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11 Overview

This thesis has sought to understand the use of vein quartz in the lithic repertoires of the prehistoric communities in Ireland. For much of the history of antiquarian and archaeological research, the story told of Irish flaked stone lithics was one of flint. Consequently, traditions of collecting and analysing lithics were developed using a framework, and worldview, based on flint. However, many other materials were used for stonecraft, a fact that was realised early on by Knowles but effectively overlooked by most. Where other materials were noted, these were considered as substitutes for flint rather than valid materials in their own right, or even as signs of a lower grade of peoples using them. This sense of flint as the premier material and others as second rate continues to this day. As with many myths, it is a hard one to displace. In terms of quartz, it is especially difficult to have it accepted as a valid material because many quartz assemblages can on first glance appear to be comprised of amorphous pieces, not easily recognised as humanly modified or forming ‘tools’. Even with these difficulties in identifying quartz artefacts, the database of quartz finds from Ireland compiled in this thesis has shown that the use of quartz for stone tools was widespread in prehistory. While quartz was certainly a material which saw special treatment, and used in special ways, it had a wider currency than in thanatopic contexts only.

In reviewing the quartz lithic research that has been undertaken in various parts of the world, two broad camps can be discerned – between those who argue that a separate typology is necessary, and those who maintain that quartz can be analysed in a framework devised for flint. For the latter group, a separate quartz typology would in effect get in the way of an easy and coherent typology of stone tools which can be compared to assemblages of other raw materials or in mixed assemblages. On the other hand, the researchers that have called for a separate typology for quartz have done so with the recognition that the fracture mechanics of quartz entail that fracture characteristics seen in materials like flint do not necessarily occur on quartz and that the prehistoric users used the differing fracture mechanics to their advantage in selecting pieces for use; therefore a schema devised with the fracture mechanics of the material as the lynchpin is crucial, with the fracture mechanics examined through the experimental knapping of quartz.

A part of this disagreement over the need for a separate typology is a result of what a ‘typology’ is. In the lithic studies’ literature there is a general division between typological studies and technological studies (e.g. Minzoni-Deroche 1985; Callahan 1987; Lindgren 1998; Inizan et al. 1999; Andrefsky 2001; Tomášková 2005; Ballin 2008); typological studies are generally geared towards results – the finished artefact; these ‘finished’ artefacts also include core ‘types’ in typologies. Technological studies are not restricted to typing ‘tools’, but concern the analysis of an entire assemblage to understand the mode of manufacture. Of course, the technological studies also use the same methods of typing in their analyses, hence technological studies are sometimes described as debitage typological analysis (e.g. Andrefsky 2001), or typotechnological analysis (e.g. Cornelissen 2003; Ballin 2008). As an example, a part of Ballin’s (2008) negative attitude towards a separate quartz typology stems from the distinction between a ‘typology’ implying a ‘tool’ typology, and that of a debitage typology; Ballin is more critical of the former than the latter, and needs a similar ‘tool typology’ in order to allow the easy comparative analysis of mixed material assemblages. While Ballin strongly rejects the imposition of a separate quartz typology, and argues that a flint typology works for quartz artefacts, he readily acknowledges (Ballin 2008, 73) that, technologically, quartz differs from flint, and quartz assemblages generally have less ‘formal tools’ and comments that quartz may have been used without retouch as tools. However, he is explicit on his stance of what a ‘tool’ is, and how to construct typologies: “a quartz artefact is not a tool unless it has the distinctive retouch generally associated with a particular tool type” (Ballin 2008, 40). From this, we can see that Ballin’s interpretation becomes a vicious circle – if a quartz artefact does not conform to a particular (flint) tool type’s retouch, it can be discounted as a tool, and therefore becomes lumped as ‘debitage’ even though he acknowledges they were probably used as tools without retouch.

The position taken in this thesis is that certain, highly formalised artefacts may have direct typological comparanda in alternative materials to flint, and that in these instances such relationships should be highlighted and no separate typology is needed. However, it will also be critical to understand those objects in terms of the technical sequences that have led to their formation – and that these sequences may not be comparable across materials; and a typology devised for the spectrum of cores and debitage products is called for in order to devise a framework for analysing quartz assemblages, beyond the gleaning for retouched tools, especially as quartz assemblages generally have low counts of retouch. Such an understanding can only be generated through detailed understandings of the properties of varied materials. What is now firmly recognised is that analyses based on formal tool types – tool types defined by archaeologists as ‘formal’ by the recognition of retouch – are only part of the picture of the prehistoric use of lithics; unretouched artefacts were tools (for examples of unretouched artefacts shown to have been used as tools see examples in Man 1883; White and Thomas 1972; Hayden 1979; Flenniken 1981; Symens 1986; Knutsson 1988a; Odell 1994; Banks 1996; Kozlowski et al. 1996; Read and Russell 1996; Finlayson and McCartney 1998; Briels 2004; Hardy 2004; Setzer 2004; Shott and Sillitoe 2005; Akerman 2006; Hardy et al. 2008), and a failure to recognise this produces a skewed picture of the archaeological record. Of course, the major dilemma facing the analysis of any assemblage is that the identification of retouched artefacts – the so-called formal ‘tools’ – is the easy part: the difficulty, in terms of time and expense, is setting up programmes of use-wear analysis to identify the non-retouched portion of the assemblage as having been used as tools, and not bracketing them off as ‘debitage’ or ‘waste’. Unfortunately, it was beyond the scope of this thesis to conduct use-wear analysis on the assemblages under scrutiny; consequently, this thesis should be regarded as the first step in the understanding of quartz technology in prehistoric Ireland. A useful next step would be the initiation of a programme of use-wear analysis on quartz artefacts.

The framework developed in this thesis for understanding the fracture mechanics of quartz was based on the experimental knapping of a variety of quartz sources, using a variety of methods of prehistoric stoneworking. Following initial results from these knapping experiments, a quartz recognition experiment was devised in order to assess the ability of people, with differing analytical skill levels, to identify and classify quartz artefacts. A third experiment subjected an experimentally knapped assemblage to burning in an open fire in order to assess the ability to recognise burnt quartz in archaeological contexts. The results of the knapping and burning experiments were then used to analyse two quartz assemblages – the primary case study was a Later Mesolithic and Neolithic quartz scatter from Belderrig, Co. Mayo, and the second case study was the quartz component from the excavations of a Neolithic palisaded enclosure from Thornhill, Co. Londonderry.

11.1 Experimental knapping

The quartz used in the experiments was collected from the vicinity of Belderrig Harbour, Co. Mayo, close to the case study excavation. Over 100kg of quartz was collected from four sources – from veins associated with psammite (a type of quartzite) bedrock exposed on the cliff face, from veins associated with metadolerite (a metamorphosed igneous rock) exposed in the intertidal zone, from beach cobbles which are a mix of quartz derived from the metadolerite and the psammite, and a vein associated with metadolerite located 1km from the harbour.

Samples of the different source materials were analysed macroscopically and in thin section by Dr Julian Menuge. The thin sections showed that the crystal size was 1-5mm making all of them coarse-grained raw materials and were variable in character in terms of crystal orientation and fracture development, but with all of them being of massive habit. The samples contained multiple macro- and micro-fractures, some of which led to the subsequent development of veinlets of quartz within them. When examining the quartz macroscopically, the large crystal size is not always apparent – while the quartz is defined as coarse-grained, the majority of it lacks the appearance of a sugary texture. Instead, the quartz appears as smooth-textured even though the thin sections clearly show the large individual crystal sizes, and the massive habit of the quartz and macroscopically it is difficult to distinguish the grain/crystal boundaries from macro-fractures. Compared to Ballin’s (2008) descriptions of quartz, the Belderrig material cannot easily fit. Ballin made a distinction between massive, milky quartz – which he described as the predominant quartz used in Scottish prehistory – and fine- and coarse-grained quartz. However, the Belderrig quartz is both massive, milky quartz and clearly coarse-grained, even though the graininess is often invisible, thus taking the appearance of a lack of grain. The thin sections, therefore, have highlighted the dangers of using macroscopic identification to interpret crystal/grain size and therefore through thin section it is possible that, for example, some of Ballin’s ‘milky quartz’ would be found to be in fact coarse-grained and of massive habit.

