Lithic Reduction Research Articles

An empirical test of the relative frequency of bipolar reduction in Beds VI, V, and III at Mumba Rockshelter, Tanzania: implications for the East African Middle to Late Stone Age transition

Mumba Rockshelter, Tanzania, is the only East African site spanning a continuous record of more than 100,000 years, including the Middle Stone Age (MSA) to Late Stone Age (LSA) Transition. Rather than examine the presence or absence of traditional markers of “behavioral modernity”, we have endeavored here to respond to the calls of Shea (2011) and Basell (2008) by examining the proportional similarity of a trait present throughout the MSA–LSA sequence at Mumba Rockshelter: the bipolar technique of lithic reduction. We use a quantified, experimentally derived proxy to track the relative amount of bipolar percussion among Mumba's Beds VI, V, and III, namely, waste shatter. Our examination of Mehlman's previously unanalyzed collections from Mumba demonstrates that in terms of bipolar production Bed V is statistically indistinguishable from the Late Stone Age (LSA) Bed III, but significantly different from the Middle Stone Age (MSA) Bed VI. Given that Bed V dates to 56.9 ± 4.8 − 49.1 ± 4.3 ka cal BP, this result is consistent with other evidence that the origins of the LSA in East Africa began well before 40 kya, and that Mumba Bed V represents one of the earliest manifestations of the LSA in East Africa. We conclude with a discussion of factors that may have influenced the increased dependence of bipolar production at the site.

The Hogeye Clovis cache, Texas: quantifying lithic reduction signatures

The Hogeye Clovis cache is comprised of 52 late-stage bifaces, finished points, and knife/cores cached in central Texas. Because these artifacts were all likely made and cached approximately 13,000 years ago by one or a handful of knappers belonging to a single band with a shared Clovis cultural template, Hogeye provides a rare opportunity to investigate Clovis lithic reduction signatures. This paper builds on previous analyses and presents new methods for quantifying Clovis biface production signatures, including serial flaking and the timing of last overshot flaking. The results show that the Hogeye cache bifaces technologically and morphologically differ from other regional Clovis biface reduction signatures. Additional data is needed to determine whether these differences reflect individual knapping preferences or regional cultural signatures. The methods used and developed here are not Clovis-specific and could be modified and combined with other analytical techniques to identify reduction signatures in biface assemblages from other times and places.

Materials and Corrosion 3/2012

Cover: Grinding surface pattern of steel, coated with thick‐film E‐coat (40 μm) after a stone chipping defect exposed in an accelerated corrosion test (BMW AA‐0224) showing blistering and a corrosion progress. The small image represents a cross section of the sample which was carried out on the FEI Nanolab Nova200 dual‐beam focused ion beam (DB‐FIB – FEI company, Eindhoven, The Netherlands). For the single wide cut (1350 μm by 30 μm) a beam current of 20nA at an acceleration voltage of 20kV was used. Afterwards the part in front of the cross section was removed manually with a scalpel blade. Additional ion beam cross section cleaning with 7nA at 20kV was performed and images were taken with the electron beam using the Everhart‐Thornley detector at 52° tilt angle and an acceleration voltage of 5kV.Grinding surface pattern and analyzes were investigated at the Austrian Centre for Electron Microscopy and Nanoanalysis (ZFE‐Graz), Graz‐Austria, by Dr. J. Wagner.More detailed information can be found in: A. Schönberger, S. Virtanen, V. Giese, H. Schröttner, C. Spießberger, Non‐destructive detection of corrosion applied to steel and galvanized steel coated with organic paints by the pulsed phase thermography, Materials and Corrosion 2012, 63, 195.

Records of human occupation from Pleistocene river terrace and aeolian sediments in the Arneiro depression (Lower Tejo River, central eastern Portugal)

