Reports the results of the XRF analysis of 132 artifacts from a severely disturbed site on Butte Creek in the Western Cascades of Oregon. We took a look at this particular site because it lay in a geographic area in which almost no previous provenience studies had been undertaken. The trace element analysis of these artifacts not only demonstrated the utility of obsidian studies at disturbed sites, but also provided an example of the serendipitous good luck that sometimes accompanies a geochemical fishing expedition like this one - a new local obsidian source was identified.

Reports the results of XRF analysis of an obsidian biface fragment from the Fort Hill Hopewell Site in Ohio. Obsidian Cliff in Yellowstone National Park proved to be the geologic source of the artifact. The results of this report were the basis for an article that appeared in Archaeology in Eastern North America 26:33-39 (1997 - Bradley Lepper, Craig E. Skinner, and Christopher M. Stevenson).

This report is a bit more complex than our average model but contains the results of some interesting experimental studies that we conducted on the effects of heat on obsidian hydration rim measurements and rim survival. The analyzed artifacts were collected from two sites that had been severely burned in a 1993 forest fire in the Deschutes National Forest of Oregon. For more information on the effects of fire on hydration analysis, see the Other Articles and Report section below.

During the PGT-PG&E Pipeline Expansion Project (PEP) carried out in the early 1990's, over 9,500 obsidian artifacts from 133 Oregon, California, and Idaho archaeological sites were selected for obsidian characterization studies (Table 1). The trace element composition of 9,059 of these items was determined by X-ray (XRF) fluorescence spectrometry and the resultant elemental abundances were used to identify the geochemical sources of the samples (Skinner 1995a). All Oregon and Idaho artifacts were analyzed by Richard E. Hughes (Geochemical Research) who, along with BioSystems Analysis, also characterized the California specimens. After geologic source identification, the majority of the obsidian artifacts were then examined for the presence of obsidian hydration rims. Several chapters, including all of those associated with the obsidian studies, may be downloaded here.

Abstract: The Little Lake biface collection comprises 26 complete biface preforms. The bifaces are believed to have been found in a cache acquired near the vicinity of the town of Little Lake, Inyo County, California. All the complete bifaces have hydration values falling within a very tight range measuring from 3.5 to 3.8 microns and were determined to have come from the West Sugarloaf subfield of the Coso quarry cluster. These rim readings signify a brief single episode of time and would date to the very late Haiwee or the early Marana Periods in the Owens Valley cultural sequence or ca AD 1300. The cache would lend some limited support to the continued use of large biface cores as a means of production and transport of portable units of toolstone significantly later than might be expected in a volume/mass that is surprising.

The Northern Great Basin Prehistory Project is a joint undertaking of the University of Oregon (UO) Archaeological Field School, UO Department of Anthropology, Museum of Natural History, Department of Geography, and Office of Summer Sessions, the Lakeview, Prineville, and Burns District Offices of the Bureau of Land Management, the Deschutes (Bend) and Malheur (John Day) National Forests, and the Sundance Archaeological Research Fund and Department of Anthropology, University of Nevada, Reno (UNR).

If you have an interest in the effects of fire on obsidian artifacts, this is a must-have publication. This volume consists of 14 papers based on presentations given at a 1999 symposium, The Effects of Fire/Heat on Obsidian, that was held at the 33rd Annual Meeting of the Society for California Archaeology (Sacramento, California). To download a short (260K) additional erratum sheet, click HERE

Abstract: Seventeen known and four unknown sources among 90 obsidian artifacts were identified from the Lost Dune and McCoy Creek sites on the east side of Blitzen valley, Harney County, Oregon. Changing distributions and abundances of obsidian sources identified in four prehistoric periods (3,500-2,000 B.P., 2,000-500 B.P., A.D. 1400s and A.D.1500s) suggest eastern Blitzen Valley people used a limited resource area in the middle two periods. For the period from 2,000 to 500 B.P., obsidian was identified only from sources in and adjacent to Harney Basin and in the northern Catlow Valley - the "western Malheur.Catlow area. Then, briefly in the A.D. 1500s, pottery-using visitors brought to Lost Dune ample obsidian from sources well east of Harney Basin in the Owyhee River drainage.

From the Abstract: Nonhydrated obsidians are quenched magmatic liquids that record in their chemical composition details of the tectonic environment of formation and of the differentiation mechanisms that affected their subsequent evolution. This study attempts to analyze, in terms of geologic processes, the compositional variations in the Subalkalic obsidians... New major- and trace-element determinations of 241 samples and a compilation of 130 published major-element analyses are reported and interpreted.

