W. James Stemp

Quantifying Microwear on Experimental Mistassini Quartzite Scrapers: Preliminary Results of Exploratory Research Using LSCM and Scale-Sensitive Fractal Analysis

Although previous use-wear studies involving quartz and quartzite have been undertaken by archaeologists, these are comparatively few in number. Moreover, there has been relatively little effort to quantify use-wear on stone tools made from quartzite. The purpose of this article is to determine the effectiveness of a measurement system, laser scanning confocal microscopy (LSCM), to document the surface roughness or texture of experimental Mistassini quartzite scrapers used on two different contact materials (fresh and dry deer hide). As in previous studies using LSCM on chert, flint, and obsidian, this exploratory study incorporates a mathematical algorithm that permits the discrimination of surface roughness based on comparisons at multiple scales. Specifically, we employ measures of relative area (RelA) coupled with the F-test to discriminate used from unused stone tool surfaces, as well as surfaces of quartzite scrapers used on dry and fresh deer hide. Our results further demonstrate the effect of raw material variation on use-wear formation and its documentation using LSCM and RelA.

Discrimination of surface wear on obsidian tools using LSCM and RelA: pilot study results (area-scale analysis of obsidian tool surfaces).

This pilot study tests the reliability of laser scanning confocal microscopy (LSCM) to quantitatively measure wear on experimental obsidian tools. To our knowledge, this is the first use of confocal microscopy to study wear on stone flakes made from an amorphous silicate like obsidian. Three-dimensional surface roughness or texture area scans on three obsidian flakes used on different contact materials (hide, shell, wood) were documented using the LSCM to determine whether the worn surfaces could be discriminated using area-scale analysis, specifically relative area (RelA). When coupled with the F-test, this scale-sensitive fractal analysis could not only discriminate the used from unused surfaces on individual tools, but was also capable of discriminating the wear histories of tools used on different contact materials. Results indicate that such discriminations occur at different scales. Confidence levels for the discriminations at different scales were established using the F-test (mean square ratios or MSRs). In instances where discrimination of surface roughness or texture was not possible above the established confidence level based on MSRs, photomicrographs and RelA assisted in hypothesizing why this was so.

Laser profilometry and length‐scale analysis of stone tools: second series experiment results

Based on the need to develop a method to reliably and objectively document and discriminate the use-wear on archaeological stone tools, Stemp et al. (2009) tested whether the surface roughness measured on experimentally worn stone tools used on different contact materials could be discriminated. Results of these initial experiments indicated that discrimination was possible and also determined the scales over which this discrimination occurred. In this article, we report the results of additional experiments using the same method on a second set of tools to test its reliability and reproducibility. In these experiments, four flint flakes were intensively used for 20 min on either conch shell or dry deer antler. The surface roughness or texture of the stone tools was measured by generating 2D profiles using a UBM laser profilometer. Relative lengths (RLs) calculated from the profiles were used directly as characterization parameters and subsequently compared statistically at each scale using the F-test to establish a level of confidence for the differentiation at each scale represented in the measured profiles. The mean square ratios of measurement data were used to determine whether the variation in roughness was statistically significant and to what level of confidence. The scales at which there was a high level of confidence were the ones at which the tools were differentiable. The results of these experiments confirm our previous findings that RLs, over certain scale ranges, can discriminate the stone tool surface wear profiles produced by the different contact materials.

The Quantification of Microwear on Chipped Stone Tools: Assessing the Effectiveness of Root Mean Square Roughness (Rq)

Abstract Although considerable progress has been made by archaeologists and materials scientists toward the development of a method to quantitatively document use-wear on stone tool surfaces, experimentation and refinement of methods continue. The experimental program tests root mean square roughness (rms or Rq) of measured profiles for their ability to quantitatively discriminate the surface textures, or roughness, of experimental stone tools used on five contact materials (shell, wood, dry hide, dry antler, and soaked antler). It employs a method for evaluating texture characterization parameters based on their ability to discriminate wear, and to determine a level of confidence for the discrimination, using the F-test. The results of this experiment demonstrate that Rq is not consistently reliable in discriminating measured profiles based on the wear caused by different contact materials on the stone tools.

Surface analysis of stone and bone tools

Microwear (use-wear) analysis is a powerful method for identifying tool use that archaeologists and anthropologists employ to determine the activities undertaken by both humans and their hominin ancestors. Knowledge of tool use allows for more accurate and detailed reconstructions of past behavior, particularly in relation to subsistence practices, economic activities, conflict and ritual. It can also be used to document changes in these activities over time, in different locations, and by different members of society, in terms of gender and status, for example. Both stone and bone tools have been analyzed using a variety of techniques that focus on the observation, documentation and interpretation of wear traces. Traditionally, microwear analysis relied on the qualitative assessment of wear features using microscopes and often included comparisons between replicated tools used experimentally and the recovered artifacts, as well as functional analogies dependent upon modern implements and those used by indigenous peoples from various places around the world. Determination of tool use has also relied on the recovery and analysis of both organic and inorganic residues of past worked materials that survived in and on artifact surfaces. To determine tool use and better understand the mechanics of wear formation, particularly on stone and bone, archaeologists and anthropologists have increasingly turned to surface metrology and tribology to assist them in their research. This paper provides a history of the development of traditional microwear analysis in archaeology and anthropology and also explores the introduction and adoption of more modern methods and technologies for documenting and identifying wear on stone and bone tools, specifically those developed for the engineering sciences to study surface structures on micro- and nanoscales. The current state of microwear analysis is discussed as are the future directions in the study of microwear on stone and bone tools.