Approximately 30kg of the material was used to familiarise myself with knapping quartz and approximately 70kg of quartz was subsequently used for the 40 knapping events. The 40 knapping events consisted of knapping each of the four source materials twice for each of the five combinations of technique and support. The techniques used were hard and soft direct percussion and bipolar percussion, with the direct percussion using both elastic and inelastic supports. Here, the elastic support was my hand/thigh while the inelastic support was a stone anvil, with the anvil also used for the bipolar percussion. The hard hammers used for the direct and bipolar percussion were a collection of psammite cobbles collected from Belderrig Harbour and the soft hammer was a deer antler. As well as the 40 quartz knapping events, one chert block was knapped using hard hammer direct percussion in order to provide a baseline comparison to assess the fracture mechanics of the macrocrystalline quartz compared to the cryptocrystalline chert.

In order to ‘map’ the fracture characteristics of the materials, the recording strategy for the direct percussion component’s ≥10mm debitage was to collect and bag it per strike, thus allowing for rapid re-conjoining of the strike to assess the fracture patterns. For the bipolar technique’s eight events the recording was different because the process of bipolar knapping produces a series of cores and debitage; for these events the cores and debitage were not bagged per strike but instead were bulk bagged per event. In retrospect, it would have been preferable to also collect and bag the bipolar events in a similar fashion to the direct percussion, as this would have provided more detail as to the fracture characteristics of the materials, and mitigated possible discrepancies noted in the post-knapping analysis (for differences, see below). An added complication to the recording strategy was that it proved difficult to achieve – many of the smaller pieces, i.e. <20≥10mm, were not collected per strike because it proved too time consuming to collect each fragment. Consequently a lot of pieces were left on the drop cloth and bulk bagged at the end of each event for subsequent analysis.

These limitations notwithstanding, the knapping experiments provided a viable dataset of over 14,000 ≥5mm experimental artefacts to analyse which was sampled at 20% for full attribute analysis, apart from the direct percussion cores all of which were analysed. The sampling provided a quartz assemblage of over 2700 ≥5mm debitage weighing 10.5kg, 700g of <5mm debitage, 105 bipolar cores weighing 620g and 63 platform cores weighing 10.4kg.

In addition to the information provided on quartz knapping and fracture properties generally, the experimental knapping events were set up in order to identify possible differences between the methods and materials in the resultant assemblage. Overall, the four quartz source materials did not result in significantly different outcomes for most attributes recorded; there were just a couple of exceptions – such as with the interaction with technique/support in siret proportions where the beach quartz produced less siret breaks using bipolar compared to other materials, and more siret breaks using soft hammer direct percussion compared to other materials; for slivers the metadolerite quartz reversed the proportion of slivers produced with inelastic support compared to other materials. The technique/supports generally had a greater influence in the differences, where significant differences were discerned such as with the siret proportions and platform collapse. Therefore, for some attributes the materials used confounded the otherwise clearer pattern of the technique/support results, highlighting that the idiosyncrasies of the individual blocks/cobbles of quartz will affect the composition of vein quartz assemblages in unpredictable ways, but the materials only altered the patterns in interaction with techniques and/or supports. These four materials, therefore, generally behaved similarly. 

The clearest difference in materials, however, was between the chert and the quartz, which produced significantly different results for most of the attributes recorded such as the differences between the chert and quartz flakes’ length; the ratios of length/width and length/thickness; curvature; presence of bulb, compression rings, and eraillure flakes; the regularity of flakes; the difference in fragmentation rate of the debitage per strike and consequently the types of flake breaks produced; and the difference in core fragmentation rate. The quartz also needed different technical procedures during knapping than the chert; with incipient fractures developing on the core, the quartz cores needed to be tapped with an impactor occasionally in order to ‘complete’ these fractures, resulting in a series of fragmented pieces that were indistinguishable from other debitage produced during actual flake production. Similar indistinguishable debitage was also produced during core preparation in the form of edge trimming. The analysis of the fragmentation rate per strike of the quartz materials using direct percussion highlighted that each strike produces significantly more ≥10mm flake fragments compared to the chert component – on average, the chert produced 1.2 fragments per strike while the quartz produced 5.4 fragments per strike. Therefore, the quartz fragmentation rate is 4.5 times greater than the chert. In general the psammite quartz – which is the grainier, more sugary-textured quartz – produced the least amount of fragments per strike compared to the other quartz and the soft hammer inelastic also produced the least.

Table 11-1 provides a summary comparison of the chert and quartz experimental direct percussion. The significant difference between these materials is clear, as are the implications for analyses of archaeological assemblages. Taking Table 11-1 as a theoretical archaeological assemblage comprised of equal proportions of chert and quartz knapping, if the differences in the fracture mechanics of the various materials used are not taken into account misleading interpretations will inevitably result. If an assemblage which consisted of equal knapping of chert and quartz cores is tabulated, it will inevitably appear to be dominated by quartz debitage due to the significantly greater fragmentation rate, and a tabulation of complete flakes will make the chert component appear to dominate. Moreover, the relative ease of ‘reading’ the chert component can lead to the chert appearing as a more carefully crafted component of an assemblage, with the quartz knapping appearing as unstructured, crude, and, as Lindgren (1998) put it, without shape.

Characteristic Chert Quartz
Core composition Complete cores 20% core fragments
Debitage composition Almost all complete flakes Almost half debris, remainder mostly flake fragments
Complete flake morphology Long, narrow, thin Short, wide, thick
Flake fragmentation Almost all complete Almost all fragmented
Curvature All convex 43% straight; 51% convex; 6% concave
Flake regularity Almost all regular Almost all irregular
Bulb Always present Rarely present
Compression rings Always present Never present
Eraillure flakes Frequent Absent

Table 11-1 Experimental assemblage. Comparisons of direct percussion chert and quartz

The category of ‘debris’ highlights this notion of shapeless fragments. As noted, Inizan et al. (1999, 138) have defined debris as “shapeless fragments whose mode of fracture cannot be identified, and which cannot be assigned to any category of objects”. During the analysis it was noted that because the ≥10mm debitage was being recorded per strike, it was relatively easy to assign a mode of fracture and category to the debitage; in order to ascertain how the debitage would be categorised without this knowledge, a separate category was given in the database, the perceived category. For the Class category of ≥10mm debitage, the actual class (A Class) was comprised of 30% (n=628) debris, while for the perceived class (P Class) this jumped to 45% (n=934). Therefore, almost half of the experimental assemblage’s ≥10mm debitage consisted of shapeless fragments. The fragments that were re-categorised as P Class debris were mainly mesial and sequential fragments (the sequential fragments often formed when a fragment was removed from either the dorsal or ventral face of the debitage) highlighting that these two fragment types are the most difficult to identify with certainty and will therefore be under-recognised in assemblages. Because of the difficulties in consistently identifying sequential breaks and fragments, these categories were excluded from the subsequent analysis of the archaeological assemblages.

The fact that almost half of the experimental debitage was categorised as debris could make one despondent with attempting to analyse assemblages produced on coarse-grained vein quartz such as that from Belderrig, and view these ‘shapeless’ fragments as no more than gravel. Nevertheless, while this 45% of debris is substantial, and in many ways disquieting, the remaining 55% is more than amenable to analysis, and clear patterns of debitage formation and breakage were discerned. The analysis of the complete and platform flakes has shown that a number of characteristic platform attributes are identifiable, albeit with a number of complicating factors such as edge damage that forms during knapping and which can result in pseudo-platforms forming on non-proximal flakes, and fragmented platforms appearing as complete platforms due to sequential fracturing. While the platforms on bipolar flakes are generally distinct from the direct percussion platforms, a sizable proportion can take the appearance of direct percussion flakes, especially if the platforms are fragmented. 17.1% of the ≥10mm bipolar debitage and 22.6% of the bipolar flakes appeared to be platform flakes, while 2.6% of the ≥10mm platform debitage and 4.6% of the platform flakes appeared as platform flakes. This highlights that it is more likely that bipolar flakes will be underestimated in an assemblage compared to platform flakes. For direct percussion, and especially bipolar percussion, bulbs were infrequent, and compression rings were only noted on two direct percussion flakes. These two flake attributes, which are generally discussed as characteristics that identify humanly-struck flakes, are not very useful in assessing assemblages formed on coarse-grained quartz.