From the Abstract: Peralkaline rocks are one of the characteristic products of non-origenic magmatism, and the development of peralkaline silicic magmas continues to be a problem of special interest to petrologists. The problem is complicated by the fact that crystallization of these highly alkaline melts commonly result in significant chemical changes, such that the study of quenched liquids (glasses) is probably the only reliable approach to magma compositions. In this report, all acceptable analyses of oversaturated peralkaline obsidians are listed and compared in an attempt to provide a sound basis for further studies of peralkaline silicic magmatism.

This unfinished report by Nevada archaeologist Joe Moore (now retired but formerly of the Nevada Department of Transportation) was last substantially updated in about 2002. Although the toolstone project remains incomplete, much of the information it contains (both the data and the source information) is unavailable elsewhere. And so, with our thanks and the permission of Joe, we present the report in it's most recently updated version.

This piece of research, the first substantial one that we finished under the name of Northwest Research, was completed in 1991. We always felt that this was a nicely done investigation although the final project report susequently disappeared deep into the vast murky reservoir of U. S. Forest Service gray literature. For more on the project, click HERE.

Abstract: Six hundred sixty-two obsidian samples from sources in Oregon were characterized by instrumental neutron activation analysis (INAA) in order to establish the number of geochemical groups present. Neutron irradiations were performed at the Missouri University research reactor (MURR) and gamma-ray spectra were measured with high-purity germanium (HPGe) detectors to determine absolute concentrations for 27 elements.

Thirty-six different geochemical groups were formed. Four groups were found in the Malheur National Forest of Grant County. Six groups were found in Harney County, three of them near the town of Burns. Three correlated groups, part of an extensive ash-flow tuff, were found in the Ochoco National Forest area of Harney County. Seven groups were found at Glass Buttes, Lake County, where x-ray fluorescence (XRF) showed only six groups. Nine groups were found in Lake County. Four groups were found in Newberry Caldera. Previously, based on XRF, it was thought that only two groups existed. A single geochemical group was identified in Klamath County. Two chemical groups were found in Lane County.

Most of the above chemical groups were successfully separated using an abbreviated-INAA procedure (only the elements Na, Mn, and Ba). Only in the Ochoco National Forest was the procedure unsuccessful.

Use of the database on an archaeological problem was demonstrated by analyzing thirty-one artifacts from the Robins Spring site, on Glass Buttes, by procedures in this study. The results indicate the artifacts were made from several of the obsidian sources on Glass Buttes as well as Yreka Butte, a source near Glass Buttes.

Abstract: Archaeological studies of lithic material procurement and use have traditionally focused on raw material quality and proximity to source as sole indicators for selection of particular materials for stone tool manufacture. Yet this effectively denies the role of human action and belief in the choice of lithic materials. The Glass Mountain obsidian quarry provides evidence of the integration of prehistoric belief systems into toolstone procurement patterns as visible through differential toolstone use in prehistory and the selection of specific raw material types for particuular categories of objects.

Large obsidian bifaces from northern California have long been known as non-utilitarian ceremonial and wealth objects. Despite their uniform and stylized shape, bifaces were manufactured from several different obsidiain sources. Glass Mountain in Siskiyou County, California was one source for black obsidian bifaces. The lithic assemblage at Glass Mountain and X-ray fluorescence data from the surrounding region indicate that this obsidian was used almost entirely for biface production, and was neglected as a source for utilitarian objects. Just as obsidian objects fulfilled utilitarian of non-utilitarian functions, obsidian sources retained special roles within the context of prehistoric cultura and belief systems.

Ultimately, differential use of Glass Mountain obsidian lies in the context of cultural beliefs, which hold it as a special source to be used exclusively for the production of valued objects. Certainly Glass Mountain is not the only obsidian utilized for value objects, but it is unique in that it was used almost entirely for non-utilitarian purposes, while other nearby obsidian was exploited for utilitarian objects. The cultural context of Glass Mountain obsidian utilization varies across and within territorial and geographic boundaries, yet despite cultural differences, the concept of value is intricately linked with Glass Mountain obsidian and the large bifaces made from it. In this sense, the quarry was in itself also an active agent, which gave value to things. It provides evidence for integration of prehistoric belief systems into toolstone procurement and use patterns through the selective use of Glass Mountain obsidian for ceremonial and value objects.

