The application and misapplication of mass analysis in lithic debitage studies

The technique of debitage mass analysis based upon size grades of debitage populations is shown to be prone to errors when making interpretations about the kind of tool produced or the kind of lithic reduction technology used. Significant sources of error may originate from differences in individual flintknapping styles and techniques, raw material size and shape variants, and mixing of debitage from more than one reduction episode. These sources of error render debitage Mass Analysis ineffective for determining the kind of stone tool reduction activities practiced at excavated sites. Mass Analysis may be effective for determining artifact reduction sequences if it is used on debitage from a single reduction episode or part of a reduction episode. However, it is shown that Mass Analysis when used for assessing reduction sequence information, must also control for the effects of raw material variability, assemblage mixing, and flintknapping styles.     

The role of abrasives in the formation of lithic use-wear

This paper briefly examines the question of the influence of abrasive particles on the development of use-wear on stone tools. It is argued that grit inclusions may have been a common element of prehistoric tool using conditions, hence the need for archaeological experiments which consider this variable. A series of experiments are described where end-scrapers were used on bone and hide surfaces both with and without a grit inclusion. The resulting wear patterns are discussed and illustrated. It is concluded that the addition of grit to the worked surface causes a dramatic and demonstrable change in use-wear development.     

Swept under the rug: the problem of unacknowledged ambiguity in lithic residue identification

Microscopic analysis of organic residues on stone tools is used to interpret prehistoric stone tool functions. The morphology of some residues can be difficult to interpret, yet this ambiguity is rarely acknowledged in the literature. Our research seeks to understand the nature of this ambiguity by objectively identifying ambiguous residues in our reference collection. We trained four archaeologists in residue analysis using one part of our reference collection, then tested their ability to identify sixty-eight residues in another part of the same collection. Forty-eight of the residues in the test (70%) were correctly identified by three or all four subjects. We considered the remaining twenty residues, which were correctly identified by two or fewer of the subjects, to be ambiguous. These are most often in the hide-scraping, bone-scraping, and hardwood-scraping (macerated) categories, and tend to have an atypical morphology which falls in the range of variability of another residue category. Some of these residues also have optical properties which make them more difficult to image than others. We explore the potential for scanning electron microscopy (SEM) to improve residue identification in a second test. This test shows a modest improvement in identification success rates of ambiguous residues when SEM images are included. We conclude that while images from different types of microscopes can improve reliability of identification, some residues will always be ambiguous. Rather than being ignored, these ambiguities should be brought to light, closely examined, and published as such.     

Variability in bifacial technology at Elandsfontein,Western cape,South Africa: a geometric morphometric approach

This study applies a new three-dimensional measurement technique to determine the major source of variation in the Acheulian bifacial tool collection from the Middle Pleistocene site of Elandsfontein, South Africa. This three-dimensional technique is compared with conventional two-dimensional methods to investigate which methods capture morphological variation in the assemblage most comprehensively. Additionally, a set of experimentally produced bifacial tools are incorporated into the analyses to isolate the behavioral pattern underpinning identified variation in the archaeological assemblage. The interpretative breadth of current models explaining morphological variation in bifacial tools is then tested against the pattern identified in the Elandsfontein assemblage. Variation appears to be related to the consistent application of a specific reduction strategy associated with the early stages of bifacial tool manufacture. The intensity with which this strategy was applied seems to have been mediated by the availability of raw material that was suitable for the production of large bifacial tools.     

A biface and blade core efficiency experiment: implications for Early Paleoindian technological organization

Early Paleoindians often are described as highly mobile hunter–gatherers who employed lithic technologies designed to minimize stone transport costs. We experimentally reduced blade and bifacial cores and found both reduction strategies to be equally efficient for the production of useable flake blanks. Further, when compared to similar core reduction experiments, the results of this study showed no significant differences in core efficiency between bifacial, prismatic blade, and wedge-shaped blade core reduction. Biface and blade cores with initial weights greater than 1000 g produced useable flakes as efficiently as informal cores. However, bifacial and blade core efficiency decreased with initial core weight. When considered in terms of Early Paleoindian technological organization, differences in core efficiencies suggest that Folsom groups employed core reduction strategies designed to minimize stone transport costs, but Clovis groups did not.     