Compared to the direct percussion, the bipolar component had a significantly greater proportion of complete flakes at a third of the flakes, with the direct percussion producing less than 8%. This may be related to size, with less surface area available for fragmentation. However, the different recording strategies may have slightly exaggerated the proportion of apparently complete bipolar flakes – as the bipolar debitage was not bagged per strike, it was difficult to identify sequential breaks and fragments; consequently, some of the bipolar flakes that were assigned as complete may in fact be flake fragments with indistinguishable sequential breaks; the surface of the quartz makes it difficult to assess the completeness of flakes compared to flint or chert. However, the bipolar knapping produced less debris, highlighting that the bipolar technique does not produce a multitude of shapeless fragments as witnessed with the direct percussion.

In terms of differences between the soft and hard hammer direct percussion, little difference was discerned between the complete flakes. While on average the complete soft hammer flakes were larger and thicker than the hard hammer flakes, the differences for all the metrics were not statistically significant and therefore were not adequate predictors of technique or technique/support. The soft hammer component was also less likely to exhibit the strike’s impact mark on the platform compared to the hard hammer direct and bipolar flakes. This analysis, however, indicated that the proportion of siret breaks is a useful predictor of the technique/support used. The analysis of the proportions of siret breaks showed that the soft hammer produced significantly less siret breaks than the hard hammer or bipolar regardless of the quartz source, and that the use of the platform-on-anvil reduced the occurrence of siret breaks for both soft and hard hammer, but that using the beach quartz both increased and decreased the likelihood depending on the technique/support. The proportion of flakes with platform collapse was also analysed, with no significant difference between the techniques, highlighting that this variable is not a good predictor of technique. However, differences were discerned with the support used – the use of a platform-on-anvil method of knapping significantly increased the likelihood of platform collapse compared to freehand percussion. Table 11-2 provides a summary of the differences between soft and hard hammer flakes, highlighting that the only statistically significant difference is the proportions of siret breaks.

Characteristic Soft hammer direct percussion Hard hammer direct percussion
Flake morphology Generally longer, wider and thicker Generally shorter, narrower and thinner
Platform size Generally thicker Generally thinner
Impact mark Present on 79% Present on 96%
Breakage Significantly less siret breaks* Significantly more siret breaks*
Platform collapse Slightly more Slightly less
Curvature More straight More curved
Flake regularity Almost all irregular Almost all irregular
Bulb Slightly more apparent Slightly less apparent
Compression rings Never present Never present

Table 11-2 Experimental assemblage. Comparisons of direct percussion hard hammer and soft hammer flakes. * denotes statistically significant differences

The analysis of the cores has shown that the process of core fragmentation complicates the interpretation of assemblages. Overall, 10% of the platform cores fragmented, resulting in a platform core assemblage of 21% core fragments – many of these core fragments are indistinguishable as core fragments, possibly resulting in an under-recognition of cores in archaeological assemblages and a consequent over-count of debitage. Neither the beach quartz nor the psammite quartz – both the sugar-textured quartz – produced core fragments; nor did the soft hammer elastic knapping events. For the platform cores knapped on inelastic supports, all but one core fragment set had indicative distal impact marks signifying the use of an anvil, as did the bipolar cores which also had proximal impact marks. The bipolar core assemblage produced a greater proportion of core fragments, but the bipolar component are overall easier to identify as bipolar cores and bipolar core fragments. One difference noted to Knutsson’s (1988a) experimental dataset was the occurrence of conical pieces, which he states as occurring from both bipolar and direct percussion knapping. In this series of experiments, all the conical pieces resulted from bipolar reduction, and were treated, cautiously, as bipolar core fragments.

11.2 Quartz recognition experiment

The initial analysis of the experimental assemblage made it clear that the correct identification of a given artefact’s place in the chaîne opératoire was often problematical especially with non-proximal flake fragments and core fragments thus leading to incorrect interpretations. As the experimental assemblage’s debitage had been for the most part divided into strike piles, the fragmentation of a given flake could be reconstructed through conjoining – once this possibility of conjoining was taken away and the analysis was done ‘blind’, as would be the case in an archaeological assemblage, the results were quite different. In order to evaluate how people with different analytical skill levels recognise and categorise quartz artefacts, a quartz recognition experiment was designed and held during the 2008 excavations at Belderrig, and subsequently held during the World Archaeological Congress (WAC) conference held in UCD, in July 2008.

A selection of platform and bipolar cores and debitage were selected from the experimental assemblage and presented to the participants. The participants were not told that the artefacts were from the experimental assemblage, but instead were told that they were ‘Belderrig quartz’ – which the experimental artefacts were made from. The reason for avoiding a description of the artefacts as deriving from the experimental assemblage was in order to maintain the possibility that some pieces were not anthropogenic in origin – as one might anticipate in an archaeological assemblage but not in an experimental one. Furthermore, I was concerned that if the quiz had taken place with participants knowing that a definitive answer existed interpretations may have been affected by this knowledge. Both factors seemed very important in terms of testing an archaeological typology (where prior knowledge does not usually exist).

Due to differences in the presentation of the quiz to the participants at Belderrig and WAC, these were not analysed together, and the main analysis is based on the WAC experiment which had a greater number of participants, and included analysts with substantial experience in analysing quartz assemblages. 47 participants took part in the experiment at WAC. The participants were asked to self rate their experience with analysing lithics in general and quartz lithics in particular. 62% had substantial experience in lithic analysis and 23% had substantial experience with analysing quartz specifically; of those with no experience with quartz, 36% had substantial experience with lithic analysis.

The participants were asked to identify and classify the quartz in a manner generally done with lithics – the first category of Piece divided the artefacts into either cores, debitage, indeterminate, or natural. The second was Type, which for the cores was dividing them into core types, and for the debitage dividing them into flakes or debris. The third category was to sub-divide the debitage into regular platform flakes, irregular platform flakes, or bipolar flakes. The participants were also asked to note if the artefacts were complete or fragments, and also to note any case of modification, i.e. retouch.

The results of the recognition experiment highlight that the ability of the participants to correctly identify and classify the artefacts was low, demonstrating the significant difficulties in recognising quartz artefacts even for archaeologists with substantial experience in analysing lithic assemblages and specifically quartz assemblages. While some of the individual participants fared better than their peers with similar skill levels, taken as a skill level cohort, all the cohorts fared poorly. Overall, the over-recognition rate of retouch was 9%, which broadly matches findings by Lindgren (1998). Those with substantial experience with analysing quartz generally had a greater success rate at both identifying flaked quartz as non-natural and also categorising it into its respective types. They were also less likely to note occurrences of retouch on the non-retouched artefacts. Nevertheless, the difference in scores was often slight, and statistically, apart from a few instances, the skill levels were not a good predictor of the participants ability to answer correctly.

Some of the artefacts presented to the participants, especially the platform core fragments, were surmised to be difficult to correctly identify and classify and this proved correct. One of the more surprising and unexpected results was the misidentification of the bipolar component of the experimental assemblage. As noted in Chapter 4, the linkage between bipolar technology and quartz is experienced worldwide, so much so that many analysts have needed to stress that the two do not always necessarily have to go together, and indeed, that quartz technology is viable without the use of a bipolar strategy. Given this relationship, it is very surprising that the bipolar artefacts, or at least the bipolar cores, were consistently misidentified and misclassified by the participants, even those with substantial experience with analysing quartz. Significantly, when those with substantial quartz experience did judge a piece to be a bipolar core, they were only correct 55% of the time. They were incorrect as they mistook both platform core fragments and a platform flake for bipolar cores. The compiling of a consensus assemblage highlights that the bipolar component of the assemblage, which comprised 30% of the actual assemblage, was considerably under-represented – none were noted in the consensus assemblage of the minor quartz experience cohort, and just one in the substantial quartz experience cohort, which, ironically is actually a misidentification, as the ‘bipolar core’ that they agreed upon is one of the platform core fragments.

11.3 Burnt quartz experiment

In order to develop a framework for identifying and qualifying burnt quartz in archaeological assemblages, an assemblage of 280 artefacts, knapped using the same four quartz sources as in the experimental knapping assemblage, were burnt in an open fire. The artefacts were selected by size, providing 10 artefacts from each source material for each of the seven size grades. The remaining unburnt part of the assemblage was retained in order to compare to the burnt material. Three effects were investigated; the visible signs of burning, the fragmentation rate of the quartz, and the spatial distribution of artefacts.