Abstract: Archaeologists have been undecided for years on the purpose or intent of ancient lithic caches that have been discovered throughout the landscape in various parts of the world. These caches have varied by morphology, typology, size, and location. This dissertation discusses a brief history of lithic caches, their possible meanings and purposes, and examines four lithic caches that were discovered in the United States of America, for any possible relationships and similarities. These four lithic caches are concentrated on Idaho's south central Snake River Plain within a range of 110 km of each other. Non-professionals discovered three caches; another was professionally excavated. The Cedar Draw and China Creek Caches have never been placed into the archaeological history record and are catalogued and analyzed here for the first time. Even though the caches were found at different elevations and landscapes they were all located near a water source that provided visibility of the surrounding terrain. No debitage was found directly at the sites, and osteological evidence was not present. The artifacts in the Simon Cache and the China Creek Cache appear to be made from exotic materials procured from a non-local stone sources suggesting long distance movement or trade. Both caches were discovered near possible ancient trade routes. The Cedar Draw Cache and the Rock Creek Cache exhibit the same morphology and typology. A strong probability exists that they were manufactured from the same ignimbrite material source. The four caches vary in age from the Clovis culture (11,200 B.P. to 10,900 B.P.) to approximately 3,000 B.P.

Abstract: Recent studies of the Late Archaic period in the Great Basin have identified major changes in settlement, subsistence, and technology compared to those seen during the Middle Archaic. The concern of this study is whether the Late Archaic at the Birch Creek Site (35ML181) is marked by a significant change in adaptive strategy, as it appears to be in much of the Great Basin. This thesis uses the sediments encountered and material recovered from the 2006 excavations of the Birch Creek Site, including datable samples, ancient pollen, ground and chipped stone tools and debitage, faunal remains, and evidence of ceramic technology as evidence of the adaptive strategy of Late Archaic people at the Birch Creek Site. The Late Archaic component was expected to be structured differently from earlier materials if it were created by a new group of people practicing a new adaptice strategy beginning during the Late Archaic. Comparisons of Late Archaic artifact assemblages to previously studied materials from the Middle Archaic component of the Birch Creek Site were used to determine if a discontinuity in adaptive strategy exists. Material evidence of settlement, subsistence, and technological organization do not reflect direct continuity, nor do they indicate an abrupt shift, in adaptive strategies. The adaptive strategy duing the Late Archaic occupation of the Birch Creek Site appears to be a product of relatively local conditons related to subsistence and tool raw material resources, with some indications of wider regional interactions.

Abstract: Identifying lithic sources is central to understanding toolstone use by prehistoric hunter-gatherer groups. The distribution of archaeological materials in relation to geologic sources creates a spatial pattern of use that varies through time. These patterns of distribution in conjunction with analysis of technological organization can be used to infer behavior, especially levels of mobility. This thesis presents geochemical data from a wide-scale sourcing study in the Bonneville basin of western Utah and eastern Nevada. Results of this investigation are presented, including discussion of newly identified geologic source groups and further characterization of previously identified sources, outcome of X-ray fluorescence analysis on approximately 600 fine-grained volcanic (FGV) artifacts from a host of open sites in the Old River Bed delta and from caves/rockshelters including Danger Cave, Bonneville Estates Rockshelter, and Camels Back Cave, and a brief look at how the inhabitants of this region varied FGV-toolstone use through time.

Abstract: This study examines igneous toolstone procurement and mobility strategies during the Archaic Period (9,000 B.P. - 2,400 B.P.) on the Coconino Plateau, Arizona. Relying on X-ray fluorescence analysis to determine the geologic source of 271 diagnistic projectile points, I investigate obsidian and fine-grained volcanic (FGV) source preferences and small-scale mobility patterns surrounding the San Francisco and Mt. Floyd Colcanic Fields. Included in this study is a sampling survey designed to provide a comparative geochemical source libraary (n=355) for the region. The baseline survey served to ascertain the various performance characteristics of each raw material. These performance characteristics were then used as a foundation for a procurement model intended to explain the highly slective and patterned procurement behavior exhibited by the hunter-gatherers that occupied the area. I adapted the lithics-based model, termed the procurement preference model (PPM), from subsistence-based diet breadth models.

Archaic Period bands occupying the Coconino Plateau exploited only a handful of the lithic source options available in the research area. I assert that hunter-gatherers optimized procurement decisions and sought to maximize rate of energy return by choosing the highest-quality lithic materials. I further argue hunter-gatherers practiced a disembedded procurement strategy once within the study area. Lastly, the specific igneous toolstone sources comprising the optimal set of lithic sources remained unchanged throughout the 6,600 years of the Archaic, although the overall percentage of the entire optimal set increased as observed in the projectile point sample. Thus, I conclude lithic source procurement became more specialized over time.