The application of 3D laser scanning technology to the assessment of ordinal and mechanical cortex quantification in lithic analysis

Recent studies make use of cortex proportion as a proxy measurement for the impact of artefact transport on assemblage formation. Cortex in these studies is measured on an ordinal scale and analysed in relation to mechanical measurements of artefact size. Here we report on the use of a 3D laser scanner to obtain precise measurements from experimental lithic reduction sets. High-resolution measurements of cortex area are compared to measurements obtained through ordinal approximations of cortex proportion and mechanical approximations of artefact size. While the ordinal and mechanical measurements result in considerable error for individual artefacts, estimates improve significantly as sample size increases.     

Vein quartz in lithic traditions: an analysis based on experimental archaeology

Worldwide, vein quartz was a commonly used raw material for stone tools but this material has proved difficult for archaeologists to analyse because many quartz assemblages appear to be comprised of amorphous pieces, not easily recognised as humanly modified or forming ‘tools’. This paper discusses the analysis of the debitage – focusing on the debitage fragmentation rate, the debitage, break, and fragment types, and the quantitative analysis of the complete flakes – resulting from experimental knapping of quartz, which formed part of a project which investigated the use of quartz in Irish prehistoric lithic traditions. The results have highlighted the complexity involved in analysing quartz assemblages, and the significant differences between the debitage products of quartz and chert knapping assemblages. While bipolar knapping is generally easy to differentiate from direct percussion, it is harder to differentiate between soft and hard hammer percussion.     

Explaining the monopoly in shell-bead production on the Channel Islands: drilling experiments with four lithic raw materials

Significant political and economic developments among the Chumash of southern California were catalyzed in part by the emergence of an intensive, specialist-driven shell-bead industry during the second millennium CE on the Santa Barbara Channel Islands. The production of millions of beads depended in turn on the availability of lithic microdrills of standardized form and materials. Channel Islanders quarried a particular stone type, a blocky Monterey Formation chert, from multiple outcrops situated close to the eastern shores of Santa Cruz Island. Rich archaeological assemblages document the lithic and shell byproducts of these intertwined production systems, each of which endured for several centuries (CE 1150–1819). Islanders invariably chose Island chert for making microdrills: hundreds of thousands of specimens recorded to date are of this material. Furthermore, nearly every microlith in all of Chumash territory (post CE 1150) was produced on the islands; the large populations on the mainland did not participate in microlith making or bead making after CE 1150–1200. We argue that this pattern had its roots not only in the patchiness of key resources and shifting regional social relationships, but also in the physical properties of available raw materials. Here we experimentally assess the properties of Santa Cruz Island chert alongside three important mainland raw materials—Grimes Canyon fused shale, Coso obsidian, and Vandenberg chert—that potentially could have been tapped to make microliths. We test the proposition that Island chert outperforms other lithic materials in drilling efficiency and drill use life. Our experimental results from 108 drilling trials reveal sharp distinctions in performance characteristics across the four materials. We infer that the process by which Islanders became the more-or-less exclusive manufacturers of shell-bead currency in southern California was facilitated by both the efficacy and physical properties of the Island cherts and the propitious locations of the outcrops.     

Experimental evidence for lithic projectile injuries: improving identification of an under-recognised phenomenon

Between the Upper Palaeolithic and the spread of metallurgy stone-tipped projectiles were of great importance both for subsistence and as weapons. Whilst finds of embedded projectile points in human and animal bone are not uncommon, identifications of such wounds in the absence of embedded points are rare. Previous experimentation involving archaic projectiles has not examined the effects of stone-tipped projectiles on bone. This paper presents the results of experiments in which samples of animal bone were impacted with flint-tipped arrows. The results demonstrate that positive identifications can be made, both grossly and microscopically, of bony trauma caused by flint projectiles. In addition, flint projectiles are shown to often leave small embedded fragments, which can also be identified microscopically. These results compare well with archaeological examples of suspected ‘arrow wounds’ and the article demonstrates the practical application of this data in identifying such injuries. By facilitating the recognition of projectile trauma these findings will have significance both for the investigation of hunting strategies and levels of conflict amongst early human societies.     

Oldowan reduction sequences: methodological considerations

Transport of resources is a major feature of Oldowan hominin technological adaptations. Comparisons between different Oldowan localities often employ measures of transport that are based on artefact attributes as proxies for the intensity of raw material utilization. The Technological Flake Category system [Toth, N., 1985. Oldowan reassessed: a close look at early stone artifacts, Journal of Archaeological Science 12, pp. 101–120] has been used extensively to infer the relative intensity of lithic reduction within Oldowan assemblages. Here we use a large experimental sample to test the relationship between a flake's stage in a reduction sequence and various quantitative attributes. We demonstrate how many previously described attributes are affected by initial core size. We then develop a multiple linear regression model that incorporates several variables to predict the placement of a flake within a generalized reduction sequence. The model is then applied to Oldowan assemblages in the Koobi Fora Formation which explores the strengths and weaknesses of different methods of investigating reduction intensity on an assemblage level.     