The effect of burning on the visual characteristics of the quartz was apparent immediately on placing the artefacts in the fire, with the assemblage turning a snow white from the general metallic grey hue. However, differences were apparent between the materials, with the Rose Cottage quartz component changing hue to a lesser degree than the other materials. The quartz with more abundant impurities changed as well, from grey and yellow to burnt orange and pink. The change in opacity was apparent for all materials but varied; for the metadolerite quartz, the least granular of the quartzes, the change was the most uniform, while for the beach quartz the change was slighter. The burning dulled all the materials, giving them a less vitreous appearance; this was especially the case for the metadolerite quartz. The lustre of the quartz is difficult to be precise about, and difficult to assess possible heat related changes without a similar sample to compare with. All the materials were still in effect vitreous, just less so. There was no difference in the granularity of any of the materials. The only effect noted was that the hue change created a contrast, accentuating the grain texture – this accentuation of grain texture might be due to some grain boundaries becoming the sites of macrofractures (Menuge 2009a pers. comm.): however, this effect was slight. The burning also increased the amount of visible macrofractures on the artefacts. While Ballin (2008, 51) noted pitted and peeled off surfaces as characteristic of burning, neither of these were visible on the Belderrig burnt quartz.

The effect of burning on the fragmentation of the quartz artefacts was dramatic, with a greater than fivefold increase in the assemblage’s quantity.  The 80 ≥35mm artefacts were reduced to 61, while the ≥15<25mm size grades almost doubled in quantity. The most dramatic difference was the smaller artefacts – <15mm artefacts initially accounted for 14.3% of the assemblage, and after burning they accounted for 80.5% of the assemblage, with the <5mm artefacts accounting for the majority of that proportion. The ≥1<10mm began with no artefacts and ended with 1128.

The spatial analysis of the hearth has shown that, while the quartz fractures dramatically, there is less of an explosive expelling of artefacts from the hearth than with flint (see Sergant et al. 2006). Very few artefacts were expelled outside of the hearth, with most movement occurring over centimetres, resulting in a reasonably contained final hearth spread. The lack of explosive movement compared to the flint may relate to the lesser proportion of fluid in quartz compared with flint, resulting in less pressure during heating. In terms of a comparison to the fragment rate with the flint, this is not possible, as Sergant et al. (2006) do not provide a breakdown of the pre- and post-burn size grades.

In terms of macroscopic visual characteristics of burnt quartz in archaeological contexts, therefore, a key consideration is what an unburnt sample of the raw material looks like. While a given artefact may appear as dull, opaque, with numerous fractures, the source of that material should be examined to determine whether the dullness and opacity is related to its source or burning; multiple fractures are not a useful characteristic for identification as these are common anyhow. The impurities, such as iron, in the quartz changed their hue the most, therefore these can be a useful indicator of burning. In terms of the microscopic visual characteristics, the thin sections have shown that the decrepitation of fluid inclusions is a signature of burning at high temperatures. The dramatic fragmentation of the quartz artefacts has serious implications for any analysis of a burnt quartz assemblage, or assemblages that contain burnt quartz. Problematically, it was noted that the multitude of smaller fragments produced during burning are the most difficult to identify as being burnt. Assemblages with significantly high proportions of smaller fragments may suggest evidence of burning, other depositional and post-depositional factors notwithstanding.

11.4 Case studies

Following from the frameworks developed for understanding the fracture mechanics and burning of the quartz and in the experiments, two assemblages were analysed – a Mesolithic and Neolithic quartz lithic scatter from Belderrig, Co. Mayo and a quartz assemblage from a Neolithic palisaded enclosure at Thornhill, Co. Londonderry. While the rock crystal and non-quartz material have been referred to, the primary focus of analysis is on the vein quartz components, comparing them to the experimental knapping assemblage. Section 11.4.1 first provides a comparative overview of the quartz artefacts, followed by in Section 11.4.2 an overview of the case studies’ contexts.

11.4.1 Assemblage comparisons

As well as chronological and geographical differences, the two case study assemblages are derived from fundamentally different contexts – one an excavation of a small trench with a high artefact density, the other a part excavation of a large settlement with a much lower artefact density. Their unifying theme for this thesis, however, is that both are quartz assemblages, and they pose similar questions. One overriding question is how an understanding of the fracture mechanics might aid the interpretation of the assemblages, and help analyses move beyond the gravel effect, as coined by Callahan (1987), whereby quartz assemblages are viewed as composed of amorphous pieces.

The category of debris is in effect a non-category – a category used when amorphous artefacts cannot otherwise be placed in other categories. While very few of the >20mm experimental debitage produced were categorised as debris, the problematical pieces were generally the debitage between 10mm and 20mm – 45% (n=934) of the ≥10mm debitage was categorised as debris, with the bipolar knapping producing less debris than the direct percussion. Both Thornhill and Belderrig contained greater proportions of >20mm debris than the experimental dataset (Figure 11-1), highlighting that compared to a ‘fresh’ assemblage, archaeological assemblages will inevitably include more larger amorphous fragments due to taphonomic processes.

debitage proportions

Figure 11-1 =10mm Debitage proportions: flakes, debris, and slivers. Experiment platform, Experiment bipolar, Belderrig, and Thornhill assemblages

While the Belderrig assemblage was close to the experimental direct percussion dataset in terms of flake proportions, the Thornhill assemblage was close to the experimental bipolar dataset even though the Thornhill assemblage was dominated by direct percussion flakes (Figure 11-1). 14% of the Thornhill flakes were bipolar; however, bipolar flakes may have been under-counted. Looking at only Thornhill flakes with striking platforms, 21% were bipolar flakes. Analysis of the experimental assemblage highlighted that while the platforms on bipolar flakes are generally distinct from the direct percussion platforms, a sizable proportion can take the appearance of direct percussion flakes, especially if the platforms are fragmented – 17.1% of the ≥10mm bipolar debitage and 22.6% of the bipolar flakes appeared to be platform flakes, while only 2.6% of the ≥10mm platform debitage and 4.6% of the platform flakes appeared as platform flakes. Therefore about 20% of the flakes at Thornhill may in fact be bipolar flakes. It is unlikely, however, that it is much higher than this, as the majority is clearly direct percussion. The high proportion of flakes in the Thornhill assemblage compared to the other datasets suggests that none of the Thornhill contexts appeared to represent a knapping floor assemblage. While Thornhill did not have a greater proportion of complete flakes, and far less complete bipolar flakes than the experimental bipolar dataset, it contained a high proportion of proximal flakes suggesting the selective importation and deposition of proximal flakes (Figure 11-2). The experimental direct percussion and the Belderrig assemblages have similar patterns of fragment proportions.

debitage proportions

Figure 11-2 =10mm Debitage P Fragment proportions. Experiment platform, Experiment bipolar, Belderrig, and Thornhill assemblages

The proportion of cortical debitage was significantly different between the experimental and archaeological datasets. Figure 11-3 provides the proportions for the experimental datasets for both the overall quartz and the beach quartz alone, highlighting that the differences in cortex proportions is not solely due to the use or non-use of beach cobbles; the bipolar and platform datasets also produced similar cortex proportions.

For the Thornhill assemblage it was posited that the low proportion of cortical debitage suggests that the debitage assemblage does not represent a knapping floor assemblage to a great degree, and that the ‘missing’ cortical flakes are either elsewhere in the unexcavated areas of the site, or at a further remove from the site altogether. However, there was also a high proportion of >49% cortex bipolar and platform cores suggesting that the cores were not decortified by the communities of practice before being brought to the site for use or deposition (85% of both bipolar and platform cortical cores from Thornhill were identified as beach cobbles). Therefore, there is a clear mismatch in the cortex proportions between cores and debitage indicating a complex pattern in the chaîne opératoires of core and debitage use and deposition throughout the site’s contexts.

debitage cortex proportions

Figure 11-3 =10mm Debitage cortex proportions for experimental and archaeological assemblages' bipolar and platform debitage. The experimental assemblage is also presented for all quartz source materials and beach quartz only

For the Belderrig assemblage, the low proportion of cortical artefacts suggests that the communities of practice’s chaîne opératoires involved the initial knapping of cobbles/blocks began away from the excavated trench area, with cores being brought to that area once decortified to some extent, as well as having bedding planes removed. The overall low proportion of cobbles suggests the a greater emphasis on quarrying of vein quartz. While the overall proportion of cortical artefacts was low, the earlier contexts contained significantly greater proportions than the later contexts, suggesting a difference in the chaîne opératoires of the communities of practice over time. This difference may relate to a lesser degree of initial knapping taking place away from the excavated area during these earlier contexts and/or with more beach cobbles used in these contexts, and also a lesser degree of decortification of quarried blocks. For the quarried blocks, an alternative explanation is that quarried veins, which had been previously opened and consequently decortified, were subsequently quarried further during later contexts with less cortex on the material as it had been decortified already. This interpretation would suggest that the same veins were re-visited for use over the generations.