From the Introduction: The research that is reported in this project deals primarily with obsidian characterization. I have gone beyond this topic, though, in presenting an overview of the many other geological, geomorphological and archaeological properties of this natural glass. The project, as a result, is divided into five distinct, but interrelated parts, in addition to an extensive bibliography and a number of appendices.

This part, the first one, is an introduction to the rest of the project. It will give the reader a general idea of the structure that I used to organize this paper and of what I intended to achieve through the research that is reported. Topics touched on here will be discussed in greater detail in later sections.

Part Two of this project is concerned with providing an overview of the many geological and geomorphological characteristics and properties of obsidian. This includes its geographic distribution, the forms in which it occurs, how it is transported after extrusion, its macroscopic and microscopic properties and its chemical composition. An understanding of these characteristics provides a step towards comprehending how the physical and geochemical properties of obsidian may be studied and how the results can be utilized in archaeological problem-solving.

Part Three describes the ways in which analysis of the petrographic, optical and geochemical properties of obsidian can be applied to archaeological studies. Specifically, I will discuss obsidian characterization methods, the ways in which characterized obsidian can be used to infer prehistoric contact networks and obsidian geochronologic techniques.

Part Four comprises the main body of the project, a systematic investigation of some of the attributes of obsidian that may be used to characterize, or distinguish, a particular geologic source of glass. In Part Four, I will describe the ten Oregon sources that were sampled for this research and the different ways in which they were successfully and unsuccessfully "fingerprinted" or characterized. All of the sampled obsidian sources were known or suspected to be prehistoric quarry sites.

Abstract: This research integrates the analysis of obsidian geochemistry with investigation on the effects of forest fires on obsidian artifacts in surface assemblages. The first component of this project investigated the nature of heat altered obsidian at a prehistoric quarry sites following the 1996 Dome Fire in the Jemez Mountains of northern New Mexico. Burned artifacts were examined to discern indicators of heat alteration in obsidian and to measure the impact of fire on obsidian hydration (OH) bands. Descriptive categories developed to encompass a range of fire effects are provided here as a tool for identifying heat-altered obsidian in archaeological contexts. Measurement of obsidian hydration in artifacts collected from across the site demonstrated substantial loss and alteration of OH information, as well as positive correlation of OH loss/alteration with degree of burn severity.

The second component of the project investigated the role of obsidian geochemistry in fire effects, especially obsidian vesiculation. Intrasource and intersource geochemical analyses of obsidian trace element composiiton were integrated with analysis of major/minor elements, and with analysis of the water content as a volatile constituent. Results show elemental homogeneity among the Dome area Obsidian Ridge/Rabbit Mountains obsidians of the Cerro Toledo Rhyolite (CTR), demonstrate a cogenic realtionship among geographically separate CTR deposits, and confirm that these obsidians are chemically distinct from Valles Rhyolite (VR) glasses as Cerro del Medio. Analyses of obsidian water content using loss-on-ignition (LOI) and infrared spectroscopy (FTIR) demonstrate the efficacy o both techniques for archaeological applications. Water contents were found to be low in VR samples, but high and variable in CTR samples. These results accord with the expectation of higher and more variable water contents in glasses from pyroclastic deposits, as compared with lower water contents in glasses from extrusive volcanic contexts This study provides a new example in which obsidian water content is high and variable within a single chemical type. This example provides support for the inclusion of water contents as a compositional variable in the OH dating model and demonstrates the utility of integrating analysis of both elemental and volatile composition into archaeological practices of obsidian geochemical analyses.

Abstract: Despite several decades of archaeological work in both the western Great Basin and the Sierra Nevada foothills, little is known about how prehistoric populations used the high elevation areas between these two regions. This thesis involved the investigation of six high elevation sites at Taboose Pass in Kings Canyon National Park, California. Through a combination of surface collection, limited test excavation, two distinct archaeological patters were identified. The first is an earlier (ca-3500 B.P.-1350 B.P.) limited-use pattern characterized by dense lithic scatters related to obsidian procurement by groups living on the western slope of the Sierra Nevada. The second pattern is a later (ca. 1350 B.P.-historic contact) intensive-use pattern with rock ring features, midden soil, and a variety.

