components are common in Cyrenaica for ceramics which were produced on a relatively large scale and with a more complex and organised production, particularly black-gloss fine wares and Cyrenaican transport amphoras, as well as ones where there needed to be a trade-off between workability of the clay, drying shrinkage and structural strength, such as basins, Greek-type mortaria and other substantial vessels such as pithoi.

Cyrenaican fabrics in production, distribution and use

Articulations in fabrics, forms and functions are apparent in the pottery assemblages from Euesperides and pieces from other sites in Cyrenaica. Ceramic fabrics were produced from selected clay sources depending on the intended function of the fired vessels. The suitability of a particular clay source for particular vessel functions is clear in the assemblages from Euesperides. The physical properties of the fabrics could be modified based on careful selection of clays and manipulation through admixture with different sediments, including other types of clays. In this way, not only are the properties of ceramic fabrics derived from the kinds of clay sources selected for their production, linking the microscopy of fabrics to the macro-scale of geological processes, but they are also integral to the artifactual chaîne opératoire, from clay exploitation, manipulation, forming and pyrotechnology to distribution and use, before final discard and incorporation into the archaeological record.

Terra rossa fabrics are associated with all vessel types but make up the main fabric used for cooking wares at most sites. Marl clay fabrics are usually used for cooking wares at Euesperides and are associated with braziers from Cyrene. They were also used for roof tiles and architectural terracottas at Cyrene. Admixed fabrics produced from a combination of marl and terra rossa clays are usually found on non-cooking wares and on substantial vessels like pithoi, basins, louteria, Greek-type mould-made mortaria and roof tiles. Typically very porous, permeable and friable, lagoonal fabrics are mostly associated with jug-like forms including hydriai, where their permeability no doubt helped to keep the contents cool through evaporation.

Functional articulation of fabrics is also apparent in the imported wares at Euesperides, particularly those from central Greece. The articulation of Aeginetan cooking wares, Corinthian coroplastic ceramics and Attic fine wares provides an important example of the ways in which the physical properties of fired clays from different types of clay sources led to specialisation in large-scale production and distribution of ceramics around the ancient Greek Mediterranean.

Petrographic analyses of fabrics from Euesperides provenanced imported cooking wares from Aegina, which appear in the assemblages from Euesperides in significant quantities: nearly one in four lopades are Aeginetan imports. Attic black-gloss pottery is present at Euesperides (Zimi in Wilson et al. Reference Wilson, Bennett, Buzaian, Buttrey, Fell, Found, Göransson, Guinness, Hardy, Harris, Helm, Kattenberg, Morley, Swift, Wootton and Zimi2003), and it seems likely that these two wares were distributed together via the Saronic Gulf. Corinthian coroplastic ceramics in distinctive fabrics with argillaceous inclusions (Whitbread Reference Whitbread1995) are also present at Euesperides, including louteria and mortaria (Swift Reference Swift2005).

Produced on a very large scale, the major distributed types from these three areas correspond well to the properties of the fabrics which could be produced from their locally available clay sources; Aeginetan cooking wares with their heat-tolerant and conductive inclusions from weathered andesites; black-gloss and red-figure wares with their lustrous slips, produced from finely granular clays weathered from the Attic schist; and coroplastic vessels such as louteria and Greek-type mortaria produced in plastic, readily workable marl clays of Corinthia. As they are found at Euesperides, these imports comprise functionally articulated ‘distributed assemblage’ and connote a clear articulation in the main products of major production centres – an example of microscopic details having a bearing on macro-scale material-cultural interactions between different regions of the ancient Mediterranean.

The quantified assemblage from Euesperides indicates that these wares were distributed in quantity and they also provided models for local potters to emulate, sustaining consistent conceptions of shape in the wider Greek tradition. Adopted and adapted into pre-existing traditions, the geographically wide distribution of traded wares accounts for the relative conservatism in Greek shapes, making them easily recognisable typologically. But this also presents problems for the differentiation of local and regional wares based solely on vessel morphologies, which can be mitigated by combined study of forms, fabrics and production technologies. In this sense, ‘shape geographies’ are as important as shape histories for formulating and applying typologies and classifications to study of the archaeology of the ancient Greek world.

Future directions

Much has changed in Libya since the fieldwork conducted for this study in the early 2000s. The identification and provenancing of Cyrenaican fabrics has come to have an urgency and relevance beyond the academic. Ceramic fabric research and the wide dissemination of the results of such studies now has a critical role to play in provenancing and recovering looted ceramic antiquities which, though seemingly ubiquitous in archaeological contexts, represent the primary artifactual vestiges of our collective past.