While the Thornhill assemblage was more beach cobble-based than Belderrig (see Table 11-3 for summary comparison of the assemblages), for both of the archaeological assemblages there was a clear preference for smooth-grained quartz in the assemblage, which was noted during the experimental knapping to have a higher rate of fragmentation per strike than the more sugar-grained material. If this fragmentation pattern also held for the prehistoric communities of practice, it may imply that a higher fragmentation rate of materials was not an attribute to be avoided, and/or that characteristics of the material such as the smooth-grained appearance were more sought after than the apparently functional attributes of lesser fragmentation rates. Experimental work on the use of the differing quartzes would shed light as to which types of graininess is suitable for differing tasks in term of edge sharpness and edge maintenance/damage resistance.

There were significant differences in the methods of knapping noted between the two archaeological assemblages. While at Belderrig there was no evidence for platform preparation such as faceting or abrasion in the chaîne opératoires, but rather the cores were primarily knapped directly using direct percussion, using both freehand and platform-on-anvil. In the earlier contexts there was a lower proportion of bipolar cores, with the later context containing a higher proportion suggesting a Neolithic component in the assemblage; the direct percussion artefacts from the context, however, do not appear to be significantly different from the earlier contexts in terms of the chaîne opératoires. Furthermore, while a considerable proportion of the cores from C.202 were bipolar, there is little evidence of in situ knapping, with just one bipolar flake noted. This may suggest that during the Neolithic material was deposited onto a previous collection of quartz artefacts.

Characteristic Belderrig Thornhill
Flake type 99.9% platform flakes 86% platform flakes
Platform flake morphology Short, wide, thick Small, wide, thin
Proportion complete flakes 5% of flakes 5% of flakes
Proportion diagnostic types 1% of assemblage 16% of assemblage
Diagnostic types Primarily retouched flakes Primarily retouched flakes; 18% scrapers
Retouched flakes Larger than non-retouched Similar size to non-retouched
Cores 16% of assemblage 1% assemblage
Beach cobble cores 11% of cores 53% of cores
Technical procedures - Platform preparation, abrasion, faceting
Core types[29]
Platform 80% - primarily single platform 34% - primarily multiplatform
Bipolar 15% 54%
Bipolar/platform combine - 7%
Radially split/conical piece 2% 6%
Conical piece 4% -
Complete platform flake (mean)
Length (mm) 27.9 20.3
Width (mm) 25.5 20
Thickness (mm) 13.4 8.2
Weight (g) 18 5.6
Length/weight ratio (median) 4:1 9:1
Complete platform core (median)
Length (mm) 56.9 45.3
Width (mm) 44.3 37.7
Thickness (mm) 36.5 27.5
Weight (g) 100 48.1
Complete bipolar core (mean)
Length (mm) 27 36.3
Width (mm) 15.3 27.6
Thickness (mm) 12.8 20.7
Weight (g) 5.6 30.3

Table 11-3 Summary comparison of Belderrig and Thornhill vein quartz assemblages

In contrast the chaîne opératoires of the Thornhill communities of practice involved platform faceting, preparing, and abrading, and the techniques/supports included bipolar, direct percussion freehand platform, direct percussion platform-on-anvil, indirect percussion, bipolar-on-platform, and platform-on-bipolar; half the cores were bipolar. The communities of practice at Thornhill do not appear to have used the bipolar technique to reduce small platform cores further, as is noted in other lithic traditions (e.g. Callahan 1987; Knutsson 1988a; Ballin 2008). Indeed, many of the complete bipolar cores are larger than the complete platform cores, indicating that the latter were frequently knapped to a smaller size. Neither is this difference related to the quality of the quartz, as similar quartz was knapped with both techniques.

None of the Belderrig cores resemble classic Later Mesolithic Larnian uniplane cores. The examples of single platform cores were usually knapped at up to 90% of the platform circumference and the single platform cores were generally subsequently rotated, resulting in dual, opposed cores or rotated again resulting in multiplatform cores; 80% of the platform cores were multiplatform. The absence of uniplane cores is not, however, problematical from a typological perspective – the Ferriter’s Cove excavations highlighted that a low amount of uniplane cores can be expected on Later Mesolithic sites, with the uniplane core a by-product of a certain method of working and not a strict template to be followed (Woodman et al. 1999).

While multiplatform cores dominated the Belderrig assemblage, at Thornhill single platform cores dominated the platform core component, with the dual, right angled cores a distinctive difference to the Belderrig chaîne opératoires. The Thornhill platform cores contained a much greater size range and substantially smaller cores compared to the Belderrig assemblage, with the Belderrig cores producing a tighter cluster of cores in the middle and upper range of length/width/thickness. Overall, the Belderrig platform cores’ means for all metrics were significantly greater, with smaller standard deviations, and a much lower length/weight ratio which is the result of much thicker cores.

The Belderrig knapping appears geared towards the production of short, wide, thick flakes, with many of the flake fragments of similar dimensions, if not larger, than the complete flakes. Along with the thousands of non-retouched flakes, many of which can be considered as tools, a small number of diagnostic types were identified including a butt trimmed flake, a borer, and a point/notched piece; besides these, the rest were predominantly retouched flakes while one with abrupt retouch on its distal end could be considered scraper-like. None of the cores were retouched, while one retouched artefact was categorised as a core/debitage. Compared to the non-retouched artefacts, the diagnostic artefacts were significantly larger in all dimensions and weight. While there is therefore a clear distinction in terms of size between the retouched and non-retouched artefacts, it is difficult to discern if the retouched artefacts represent the reuse of non-retouched tools, or if they represent a different kind of tool which necessitated retouch, and larger size of artefact, from the outset. Just one ‘classic’ Later Mesolithic type – a butt trimmed flake – was noted. Other flakes are morphologically similar to butt trimmed types, minus the retouch. The Ferriter’s Cove site also had a low proportion of butt trimmed forms, and overall the flaked stone assemblage consisted of 0.5% (n=36) “retouched tools” (Woodman et al. 1999, 29, 76), while the Belderrig quartz assemblage consisted of 0.6% retouched artefacts and if the possible retouched artefacts are included this increases to 1%; the non-quartz component consisted of 3.2% (n=2) retouched artefacts. Therefore, the Belderrig quartz assemblage does not appear to have a lower proportion of retouched artefacts compared to Ferriter’s Cove at least.

In terms of the use of the non-retouched debitage from Belderrig, the apparent lack of slivers, and in some contexts of mesial fragments, was suggested as possible evidence for the removal of such artefacts from the area for use. Considering the communities of practice’s location at a coastal site, a possible interpretation for these small fragments is the use in fish processing. Flenniken (1981) noted that small, non-retouched fragments of vein quartz were hafted for use as fish processing tools, with these erstwhile non-diagnostic pieces of quartz noted as functional tools because they were found hafted in waterlogged contexts; while there, the communities used bipolar reduction to specifically produce such artefacts, at Belderrig a possible interpretation is that such fragments were a useful by-product of the communities vein quartz chaîne opératoire, and a use of the fracture characteristics of the quartz.