From the Abstract: Geochemical characterization methods are commonly used in the reconstruction of prehistoric raw material use and procurement systems. Trace element studies of lithic source materials and artifacts, specifically those made of obsidian, can reveal important information about the environmental and cultural factors which influence the prehistoric distribution of raw material. The current investigation use geochemical characterization methods and data to document and evaluate the distribution of geologic and artifact obsidian that originates from the Silver Lake/Sycan Marsh (SL/SM) obsidian source. This large and prehistorically significant source is located in western Lake County, Oregon. Few source descriptions or artifact distribution studies exist for SL/SM obsidian. However, over the past decade, a significant increase in the use of geochemical characterization methods has generated a wealth of data for Oregon obsidian sources. This thesis synthesizes the results of the geochemical characterization analysis of 392 geologic obsidian specimens collected from the SL/SM source area and 1,938 SL/SM obsidian artifacts recovered from over 200 sites in Oregon, Washington and California. The artifact analytical data were derived from previously characterized artifact collections compiled and archived in an extensive database. A subset of artifacts were characterized for the purpose of this study.

Abstract: Regional studies of obsidian artifacts in the south-central Andes have shown thath over 90% of the analyzed obsidian artifacts from the Lake Titicaca Basin belong to a single geochemical obsidian type. A decade ago researchers identified the geologic origin of this obsidian as the Chivay/Cotallalli source, located 180km west of Lake Titicaca above the Colcaa Valley in Arequipa at 71.5355º S, 15.6423º W (WGS84), and at 4972 meters above sea level. This research project focused on the obsidian source and adjacent lands within one day's travel from the source. The project included a 33km² survey, 8 test units, and in-depth lithic attribute analysis. Mobile GIS (Arcpad) was used extensively during survey. A substantial quarry pit and an obsidian workshop were examined closely, as were consumption sites in nearby areas. The results of this study found that the earliest diagnostic materials at the source date to he Middle Archaic (8000-6000 BCE) and that intensification of obsidian production occurred earlier than previously recognized, at circa 3300 BCE. Increased obsidian production appears to have been focused on the acquisition of large (>20cm) and homogeneous obsidian nodules, although the formal tools produced with obsidian were predominantly small projectile points. It is argued that the acquisition of large, homogeneous nodules was prioritized because the production potential of large nodules was highest, and because obsidian was associated with competitive display among early aggrandizers. The timing and economic associations of obsidian production and circulation suggest that the possession of large obsidian pieces in the Titicaca Basin was a demonstration of social connections to distant resources, and to regional trade networks that emerged with regular camelid caravan transport networks. Obsidian artifacts were not niherently "prestige goods"; rather, it is suggested here that obsidian was the least-perishable of a number of cultural goods distributed by an expanding network of caravans that linked communities in the region. The acquisition and consumption of these cultural goods was a demonstration of economic connections and cultural influence during the dynamic period of incipient social inequity between the Terminal Archaic (3300-2000 BCE) through the Middle Formative (1300-500 BCE).

Abstract: Technological debitage analysis can be an aid in assessing discard context, as well as overall site integrity. Related to this is the well-known use of obsidian hydration to identify scavenging behavior. Obsidian hydration cut locations are often determined in the obsidian lab; the archaeologist soliciting the hydration assessment does not usually select the specific locations. By identifying features on the artifact that can be attributed to particular reduction techniques or methods and acquiring hydration measurements from those locations, transformational processes and prehistoric behavior are better elecited. An example from an archaeological site located in the southern San Joaquin Valley of California is presented.

Introduction: Danger Cave (42To0013) is located on the western edge of the Bonneville Basin, within Tooele County, Utah, just north of Wendover, Utah. It is a classic Great Basin site containing well stratified deposits that have a high degree of organic preservation and are well dated. It contains rich evidence of cultural occupations spanning the terminal Pleistocene and Holocene. Obsidian artifacts, including some debitage with provenience, are abundant in the assemblage, yet the site is quite distant to viable geologic sources of obsidian. XRF analysis of obsidian tools and debitage sampled throughout the site display a pettern of source use through time that can be used to investigate land use patterns and interactions within and outside the Bonneville basic of northwestern Utah. Results of this sourcing investigation indicate a broad geographic range of obsidian procurement through time with a heavy focus on use of the Brpwns Bench geochemical group.

Abstract: A study of obsidian procurement in Washington County, Utah, allows an examination of mobility and cultural interaction. on the fringes of the Great Basin. Presented here are XRF data from 58 pre-contact archaeological sites ranging from early Archaic to ca. 600 B.P. The wide temporal range provides an excellent opportunity to evaluate shifting obsidian procurement strategies through time. Source provenance datashow great similarity to assemblages from elsewhere in the eastern Great Basin, but distant sources in these assemblages may help to illustrate the area's connections to other parts of the region. [Email: aestevenson13@hotmail.com]

All back issues of the IAOS Bulletin dating from No. 1 (1989) to present are available as Adobe Acrobat downloads. Click the PDF button on the left to head over to the download index page.