In the uppermost reach of the Lower Tejo River (eastern central Portugal), where the river crosses two quartzite ridges that separate the Ródão (upstream) and Arneiro (downstream) depressions, Palaeolithic artefacts have been recovered from three lower river terrace levels and a cover unit of aeolian sands. This paper presents data on the discovery of archaeological artefacts from the terrace levels and the aeolian sands that can be linked to Middle and Upper Palaeolithic industries from new field sites at Tapada do Montinho and Castelejo. The archaeological data when placed in a geomorphological, sedimentary and chronological framework, contribute new information on the understanding of human occupation in western Iberia during cold-climate episodes of the last 62 to 12ka; and especially during the cooler and driest conditions that occurred between 32 and 12ka, when the climate favoured aeolian sediment transport. In the Lower Tejo River, the integration of absolute age datasets with archaeological, geomorphological and sedimentary data indicate that in westernmost Iberia the first appearance of artefacts in river terrace sediments suggests that the earliest marker for human occupation dates from the lower Acheulian (Lower Palaeolithic), probably corresponding to an age of ~340ka. Data also suggest, for the first time, that Acheulian lithic industries were replaced by Middle Palaeolithic ones (namely the Levallois stone knapping technique) by ~160ka (~MIS6). Middle Palaeolithic industries were later replaced by Upper Palaeolithic industries at 32ka. The post 32ka period, dominated by aeolian sediment transport, is related to the onset of cold-dry climate conditions which resulted in low river flow discharges, floodplain exposure and reworking by NW winds. This cold-dry period is coeval with the disappearance of Megafauna and associated Neanderthal communities, and the replacement of the Middle Palaeolithic industries by Upper Palaeolithic ones in this westernmost part of Europe.

Réflexion autour de la fonction des retouchoirs en os de l’Aurignacien ancien

Bone retouchers are the most ancient osseous tools of the European Palaeolithic. They are very frequent on Mousterian sites and persist throughout the Upper Palaeolithic. Several functional analyses have been devoted to them and the most commonly accepted hypothesis proposed is their use for lithic tool retouching by percussion. However, this hypothesis is based mainly on studies of Mousterian pieces while few functional analyses have been undertaken on Upper Palaeolithic bone retouchers. The persistent presence of these “ ad hoc” tools makes their study important. This article presents the results of a techno-functional analysis devoted to the Early Aurignacian bone retouchers from Abri Castanet at Sergeac (Dordogne), northern and southern sectors (layer A and US 131 and below), Grotte des Hyènes at Brassempouy (Landes, complex 2) and Gatzarria at Suhare (Pyrénées-Atlantiques, layer cbcf). These unworked bone tools, including many specimens identified a posteriori among faunal remains, represent a significant part of the studied assemblages’ osseous equipment. There are two categories of retouchers : those on raw bone fragments and those on technical objects. The former, most numerous, are mainly long bone shaft fragments recovered after food operations and used just as they were, without modification. The latter correspond to the use of finished objects like smoothers and awls as well as manufacturing by-products. They bear diagnostic traces of utilisation in the form of linear, deep, short depressions, v-shaped in cross section. These depressions are similar to those that have been described in previous work involving microscopic observation and are compatible with use for lithic tool retouching by percussion. However, unlike Middle Palaeolithic retouchers, where the depressions are perpendicular to the main axis of the piece, Early Aurignacian depressions are often vertical (in combination or not with horizontal ones). This is a characteristic feature of Upper Palaeolithic retouchers related to their positions during use. The vertical depressions imply that the main axis of the retoucher is oriented parallel to the lithic edge during use. Quite obviously, this change in the functioning of retouchers must be linked to changes in flint-knapping processes. To understand this relationship, we explored the effects of changing the orientation of retouchers. One notable difference is their curvature in the transverse and longitudinal axes. The latter is clearly more pronounced than the former, meaning that the retouchers offer a greater overall surface area when used in a parallel orientation. We hypothesized that this orientation was preferred to increase the active surface of retouchers for the retouching of blade products. Indeed, during the Early Aurignacian, the manufacture of blade tools, scrapers in particular, often involved retouching very convex and narrow ends. Orienting the retoucher parallel to the lithic edge would have been a technical solution to compensate for the decrease in the active surface presented by the strong convexity of blade ends. However, within the Early Aurignacian lithic industry, blade ends are not the only items to show strong convexity : the fronts of carinated and nosed scrapers also display them. The use of retouchers in bladelet knapping has not so far been considered, but constitutes a second hypothesis that could explain the particular orientation of Early Aurignacian retouchers during use. T hese two assumptions have been tested by experimental replication. Results show that bone retouchers are effective tools for both blade retouching and bladelet knapping, provided that the weight of the retoucher is adjusted to suit the type of lithic product. In addition, lithic and bone tools produced experimentally fall within the range of variation observed in the archaeological assemblages studied. Finally, although this has not always been necessary, experimentation confirms the usefulness of parallel retoucher orientation to adapt the active surface areas to strong lithic convexity. To date, strong convexity of lithic products is the main factor likely to explain the change in retoucher orientation that occurred at least as early as the Early Aurignacian. Thus, retouchers of this period attest to the duration of an ancient technical process, involving the use of bone for stone knapping. Specimens bearing vertical depressions thus illustrate the adaptation of the retouchers to “ new” lithic technologies. The important role played by retouchers in retouching Mousterian tools and their number within the assemblages studied leave little doubt as to their use in retouching Upper Palaeolithic blade products. However, it is still difficult to determine whether they were in fact used in bladelet knapping. The traces of utilisation on experimental retouchers are quite similar to those on specimens used in blade retouching. An expanded experimental program and analysis of the bone tools with high magnification should facilitate the assessment of morphometric changes in use-wear traces based on activity. In addition, a comparison of technical and functional characteristics of archaeological and experimental lithic products should help clarify the array of hammers used during the Aurignacian.