The Thornhill knapping appears to have been geared towards small, wide, thin flakes, with almost no blades noted in the assemblage. The Belderrig’s complete flake median length/weight ratio was 4:1 while Thornhill’s was 9:1, highlighting the considerable comparative thinness of the Thornhill flakes. While the Thornhill non-quartz assemblage consisted of over a third diagnostic types, the quartz component contained a much smaller proportion at 4.9% of the assemblage, which is nevertheless significantly greater than the Belderrig assemblage. Unlike the Belderrig diagnostic types, the Thornhill diagnostic types’ means for the various metrics were not significantly different than the non-retouched artefacts. Overall, there were seven scrapers, two borers, one retouched pebble, two retouched cores, one retouched bipolar flake, 24 retouched platform flakes, and three retouched debris. One scraper was on a bipolar core while another was on a core/debitage with the remainder on platform flakes. Scrapers on flakes with plunging terminations were noted, and the higher proportion of flakes with plunging terminations compared to the Belderrig assemblage suggests that the chaîne opératoire included the purposive knapping of plunging flakes for subsequent use as scrapers which was also noted for the non-quartz assemblage (Nelis 2004). For the 24 retouched flakes, the most common type of retouched flake had abrupt, rectilinear retouch on lateral edges.

Both Mesolithic and Neolithic assemblages had evidence for platform-on-anvil knapping. There has been little discussion of the platform-on-anvil technique in Irish lithic research. A notable exception to this lack of discussion is Nelis’ (2004, 866) research on Neolithic assemblages from Northern Ireland, which included the identification of platform-on-anvil cores. However, two assemblages may point to its use in the Later Mesolithic besides with quartz at Belderrig. At Ferriter’s Cove Woodman et al. (1999, 32) noted for the flint cores “areas of severe damage are visible on a number of distal ends of single- and dual-alternate platform cores…Although this implies the use of an anvil support, there is little typological or refitting evidence for the use of the bipolar technique”. While in a lithic scatter from Corralanna Warren et al. (2009, 15) noted the discovery of a large stone with pitting, interpreted this as an anvil but commented that “the absence of any evidence of bipolar techniques in the assemblage suggests that this pitting results from activities unrelated to stone-working tasks”. Both of these analyses looked for evidence of bipolar cores specifically rather than for evidence of platform-on-anvil knapping. This may suggest that this type of technique was more prevalent than has been appreciated.

The low proportion of siret breaks in the Mesolithic assemblage at Belderrig was interpreted as suggesting the use of soft hammer by the communities of practice there, as well as the additional evidence of the low proportion of impact marks on the flakes with complete platforms. At Thornhill, however, while the proportion of siret breaks was also low, 100% of the complete platforms exhibited impact marks, suggesting hard hammers. This is a reversal of what had been expected for the different lithic traditions. At the outset of the experimental knapping, it was surmised that the Mesolithic would be hard hammer-based, while the Neolithic lithic traditions may have included soft hammer percussion.

Both soft and hard hammer reduction have been noted in Irish Early Mesolithic but which attributes were used to distinguish between the techniques were not indicated (Costa et al. 2001), while for the Later Mesolithic the use of hard hammer has been identified by “the variation in platform size, the number of prominent bulbs of percussion, and the broad flake scars on many of the cores” (Woodman et al. 1999, 71); for some Neolithic assemblages, soft hammer flakes have been noted but not defined (Brady 2001, n.d.-a, n.d.-b), while for others they have been identified and distinguished: “hard hammer…produces flakes with platforms…[and] soft hammer…sometimes produces flakes with no platforms” (Milliken 2002a, 2002b). Redman (1998, 90-1) argued that the results of her analysis of an assemblage produced by three knappers using both techniques suggested that categories of ‘hard hammer flake’ and ‘soft hammer flake’ “are, in a sense, meaningless” – greater variability was seen between the three different knappers rather than impactor and the only variables immune to idiosyncratic knapper difference were the bulb thickness, max thickness and midpoint thickness; while immune to knapper difference they were nevertheless only weak at distinguishing between impactor type.

In terms of the attributes noted by Woodman et al. (1999, 71) for hard hammer, similar attributes were produced using a soft hammer during the present experimental quartz knapping. This suggests that further research is needed on both quartz and non-quartz materials to test the ability to distinguish between hard and soft hammer techniques in Irish lithic traditions. And Redman’s (1998) warning that experimental knapping should be conducted by more than one knapper to distinguish which attributes are created by the idiosyncratic nature of individual knappers is important. The difficulty with predicting the use of soft hammer on the basis of the proportion of siret breaks is that an archaeological assemblage will not include the exact proportions of artefacts of a ‘fresh’ knapping floor such as the experimental knapping, and the proportion of siret breaks may be altered by the removal or addition of debitage in the area. This was the case for the Thornhill assemblage, but may also apply to the Belderrig scatter, where it was shown that there was a mismatch of materials and artefacts within the assemblage. Additionally, it is possible that the knapping expertise of the communities of practice at Belderrig, along with the method/technique employed with a hard hammer, may have resulted more closely with what was achieved with a soft hammer during these experiments, i.e. thicker flakes less likely to form a siret breaks.

The quartz burning experiment showed that changes in hue are apparent in burnt quartz, with these changes apparent on larger pieces and where the original hue of the quartz is known. For the Belderrig assemblage only 11 artefacts (0.2% of total) were noted as burnt (n = 1) or possibly burnt (n = 10). As 10 were described as possibly burnt the 11 may represent an over-count of actual burnt artefacts, suggesting that the Belderrig assemblage did not witness burning to a great extent. For the Thornhill assemblage 19 artefacts were burnt (n=2) or possibly burnt (n=17). The two burnt artefacts were cores, while the possibly burnt were all debitage. The pits are over-represented with the burnt or possibly burnt artefacts, with three of the seven from the pits coming from one pit. For the non-quartz component 19% of the assemblage was burnt/heated, with 15% described as heavily burnt; 13% of the “modified assemblage” was also burnt (Nelis 2004, 298-9). This proportion is at odds with the quartz component, which had 2.3% burnt or possibly burnt artefacts – this significant difference cannot be put down entirely to the difficulties in identifying burnt quartz, and may result from a different treatment of materials, or different contexts of burnt material.

11.4.2 Site contexts’ overview

The two quartz assemblages in many ways typify the differing site ‘types’ and excavation contexts of the Later Mesolithic and Neolithic periods in Ireland. The Belderrig Mesolithic assemblage was a research-led excavation consisting of an accumulation of lithics, some ephemeral features, and the construction of a stone platform of sorts, while the Neolithic component at Belderrig is associated with the construction of stone walls; the Thornhill Neolithic assemblage was a development-led excavation consisting of an accumulation of lithics and numerous features such as a series of palisades, substantial structures, and a plethora of pits.

While these different contexts contrast strongly, they do not involve, however, a stereotypical dichotomy between ephemeral, acultural hunters (fishers/gathers) and concrete, cultural farmers. But they did involve changes in the landscape of which people, animals, and plants, and (from a modern perspective) inanimate objects like quartz together formed, and changes in peoples’ relationship with the landscape and its inter-related parts, including quartz. From a taskscape perspective – which recognises life as a sequence of inter-related activities and an enaction of fundamentally social technological practices that encompassed the entirety of communities’ world and world-view – these changes clearly shaped and affected the quartz chaîne opératoires.

The quartz scatter from Belderrig is part of a larger assemblage excavated on a hillside overlooking the mouth of a river at Belderrig Bay, North Mayo. The portion of the Belderrig assemblage selected for analysis consisted of over 5000 vein quartz artefacts, with a minor proportion of rock crystal and non-quartz, excavated from a c. 12m² cliffside trench (TR2), located at the point of a substantial erosion scar, with an eroded pathway running over the excavated area. Quartz artefacts were visible on the surface of TR2 before excavation, with the thin layer of turf/peat having been eroded away along the thoroughfare. The date range of the excavations shows intermittent activity for over two thousand years, from the Later Mesolithic to the end of the Neolithic, resulting in three main artefact-bearing contexts.

The lower, earlier, main artefact-bearing context (C.203) dated to c. 4300-4500 cal BC, accounted for nearly half of the artefacts, and is interpreted as a pre-peat woodland topsoil that was subsequently compressed, truncated, or eroded. The analysis suggests that C.203 represents an area of in situ knapping with a clear demarcation of artefact quantities, types and sizes into three areas – concentration, adjacent, and periphery. This division possibly suggests the working and deposition by the communities of practice of cores and heavy debitage in the adjacent area or a clearance of the larger and heavier artefacts from the concentration into the adjacent area; an above average proportion of the diagnostic types came from the concentration. There appears to be a low proportion of cores from this context for the amount of debitage present, which may imply that not all the cores were deposited in situ. Other cores did not match the debitage and were knapped with a different strategy and on different quartz than available locally, suggesting that these cores may represent an importation of cores by the communities of practice which were not further reduced in situ but instead deposited. Additionally, the non-quartz assemblage from the C.203 group contained cores without matching debitage, again suggesting the deposition of cores in the excavated area but not in situ knapping.