Introducing a new experimental design for controlled studies of flake formation: results for exterior platform angle,platform depth,angle of blow,velocity, and force

Potential variables that underlie variation in flake size, and in some instances shape, are investigated in a newly designed experiment. This new design, which utilizes glass cores molded to a specific shape, results in flakes that are identical to archaeological ones. Variation in exterior platform angle, platform depth and angle of blow all directly affect flake size, and in the case of exterior platform angle, flake shape as well (in spite of constant core surface morphology). In treating velocity and force independently, neither is found to affect flake size or shape. These results have implications for understanding different strategies that flintknappers may employ to control the size of their flake products.     

How flakes shatter: a critical evaluation of quartz fracture analysis

Despite its worldwide use as a stone tool raw material, quartz is known to be a difficult material for archaeologists. The main reason for this is the tendency of quartz flakes to fragment during detachment, which complicates the use of traditional lithic analyses. In this article we present an experimental study of quartz flake fragmentation. We evaluate the method called fracture analysis that has been developed and used explicitly for the study of quartz assemblages. The method assumes high predictability of quartz flake fragmentation, but our experiments show that there is significant variation in fragmentation that fracture analysis does not take into account. Our results indicate that this variation is partly explained by indenter hardness, the relative thickness of the detached flake, as well as individual knapper-related factors. These results undermine the applicability of quartz fracture analysis in its current form. In addition, we discuss the effects of flake fragmentation on the technological organisation of prehistoric quartz users and suggest that it has affected reduction strategies as well as blank and tool dimensions. We also suggest that there should be mobility-related differences in archaeological assemblages in terms of the quality of the quartz raw material and that the curation of quartz should be low in relation to better quality raw materials used parallel with it.     

Particle size distribution of lithic assemblages and taphonomy of Palaeolithic sites

Lithic debris derived from knapping and used tools can be assimilated to simple sedimentary particles that may undergo size sorting when exposed to geomorphic processes such as streamflow or overland flow. Sorting can be identified by comparing the size distribution of archaeological assemblages to that of experimental core reduction sequences. A new database including different types of raw material (mainly flint and quartzite) and Palaeolithic debitage (blade, Levallois, discoid, on anvil, and shaping) has been built for this purpose. Palaeoeskimo data have also been added to illustrate microlithic industries. For all the debitages and raw materials, the particle size of knapping products >2 mm in width fits with a power-law distribution and shows only minor fluctuations, the range of which is always <15% between experiments (all steps of the chaîne opératoire included up to the final tool). A lithic assemblage derived from block/core knapping or blank/preform production will display a particle size distribution close to the experimental distributions if not subsequently modified. Modifications may originate either from sedimentary processes or from anthropogenic factors. To help distinguishing amongst these, data on the impact of both water flows on sedimentary particles or experimental assemblages, and anthropogenic processes such as importation-exportation (of core, preforms or finished tools) or uneven spatial distribution of the different steps in core reduction and tool production within a site, are reviewed. By contrast to anthropogenic modifications, sedimentary processes are generally typified by strong impoverishment in or selective accumulation of fine-grained (<10 mm) artefacts together with a low intra-site variability (spatial homogenization) or a downslope size trend. Archaeological case studies taken from French Palaeolithic site are then detailed. Evidence for lithic redistribution implies that care should be taken in archaeological site analysis since sorting may impact significantly the initial techno-typological balance of the assemblage.     

Estimating original flake mass from 3D scans of platform area

This study confirms the increased capacity to predict flake mass that arises from more accurately measuring surface area in three dimensions using a digital scanner. We also reveal the existence of significantly different relationships between platform area and flake mass for flakes with different platform types and ventral and dorsal morphologies. These different relationships between platform surface area and mass have not been previously identified, and reveal the complexity of platform/mass relationships. Using multivariate regression of 3D platform surface area and external platform angle we improve the accuracy of predictions of original flake mass. We propose a method for studying reduction intensity on retouched flakes, based on comparing predictions of the initial mass of the flake with measurements of the mass following retouching to estimate the amount of mass removed through retouching. We name this approach the Initial-/Terminal-Mass Comparison, or ITMC. Our experiments demonstrate that the capacity of the 3D platform scans to predict flake mass, and by implication the capacity of the ITMC to estimate mass loss, rivals or exceeds the capacity demonstrated for existing reduction measures.     