The New Materials Automotive Electrophoresis Pretreatment - Oxsilan Technology

Oxsilan technology has begun replace the iron and zinc phosphating general industry gradually. Oxsilan technology pre-treatment technology has some advantages such as environmental protection, free of harmful heavy metals, residue-free and low energy consumption, but the domestic automotive pretreatment technology has not yet applied. Through oxsilan technology, this paper carries out cycle test, stone chipping resistance, salt spray test, using cold rolled (CRS), electro-galvanized sheet (EG), hot dip galvanized sheet (HDG) and aluminum (Al) and compares with sample performance of electrophoretic coating of oxsilan technology and phosphate electrophoresis film. The results show that oxsilan technology has potential to replace iron and zinc phosphating technology in the automobile pre-treatment technology.

Non-destructive evaluation of stone-impact damages using Pulsed Phase Thermography

Stone chipping caused specific damages of coating systems, such as delamination, paint loss, or fracture of interlayer, were studied by Pulsed Phase Thermography. The measurement is based on the influence of individual barriers, which are created by defects, on the thermal heat flux. Defective and intact layer systems can be well distinguished, due to the clearly diverse return signals. We moreover demonstrate how the signals can be correlated with specific defects. The main advantages compared with currently used methods are the reliable and improved localization and identification of defects, as well as the significant reduction of measurement time.

The Early Oldowan Stone-Tool Assemblage from Fejej FJ-1A, Ethiopia

Located in the Omo-Turkana basin at the northern limit of the Koobi Fora sedimentary Formation, the Fejej region has recently proven to be a rich study area for understanding early hominin behaviour and paleoenvironmental conditions. Among the rich fossiliferous and stone artefact localities discovered so far at Fejej, the FJ-1a archeological site has yielded a faunal and lithic assemblage in primary context. The archeological level is situated within a 15 meter fluvial sequence beneath a volcanic tuff. Geochronological data from the FJ-1 sequence indicate an age of nearly 1,9 Ma for the FJ-1a artefact level. The stone industry was knapped from locally available raw materials (mainly quartz and basalt) and rocks had been carefully selected according to specific petrographical and formal criterion. Hominins mastered several distinct stone knapping methods and used more or less exhaustive reduction sequences in order to produce small flakes. The different techniques used for stone reduction are defined in this paper thanks to a series of refits of flakes onto cores. Along with the refits, an in-depth analysis of the flakes, cores and worked pebbles provides an overview of the technological capacities of hominins present at the site nearly 2 million years ago. After the Fejej FJ-1a site was abandoned the archeological materials were rapidly buried, leaving an almost undisturbed archeological level. This site appears to represent a short episode of hominin occupation.

Use of stone powder in concrete and mortar as an alternative of sand

Stone powder produced from stone crushing zones appears as a problem for effective disposal. Sand is a common fine aggregate used in construction work as a fine aggregate. In this study, the main concern is to find an alternative of sand. Substitution of normal sand by stone powder will serve both solid waste minimization and waste recovery. The study focuses to determine the relative performance of concrete by using powder sand. From laboratory experiments, it was revealed that concrete made of stone powder and stone chip gained about 15% higher strength than that of the concrete made of normal sand and brick chip. Concrete of stone powder and brick chip gained about 10% higher strength than that of the concrete normal sand and stone chip concrete. The highest compressive strength of mortar found from stone powder which is 33.02 Mpa, shows that better mortar can be prepared by the stone powder. The compressive strength of concrete from stone powder shows 14.76% higher value than that of the concrete made of normal sand. On the other hand, concrete from brick chip and stone powder produce higher compressive value from that of brick chip and normal sand concrete. Key words: Stone powder, concrete, mortar, concrete, compressive strength