The next main artefact-bearing context was C.206, dated to c. 4000-4200 cal BC. The artefacts from C.206 came from within and on top of the formal, flat, metalled layer of pebbles and cobbles. The construction of the metalled layer marks this context out as the greatest difference from the previous context. Unlike the previous context, there is less of a distinct concentration/adjacent/periphery divide, with a more even spread of material across the top half (northeast), and the lower quarter (southwest) having substantially less.

C.202, the third main artefact-bearing context, may represent a later disturbance, with artefacts within it representing the upper level of C.206. From the analysis of the vein quartz artefacts’ fragmentation and size, however, it does not appear that C.202 contains more fragmented artefacts than C.206, but rather C.206 contained a greater proportion of smaller fragments than C.202 or C.203; C.202 contained more complete and lateral fragments (more likely to be knapping breaks than post-depositional breaks) than C.206, suggesting a lack of disturbance in C.202. While C.202 had a greater proportion of bipolar cores, pointing to a possible Neolithic component in the assemblage, the direct percussion artefacts do not appear to be significantly different from the earlier contexts in terms of the chaîne opératoires, such as noted in the Thornhill Neolithic assemblage. Furthermore, while a considerable proportion of the cores from C.202 were bipolar, there is little evidence of in situ knapping, with just one bipolar flake noted. This may suggest that during the Neolithic material was deposited onto a previous collection of quartz artefacts.

The Thornhill palisaded enclosure sits on a terrace on a low ridge on the left bank of the River Foyle close to the present-day river’s mouth. The development-led rescue excavation was initiated after monitoring of topsoil stripping uncovered substantial archaeological evidence. The site was divided into three areas – Area 1 consisted mainly of 35 pits and was interpreted by the excavators as an area set aside for ritual activity. Area 2 contained eight palisades, five structures, numerous pits, as well as other features. A number of the pits from Area 2 were also interpreted as ritual pits, including a number that blocked the palisade entrances. Area 3 was not fully excavated but the limited investigation suggested further evidence for structures and palisades and other features. The flaked stone assemblage consisted of over 800 vein quartz artefacts, with a minor amount of rock crystal and over 600 flint artefacts, excavated from over 2000m²; the quartz artefacts came from over 50 individual contexts and over 100 fills, as well as 28 strata. 60% of the artefacts came from the topsoil and 18% came from the pits, with the remaining contexts, primarily the palisades and structures, having 8% or less each. None of the contexts appear to represent a knapping floor, suggesting that limited knapping may have taken place within the area excavated, which was only a limited part of the overall settlement.

Three of the five structures contained quartz artefacts. Along with the pits, the structures were over-represented in the proportion of complete flakes compared to other contexts. The deposition of lithics in the Thornhill structures point to differences in the lithic chaîne opératoires between structures and materials – while Structure E contained the largest quantity of non-quartz flaked artefacts, it contained no quartz artefacts and no natural quartz pieces; Structure D contained no non-quartz and contained one quartz flake fragment along with one natural quartz piece. While Structure B and Structure C’s plans intermixed, no quartz was retrieved from Structure C and Structure B had quartz deposition, often of single artefacts, in the foundation trenches as well as under the threshold stone and internal features. Structure B’s (and Structure A’s) artefacts had a greater emphasis of bipolar cores and flakes compared to the pits. However, the deposition of the cores in the structures does not appear to represent knapping taking place, but rather the deposition of cores in the various features such as the foundation trenches.

Of the 35 pits in Area 1, quartz artefacts were uncovered from 10 with another six pits containing natural quartz only. 17 pits in Area 2 contained quartz artefacts. The contexts (apart from the topsoil) with the largest collection of artefacts were two pits. Pit C.2966 in Area 2 contained the largest collection, while Pit C.140 in Area 1 contained the second largest collection of artefacts and largest collection of diagnostic types – half of the artefacts from Area 1’s 10 pits came from this one pit. While the 10 artefact-bearing pits from Area 1 had a greater ratio of quartz artefacts to natural quartz pieces compared to the pits in Area 2, Area 2 had more pits with only artefacts and no natural quartz, and Area 1 had more pits with only natural quartz. Overall, the pits were over-represented in the proportion of diagnostic types and in the proportion of sugar/smooth- or sugar-grained artefacts compared to other contexts. At Thornhill, there appears to be the purposive deposition by the communities of practice of complete quartz flakes in the pits and structures, of a material that has a much higher fragmentation rate than other knapped stone.

As well as this deposition of complete flakes, many of the pits had depositions of complete pebbles and lumps of natural quartz along with lesser quantities of split pebbles and fragments of lumps. These do not appear to represent a caching of lithic raw material, and some pits contain only natural pieces in basal layers, with upper layers containing a mixture of natural and artefactual material. This suggests a structuring of deposits in some pits. The presence of an abundance of ‘natural’ quartz in various pits either with ‘artefacts’ or alone raises the question of the archaeological definition of  natural. For the present analysis, which is examining the use of quartz in the lithic technologies, it is easy to define ‘natural’ as material that does not show signs of use or modification and ‘artefacts’ as those that do. Clearly, the pits suggest that in terms of prehistoric practice such a designation breaks down. While these natural quartz pieces are not artefacts sensu stricto, they represent a clear manipulation of materials that goes beyond the use of quartz for ‘stone tools’. The fact that this manipulation is not observed with ‘natural’ flint adds weight to the argument that quartz had its own significance for the prehistoric communities.

In addition to the significance of ‘natural’ quartz a number of indeterminate pieces suggest the deposition of  antique’ artefacts or as items that looked like artefacts. Four of them came from Structure B. Three, which all resembled cores, came from  a posthole which terminated the southern side foundation trench of Structure B and were deposited with a complete bipolar core, while the fourth, which also resembled a core, and came from an internal porch, deposited with a bipolar flake. A further two indeterminate pieces were interpreted as possible ‘antique’ artefacts – Pit C.138 in Area 1 and Pit C.784 (part of the conjoined ritual pit group blocking a palisade entrance) both contained an indeterminate piece each, that were possible retouched artefacts.

At Thornhill, there is evidence that the communities were working quartz in a similar fashion to flint, but they nevertheless appear to have used and treated the material in different ways. While 60% of the assemblage was found in the topsoil and no clear knapping floor was detected, deposits in the structures and pits can be seen as ritualised activity in the communities of practice’s chaîne opératoires, resulting in structured deposits. At the time of the occupation of Thornhill, Neolithic communities were involved in the construction and use of megalithic structures, many of which have evidence for the use of quartz in various manners. As was argued in relation to the Belderrig quartz scatter, where the analysis of the quartz artefacts did not clearly identify any ritualised or symbolic use or deposition of the material, the quartz from both places can be interpreted as having held differing roles and differing significance depending on the context and on the observer or participant. Consequently, it is not a question of an either/or of the sacred and profane, but rather when, where, and by whom.

While the use of all materials can be seen as symbolically charged, quartz has been argued to be especially powerful material, and this has implications for the interpretation of the assemblages here. Looking at the chaîne opératoires at play from the perspective of a ritualised taskscape places the question of what the ‘tools’ were used for, and what the excavated area represents, in another dimension: in viewing the quartz assemblage as neither strictly utilitarian nor strictly symbolic, one can consider the material as on a continuum of ritualised practice. The quartz used by the communities was not a material found ‘out there’ in the landscape, and subsequently exploited and discarded, but the quartz itself was part of the taskscape amongst the other parts such as the humans, plants, and animals. At Belderrig, it is posited that quarried veins may have been revisited and reworked over the generations, becoming a part of the dynamic traditionalism of the communities. At Thornhill, while most of the assemblage appears to be cobble-based, quarrying may also have taken place. Cooney (1995) has pointed to ritualised activity at a Neolithic porphyry axe quarry site where a cluster of quartz artefacts were deposited at the base of the quarried rock face.