Establishing discovery probabilities of lithic artefacts in Palaeolithic and Mesolithic sites with core sampling

This paper reports the results of a study into the effectiveness of core sampling for discovering Palaeolithic and Mesolithic hunter-gatherer sites in the Netherlands and northwestern Belgium. Earlier work established optimal sampling strategies for use in archaeological heritage management survey in the Netherlands. However, the statistical model used for this was based on a limited amount of data on the distribution of lithic artefacts in Palaeolithic and Mesolithic sites. For the current study we have analyzed the distribution of artefacts in a selected number of excavated sites, and estimated discovery probabilities of these sites through simulation. The simulation results indicate that discovery probabilities are lower than expected due to the effect of clustering of finds. Furthermore, the density of flints in Palaeolithic and Mesolithic sites is generally lower than the estimates that were used for setting up the optimal sampling strategies, and a substantial number of sites is very small. This means that, in order to discover Palaeolithic and Mesolithic sites with sufficient reliability, we will have to apply more intensive survey strategies than have been recommended up to now.     

New experimental evidence on the relation between percussion flaking and flake variation

Controlled experiments in percussion flaking allowed for objective analysis of relationships between variables of flake production and those variables which are attributes of the final result. The independent variables, those controlled by the flintknapper in the production of stone tools, include force and angle of blow, platform thickness and exterior platform angle. The dependent variables are those attributes of the flakes which are often used in current lithic analyses and include interior platform angle, length, thickness and flake termination. The results clearly show that exterior platform angle is highly significant for understanding many aspects of flake production. These and other relationships between the independent and dependent variables are also discussed.     

The relative effects of core surface morphology on flake shape and other attributes

It is long been thought that many flake attributes, including both size and shape, are largely due to the morphology of a core’s flaking surface, yet this has never been tested under strictly controlled conditions. Using molded glass cores with surface morphologies that highly resemble prehistoric ones, this experiment demonstrates that while core surface morphology does exhibit some influence on flake size and shape, a high degree of variation in flakes produced with the same core surface morphology shows that the effects of other independent variables, such as exterior platform angle and platform depth, have an even stronger effect. A major implication of these results is that current approaches to reconstruct prehistoric knapping strategies are overlooking significant sources of variation.     

Experimental use and quantitative performance analysis of triangular flakes (Levallois points) used as arrowheads

The invention and widespread use of projectile weaponry is a characteristic presumed to exist only with Homo sapiens. However, as finds of wooden material during the early development of projectile weapons are extremely rare, this remains a contentious topic. Recent work has proposed a series of ballistically-significant morphological characteristics of stone points that yield information about their potential use. Here we report on initial experimental approaches to quantifying the performance of relatively simple stone points as arrow armatures. Two experimental trials were performed using a series of 51 Levallois points. The first, against a uniform density target, was designed to give an overall indication of performance. The second, against a simulated animal carcass, demonstrated the durability of these points. The results of this study suggest that small Levallois points could have functioned as arrowheads, albeit ones likely to break after limited use. They also suggest that these points’ penetrating power is strongly controlled by their morphometric characteristics, most notably their perimeter. This latter finding refines a method for assessing hypothetical Paleolithic stone points on the basis of tip cross-sectional area previously proposed by others.     

Mobility patterns and core technologies in the Middle Paleolithic of the Levant

Mobility is thought to be a significant source of Middle Paleolithic archaeological variability in the East Mediterranean Levant. However, models of Levantine Middle Paleolithic land-use have historically been based on rare and taphonomically sensitive evidence from a limited number of sites. Because lithic artifacts are the most ubiquitous archaeological remains available to the prehistorian, relationships between stone tool technology and mobility patterns can improve tests of hypotheses about prehistoric land-use strategies. This paper examines variation in Middle Paleolithic mobility strategies in the Levant from the perspective of core technology. A model linking expedient core reduction techniques and decreased mobility is adapted from one developed for late prehistoric contexts in the New World. Incorporating core data from numerous Levantine Middle Paleolithic assemblages, this study tests hypotheses about diachronic change, synchronic geographic variation, and possible hominin behavioral differences in mobility strategies.