Effect of Crushed Clay Brick as Coarse Aggregate on Creep Behavior of Concrete

Difference between creep behaviors of concrete made from stone chips and crushed clay bricks, i.e. brick chips as coarse aggregate are examined by means of creep testing on their representative samples. Two different grades of concrete 17.2 and 27.5 N/mm2 are prepared from brick chips and stone chips using appropriate mix design and are tested for creep for up to 50 days. Stone chips and brick chips aggregates used are selected in a way so that their gradation and fineness modulus remains as close as possible. Results from creep testing shows that concrete made from brick chips as coarse aggregate having same strength as that of concrete made from stone chips shows higher creep strain. As concrete strength increases, the difference in creep strain becomes more pronounced. Also, at initial loading condition, concrete made from brick chips shows higher rate of creep strain than that of concrete made from stone chips.

The Stone Chips and Using in PHC Pipe Piles

This paper describes the preparation of the high-strength concrete with stone chips and the application of the stone chips in PHC pipe piles production. The results show that when the stone chips substitutes for the natural sand, the strength of the concrete increases and the workability of the fresh concrete is improved.

The origins of stone tool technology in Africa: a historical perspective.

The search for the earliest stone tools is a topic that has received much attention in studies on the archaeology of human origins. New evidence could position the oldest traces of stone tool-use before 3.39 Myr, substantially earlier than previously documented. Nonetheless, the first unmistakable evidence of tool-making dates to 2.6 Ma, the period in which Oldowan assemblages first appear in the East African record. However, this is not an unchangeable time boundary, and considerations about the tempo and modo of tool-making emergence have varied through time. This paper summarizes the history of research on the origins of stone knapping in Africa and places the current evidence in a historical perspective.

Quarrying Evidence at the Quispisisa Obsidian Source, Ayacucho, Peru

AbstractArtifacts made from Quispisisa obsidian are widely disseminated in the Peruvian Andes, but the geological source of the Quispisisa geochemical type was only recently located in southern Ayacucho. Following the positive identification of the source in 1999 by Richard Burger and colleagues, we found evidence of broad quarrying activities in unexplored portions of the source area. We describe 34 quarry pits, some as large as 80 m across, together with evidence of early-stage lithic reduction at the source. We encountered high concentrations of reduction debris associated with more extensive knapping in two localities, but our preliminary evaluation of surface evidence suggests that much of the material quarried was removed from the area as intact nodules or after minimal reduction at the source area.

Layered particle based polymer composites for coatings: Part III—Textured coatings obtained via lyotropic liquid crystals

Especially in the course of recent trends to reduce the number of layers of modern automotive coatings the resistance towards stone chipping is becoming an issue. Layered double hydroxide (LDH) based polymer composites are readily accessible materials which have demonstrated to be suitable to impart impact resistance to coatings. The present part of a toolbox of tailor made LDH assemblies describes an economically scalable approach to realize impact resistant coatings that are built on substantially ordered platelets. Unlike other artificial sandwich structured (nano)composites that normally are realized via tedious methods like layer by layer techniques, the parallel alignment of the LDH particles is obtainable with a single coating application process. It originates from an aqueous intermediate that consists of a novel lyotropic liquid crystal phase of polymer stabilized LDH particles.

Contextes et âge des nouveaux restes dentaires humains du Pléistocène moyen de la carrière Thomas I à Casablanca (Maroc)