At Belderrig, while no structured deposition in features was noted, the clearest representation of symbolic or ritualised practice can be seen in contrasts – a small number of cores have been interpreted as being non-local quartz; these cores had no matching debitage, suggesting an importation of cores for deposition at the locale. As well as these non-local quartz cores, the chaîne opératoires included the deposition of non-local, non-quartz cores and debitage; these cores and debitage were a mismatch of materials, suggesting no in situ knapping, but rather the deposition of non-local material. One of the non-quartz artefacts deposited was a chert flake with a triangular – almost flake-shaped – quartz inclusion thus marrying the local and non-local materials. This mismatch of materials – both quartz and non-quartz – could be interpreted as the excavated area representing a ‘dump’, a midden of lithics and organic material, with the lithics being the remaining material culture. However, it was argued that the material does not necessarily represent a dumping of material – a midden sensu stricto (for discussions on middens and refuse see Needham and Spence 1997) – but rather can be seen in line with the structured depositing of the local quartz, of activities taking place in the context of a midden sensu lato, where a midden can be seen as an accumulation of material culture, an accumulation of artefacts and ecofacts, without modern categorisations of these as rubbish or waste.

11.5 Conclusion

This thesis undertook a series of experiments in order to develop a framework for analysing quartz technology in Irish prehistory. The results of the experimental knapping, the experimental burning, and the quartz recognition experiment have shown that the analysis of vein quartz artefacts is certainly difficult, but not impossible – a clear understanding of the fracture mechanics of the material as set out in the experimental knapping provides a framework for the analysis of vein quartz in the archaeological assemblages, and therefore helps in understanding the prehistoric communities who chose to use this material. While the fracture mechanics of quartz created constraints to its use – as witnessed by the lack of certain tool types made with cryptocrystalline materials – quartz should not be interpreted as a second, or third, rate material. Rather, quartz is a special material with special qualities which the prehistoric communities of practice throughout Ireland understood and used successfully.

By way of conclusion, I will set out a summary of the quartz analysis framework developed and used in this project, and reiterate why such a framework is necessary. The significant differences between quartz and chert (and other cryptocrystalline materials) fracturing necessitates a quartz framework. As summarised in Table 11-1, assemblages of chert and quartz knapped using the same technique will appear to be substantially different in terms of debitage types, fragmentation, morphology, and occurrence of attributes such as bulbs, compression rings, and eraillure flakes. If mixed assemblages are to be analysed correctly these differences must be factored into the analysis, otherwise interpretations will be misleading.

The initial part of the framework consists of dividing the material into ‘worked’ and ‘natural’ quartz. Pieces with sub-rounded or rounded edges are considered ‘natural’ quartz; angular pieces may also be natural fragments, and some of these may be incorrectly categorised as ‘debris’ – it can be difficult to draw a clear, distinct line between them. As noted in the analysis of the Thornhill assemblage, even though many of the quartz pieces were deemed ‘natural’, there appears to have been distinct depositional practices of ‘natural’ quartz by the communities there. Consequently, even though pieces may be deemed natural in terms of stone tool analysis, this does not mean that they were not in fact used in prehistory.

The lynchpin of the framework is the fragmentation characteristics of quartz. On average, the quartz debitage produced 4.5 times more ≥10mm fragments that chert, with relatively few complete quartz flakes produced. It is critical that analyses differentiate between complete and fragment flakes. As noted previously, in his analysis of numerous Scottish quartz assemblages, Ballin (2008) made no reference to flake fragments, with the result that it is unclear if all flakes were being treated as if they were complete, or if the analysis treated both complete and fragment flakes equally. The framework developed here categorised the break and fragment types (Figure 6‑7), which provided a detailed analysis of the artefacts, with which to compare to the archaeological assemblages. Common occurrences were the sequential breaks and fragments, which were amongst the hardest to identify in the experimental assemblage, and were generally interpreted as ‘debris’. Because of the difficulty in identifying these breaks and fragments consistently, these categories were excluded during the analysis of the archaeological material, inevitably resulting in a loss of information and an increase in the ‘debris’ category.

For the analysis of cores, the process of core fragmentation complicates the interpretation of assemblages, as many of the core fragments are indistinguishable as such, possibly resulting in an under-recognition of cores in archaeological assemblages and a consequent over-count of debitage. The bipolar core assemblage produced a greater proportion of core fragments, but the bipolar component is, overall, easier to identify as bipolar cores and bipolar core fragments – however, the participants of the quartz recognition experiment had significant difficulties in identifying bipolar cores. One difference noted to Knutsson’s experimental dataset was the occurrence of conical pieces, which he states as occurring from both bipolar and direct percussion knapping. In this series of experiments, all the conical pieces resulted from bipolar reduction, and are treated, cautiously, as bipolar core fragments.

In terms of attributes of flake platforms, the following points are provided.

1. Impact point. The impact point on quartz is typified by a whitened area, formed by micro- and macro-fractures which increase the opacity in the area and also partially fill with quartz dust; the whitened impact point is found on the detached flake’s platform and often on the core if the impact point was at the edge of the platform. However, the impact point may be more ephemeral in many cases and in some case not visible at all – while the vast majority of the complete hard hammer and bipolar flakes retained a visible impact point, the soft hammer had a significantly lesser proportion. The lack of a whitened area with some of the soft hammer platforms is a result of a lack of micro-fractures and macro-fractures forming.

2. Platform morphology and radial and transverse fissures. Radial and transverse fissures form on the platform, which can result in full fractures if they develop significantly. As well as these fissures, more substantial fractures can develop, with a signature fracture being the triangular fracture with the triangle’s apex forming at the impact point; another triangular fracture can often form radiating towards the dorsal face of the platform as well. The triangle’s apex is often less acute, resulting in a more rounded form and appearing as a convex fracture. If these fractures develop fully, a triangular-shaped platform fragment is formed, or a more convex shape if the apex was less acute. Another characteristic platform is formed during a sequential break, where the flake breaks into a number of flakes, which some or all can take the appearance of complete flakes, with complete platforms and flake terminations. The bipolar flake platforms are generally characterised by a rounded platform with the steep side on the ventral face of the flake, with the platform angle reversed compared with direct percussion platforms. As with the direct percussion platforms, bipolar platforms can also fracture in a triangular fashion, leading to triangular-shaped platform fragments. While non-proximal radial fissures are a consistent pattern on the quartz, these fissures occur regularly on non-knapped quartz and therefore are not by themselves indicative of knapped quartz.

3. Pseudo-platforms. A complicating fragment is where a pseudo-platform is created by a transverse break, formed by edge damage during flake formation – these ‘platforms’ appear to have an impact point and radial fissures, and can appear to be complete flakes rather than non-proximal flake fragments.

4. Bulbs and compression rings. For both bipolar and direct percussion, bulbs formed very infrequently and barely any compression rings were discernable.

5. Distinction between bipolar flakes and platform flakes. While this distinction was generally clear, a sizable proportion of bipolar flakes appeared as platform flakes. 17.1% of the ≥10mm bipolar debitage and 22.6% of the bipolar flakes appeared to be platform flakes, while 2.6% of the ≥10mm platform debitage and 4.6% of the platform flakes appeared as bipolar flakes. This highlights that it is more likely that bipolar flakes will be underestimated in an assemblage compared to platform flakes.

The experimental knapping highlighted that nearly half of a quartz assemblage’s ≥10mm debitage may be debris, but the majority of these will be <20mm (greatest dimension). However, in order to attain a greater depth of analysis, this framework sub-divided the debris into size categories, with ‘slivers’ being debris with a thickness of <3mm – the 3mm cut-off point was decided upon after experimentation suggested that it created a meaningful division. The pieces were passed through a callipers set to 3mm, allowing for a rapid categorisation of the pieces. This proved an efficient method of categorising artefacts. The <10mm debitage was not classified as flake fragments, instead these pieces were classified as debris. While this categorisation will inevitably miss some small flake fragments, this system attempted to strike a balance between a thorough analysis and limited time period with which to analyse an assemblage; these small fragments are the hardest – and most time consuming – to identify flake attributes on, therefore the time spent on classifying these small pieces can often be of limited value.

[29]Excluding possible cores.[return]

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