Experiments in ancient Maya bloodletting: quantification of surface wear on obsidian blades

It is widely accepted that the ancient Maya practiced sacrificial bloodletting to communicate with their dead ancestors and the gods. Implements to draw blood included a variety of tools, including stone blades made of obsidian. Evidence for bloodletting is based on ethnohistoric accounts provided by the Spaniards, ethnographic observation of modern Maya rituals, iconography depicting bloodletting, hieroglyphic references, and the recovery of artifacts from ritual contexts. However, evidence for bloodletting based on the surface wear on the obsidian blades themselves is inconclusive and difficult to identify. Recent work for quantifying use-wear on stone tools using laser scanning confocal microscopy (LSCM) and scale-sensitive fractal analysis, based on relative area (RelA), has led to an experimental program to quantitatively document wear patterns on replicated obsidian tools. Three obsidian blade segments were used to cut raw beef as a proxy for bloodletting. Our results demonstrate that surface roughness on the blade segments can be documented using RelA, but discrimination of the used from the previously unused surface was only possible in one of the three cases; the original surface structure of an obsidian blade plays a role in wear formation and its subsequent documentation based on RelA.

Evidence for Maya Household Subsistence and Domestic Activities: Use-Wear Analysis of the Chipped Chert Assemblage from Pook's Hill, Belize

Abstract From 1999–2005, the Belize Valley Archaeological Reconnaissance Project excavated Pook’s Hill (PKH-1), a single plazuela group located in the Roaring Creek Valley, Cayo District, Belize. Artifacts recovered at Pook’s Hill date predominantly to the Late and Terminal Classic (A.D. 700–950) and can be stratigraphically segregated into two distinct occupation phases, namely a Late Classic (A.D. 700–830) and a Terminal Classic-Early Postclassic (A.D. 830–9507+) phase. The chipped chert and chalcedony tools from the two phases were included in a combined program of low- and high-power use-wear analysis to reconstruct aspects of the socioeconomy. The results of the analyses reveal that the site’s inhabitants produced and used both formal and informal tools for a wide variety of subsistence and domestic tasks, and for the production of some utilitarian items. Stone tool use-wear evidence and the recovery of small quantities of other artifacts suggest that the Maya from Pook’s Hill produced more valuable objects of bone, stone, and shell, although it is difficult to accurately identify craft-production activities at the site from the context of recovery. Despite some variation in the specific activities undertaken with the chipped stone tools over time, the organization of lithic technology at Pook’s Hill did not change significantly from the Late Classic into the Early Postclassic period.

Coastal Maya Obsidian Tool Use and Socio-Economy in the Late Postclassic-Early Spanish Colonial Period at San Pedro, Ambergris Caye, Belize

Microscopic use-wear analysis of the obsidian artifacts recovered from Late Postclassic-Early Spanish Colonial occupations at the site of San Pedro yields useful information for interpreting Maya socio-economic activities. Obsidian traded into the community was used for a variety of tasks with emphasis placed on subsistence and domestic manufacture associated with marine resources, including intermittent and contingent crafting. Trade in obsidian and marine resources likely provided San Pedro community members access to inland economic networks and enabled the acquisition of resources not found on the caye. Microwear on chert and obsidian tools indicates relative stability in the traditional lives of the San Pedro Maya in the 15th–17th centuries a.d. Although the San Pedranos likely suffered to some degree from coastal raiding and the introduction of epidemic diseases by the Spaniards, their off-shore location provided them some protection from the upheaval experienced by the Maya in mainland communities.

Quantifying lithic microwear with load variation on experimental basalt flakes using LSCM and area-scale fractal complexity (Asfc)

Working load is one factor that affects wear on stone tools. Despite the recognition of the importance of the relationship between working load and the development of microwear on stone tools, there have been few attempts to quantify differences in wear due to changes in load. In a controlled experiment, we used 30 basalt flakes knapped from raw material collected in Olduvai Gorge, Tanzania, Africa, to cut oak branches for the same number of strokes. For each flake, a different loading level was applied starting at 150 g and increasing by increments of 150 g to a maximum load of 4.5 kg. A laser scanning confocal microscope was used to mathematically document the surface texture of the flakes. The worn surface data were compared using area-scale fractal complexity (Asfc), calculated from relative areas, to determine the degree to which variation in loading significantly affected the amount of wear on the flake surfaces. Our results indicate that working load does play a role in the development of lithic microwear on these flakes and that discrimination of two worn flake surfaces, using mean square ratios of Asfc, based on variable load is consistently possible with load differences between ~100 g and 4.5 kg. However, discrimination of microwear on flake surfaces was not consistent for all load level differences and discrimination became less consistent when working load differences were below ~100 g.

Coastal Maya Obsidian Trade in the Late Postclassic to Early Colonial Period: The View From San Pedro, Ambergris Caye, Belize

ABSTRACT Although substantial work has been done to reconstruct ancient Maya coastal trade from the Late Preclassic through the Early Postclassic periods (400 BC–AD 1200), relatively little is known about trade activity along the Caribbean Coast in Late Postclassic and Early Colonial times (ca. AD 1400 to 1700). By focusing on obsidian artifacts from the site of San Pedro on Ambergris Caye, Belize, one of the few coastal sites for which data are available for the Postclassic to Colonial transition, we attempt to understand how Maya procurement, production, and use of obsidian were organized, and the effect the arrival of the Spaniards had on access to obsidian. The Spanish presence in the Yucatan Peninsula clearly changed Maya life in numerous ways; however, the evidence from San Pedro suggests strongly—although it is not yet unequivocal—that Maya communities along the coast were still able to access obsidian, primarily from the Guatemalan highlands. With comparatively good access to obsidian for blade production, the site appears to have served as an important link in both long-distance and intraregional socioeconomic systems as a way station for moving goods up and down the Caribbean Coast and by funneling resources via a coastal-inland trade network.