Contexts and age of the new dental human fossils from Middle Pleistocene deposits at Thomas Quarry I (Casablanca, Morocco) – The Thomas Quarry I locality became famous in 1969 with the discovery of a human half-mandible in a cave. From 1988 onwards, modern controlled excavations took place within the framework of the Franco-Moroccan co-operative project “ Casablanca.” The stratigraphy of Thomas I Quarry is complex and represents several major episodes of coastal sedimentation that are dated to the final Lower and early Middle Pleistocene on the basis of a detailed regional lithostratigraphical and microfaciological study and form the Oulad Hamida Morpho-stratigraphic Unit. Within this MSU, some lithostratigraphic units fossilize a polyphase palaeo-shoreline in which caves have developed. A continental sediment series dated to the Middle and Upper Pleistocene on lithostratigraphical and biochronological evidence and by OSL is preserved in the Hominid Cave (GH). The top of the GH general stratigraphy shows a red complex with abundant microfauna (stratigraphic unit 1). Below this, a multilayer dripstone floor interbedded with loose red sands (stratigraphic units 2-3) caps the lower stratigraphic units (4 and 5). Stratigraphic unit 4 contains artefacts, fauna and hominid fossils and rests on collapsed eolianite blocks imbedded in coarse sands which form stratigraphic unit 5 ; this lowermost intertidal unit fossilizes a notch in the polyphase shoreline. The Acheulean lithic assemblage recovered by recent excavations in GH stratigraphic unit 4 is similar to the series collected at the time of the discovery of the first Homo fossil in 1969. It is manufactured mainly on various quartzites available close to the site as pebbles of small to medium size and some blocks as well as a few flint nodules collected in a secondary position from beach deposits. The flint nodules derive from the phosphatic plateau of the Meseta hinterland and were carried to the ocean by wadis. The assemblage consists of chopper-cores (mainly unifacial unidirectional cores with a retouched cutting edge) and cores, semi-cortical flakes obtained by direct and bipolar knapping, along with rare handaxes made from large flakes or from flat pebbles, handaxe-like cores, hammerstones and anvils. Stone knapping was mainly oriented towards flake production and a few handaxes were probably imported to the site. A rich mammalian macrofauna supplemented by the addition of a few reptiles and birds is associated with the lithics in GH stratigraphic unit 4. The abundance and diversity of carnivores attest to their use of the cave. The most common species is a middle-size canid, with enlarged crushing part of the dentition. The fauna indicates an open woodland environment and suggests an age younger than Tighenif in Algeria, but the remoteness of this latter site, its distance from the seashore, and the fact that it is an open-air site may account for some of the differences. Preliminary taphonomic analysis of the megafauna indicates that the carcasses were processed by carnivores. Cut-marks are still absent from this assemblage despite the association with refitted lithic artefacts, which raises the question of any human role in the bone accumulations. Similar cases of accumulations created by humans, carnivores and porcupines have already been described in the Mediterranean area. However, the studied assemblage comes from inside the cave, whereas any human occupation may well have been concentrated closer to the entrance. Geological studies have demonstrated that unit 4 containing the assemblage results from several sedimentary processes having possibly mixed artefacts with bones previously accumulated by predators. Between 1994 and 2005, four teeth of Homo were recovered in stratigraphic unit 4, a right upper premolar (ThI 94 OA 23-24), another right upper premolar (ThI 95 SA 26 no 89), a first left upper incisor (ThI 95 SA 26 no 90) and a left upper premolar (ThI 2005 PA 24 no 107). The teeth are larger than those of modern humans and show moderate to heavy wear Laser ablation ICP-MS dating combining tESR and U-series data for modelling U-uptake has given an US/ ESR age of 501 ka for a human premolar while new OSL measurements yielded an age of 420 ± 34 ka for sediments immediately above the dated tooth and 391 ± 32 ka below. Nevertheless, biostratigraphy and lithostratigraphy point to greater antiquity, towards the base of the Middle Pleistocene. + 94 − 76

AN APPRAISAL OF TWO TRACER METHODS FOR ESTIMATING TILLAGE EROSION RATES UNDER HOEING TILLAGE

An increasing recognition of tillage erosion processes has shown that soil redistribution by tillage directly contributes to soil loss in mechanically and nonmechanically agricultural areas worldwide. Soil translocation by tillage is normally measured by means of tracers, with which a volume of soil is labelled, and therefore yielding tillage erosion rates in a field. Two tracer methods for estimating tillage erosion rates were appraised to examine the application adaption to local conditions in the hilly areas, southwestern China, in terms of the accuracy, measurement sensitivity, manipulation facility, and time cost. The two tracer methods had a similar measurement accuracy of soil translocation. However, for the magnetic tracer method the result of tracer distribution after tillage was immediately obtained in the field, while there was a need to do a follow-up indoor determination for the stone chip method. The magnetic tracer method only required collecting a small volume of soil samples, while a large quantity of soil (i.e. all the soils into which tracers possibly redistributed) was collected to recover all the stone chips from tilled soils. As a result, the magnetic tracer method would be much time saving compared to the stone chip method. It is suggested that the magnetic tracer method would rather be used when there are large quantities of sampling plots to be measured on steep hillslopes of the hilly areas where hoeing tillage is practiced.

An Appraisal of Two Tracer Methods for Estimating Tillage Erosion Rates under Hoeing Tillage

An increasing recognition of tillage erosion processes has shown that soil redistribution by tillage directly contributes to soil loss in mechanically and nonmechanically agricultural areas worldwide. Soil translocation by tillage is normally measured by means of tracers, with which a volume of soil is labelled, and therefore yielding tillage erosion rates in a field. Two tracer methods for estimating tillage erosion rates were appraised to examine the application adaption to local conditions in the hilly areas, southwestern China, in terms of the accuracy, measurement sensitivity, manipulation facility, and time cost. The two tracer methods had a similar measurement accuracy of soil translocation. However, for the magnetic tracer method the result of tracer distribution after tillage was immediately obtained in the field, while there was a need to do a follow-up indoor determination for the stone chip method. The magnetic tracer method only required collecting a small volume of soil samples, while a large quantity of soil (i.e. all the soils into which tracers possibly redistributed) was collected to recover all the stone chips from tilled soils. As a result, the magnetic tracer method would be much time saving compared to the stone chip method. It is suggested that the magnetic tracer method would rather be used when there are large quantities of sampling plots to be measured on steep hillslopes of the hilly areas where hoeing tillage is practiced.

Non‐destructive detection of corrosion applied to steel and galvanized steel coated with organic paints by the pulsed phase thermography

AbstractOrganic coatings in the automobile industry have to resist corrosion and mechanical damage from stone chipping. Currently, no tool is established in industrial non‐destructive applications for analyzing the damage of stone‐impacts and the following corrosion after accelerated corrosion tests. Measurement methods such as the scanning Kelvin probe can analyze the corrosion progress in a detailed manner, but with a long measurement time. The pulsed phase thermography (PPT) is a non‐destructive tool to analyze inhomogeneities and defects in materials, with a huge field of applications existing. The present work shows advances in using the PPT to detect propagation of corrosion under coatings. Physical principles of the mechanism of the corrosion detection under coatings are described. Results of measurements of organic coatings on carbon steel as well as of organic coated galvanized steel show the corrosion propagation. Influencing factors to the measurement such as the thickness of the coatings are investigated, but no significant effect on the quality of the analysis was found. The corrosion progress can be monitored by the PPT fast and reliably. The achieved results correlate with the theoretical basis and the test results after surface characterization and destructive analysis of samples.

The archaic stone tool industry from Barranco León and Fuente Nueva 3, (Orce, Spain): Evidence of the earliest hominin presence in southern Europe

The Barranco León and Fuente Nueva 3 sites are located in the Guadix-Baza Basin in Orce (Andalusia, Spain) about 80 km from the Mediterranean Sea. The sites were accumulated in swampy areas near the paleo-lake Baza’s eastern shoreline. There, hominins and hyenas competed for access to large herbivore carcasses abandoned by carnivores. The ages of the Barranco León and Fuente Nueva 3 sites have been evaluated from large and small mammal biochronology, magnetostratigraphy and also by ESR to around 1.4–1.2 Ma, respectively. Both sites have yielded fauna and lithic artefacts in situ. Systematic excavations at Barranco León and Fuente Nueva 3 have been underway since the 1990’s and contribute to growing evidence of hominin presence in southern Europe well before 1 Ma. The two lithic assemblages show strong similarities. At both sites, the artefacts were knapped from tabular flint and limestone pebbles collected nearby. The assemblages are composed mainly of small, non modified flakes and angular fragments, as well as some cores. Larger limestone heavy duty tools and cores are also present. There are no standardized small or large tools. Stone knapping was carried out using hand held and bipolar-on-an-anvil reduction strategies in accordance with raw material constraints and probably also desired product morphology. The assemblages are characterized by widespread use of unidirectional knapping methods. Reduction strategies were progressively adapted as the cores evolved into different forms. The Barranco León and Fuente Nueva 3 stone tool assemblages express a variant of Oldowan or Mode 1 technology that may be considered to be more complex than that observed at some earlier African sites, mainly because of the systematic use of extended orthogonal knapping episodes producing multiplatform cores and the differential use of two types of raw materials for making small cutting tools and larger percussion instruments.

Generalization, inference and the quantification of lithic reduction

Today studies of lithic technology almost invariably employ models of the reduction process, and often models of the extent of reduction that specimens and classes of tools have undergone. Debates about the explanation of lithic assemblage variability are based upon methods for inferring the nature and extent of reduction. In this paper, we construct a conceptual framework for evaluating the competing reduction indices for estimating the extent of flake retouching. With this framework we offer a new synthesis of reduction indices and the debates that have surrounded their use.