Obsidian Source Provenance Studies in the Hohokam CoreNew Perspectives from the Middle Gila River, South-Central Arizona

Obsidian Source Provenance Studies in the Hohokam CoreNew Perspectives from the Middle Gila River, South-Central Arizona

1Gila River Indian Community, Cultural Resource Management Program

Chris Loendorf1, J. Andrew Darling1, and M. Steven Shackley2Chris Loendorf1, J. Andrew Darling1, and M. Steven Shackley2

Obsidian source provenance studies are a staple of archaeometricresearch and have been a major contributor to anthropological statements regarding source utilization and raw material distribution. Recent x-ray fluorescence (XRF) analyses of obsidian artifacts from sitesin the Gila River Indian Community and elsewhere have amassed trace-element a database that includes over 1600 obsidian artifacts. Provenance expectations based on regional studies are evaluated against findings from excavated sites in the west end (Estrella Mountain foothills, ELXP) and east-central (Santan, GR-522) areas of the reservation. Results demonstrate the advantages of large datasets and the comparative potential of regional and excavation-based research methodologies

Obsidian projectile points from the Tonto Basin, collected during the Roosevelt Platform Mound Study

Obsidian projectile points from the Tonto Basin, collected during the Roosevelt Platform Mound Study

Projectile points from the Gila River Indian Community

Projectile points from the Gila River Indian Community

Trace element analyses were performed in the Archaeological XRF Laboratory, Department of Earth and Planetary Sciences, University of California, Berkeley, using a Spectrace/ThermoNoranTM QuanX energy dispersive x-ray fluorescence spectrometer. The spectrometer is equipped with an air cooled Cu x-ray target with a 125 micron Be window, an x-ray generator that operates from 4-50 kV/0.02-2.0 mA at 0.02 increments, using an IBM PC based microprocessor and WinTraceTM reduction software. X -ray intensity Kα-line data were generated for elements including Ti, Mn, FeT, Th, Rb, Sr, Y, Zr, and Nb. Trace element intensities were converted to concentration estimates by employing a least-squares calibration based on the analysis of international rock standards certified by the National Institute of Standards and Technology (NIST), the US. Geological Survey (USGS), Canadian Centre for Mineral and Energy Technology, and the Centre de Recherches Pétrographiques et Géochimiques in France (Govindaraju 1994, see also Shackley 1995, 2005; Hughes and Smith 1993). In addition, the values for Ni, Cu, Zn, Th, and Gawere measured, but these are rarely useful in discriminating glass sources and are not generally reported.

IntroductionIntroduction

Obsidian Trace Element AnalysisObsidian Trace Element Analysis

Archaeological Obsidian StudiesArchaeological Obsidian Studies

Study of the intersocietal movement of goods is one of the primary methods archaeologists employ to identify prehistoric interaction systems at different scales from the local to the regional. Exchange patterns reflect community and regional economic, ideological, and political interrelationships. These socioeconomic relationships involve many factors including value, the number and type of transactions between the source and the consumer, regional distribution, competition, and “the social and cultural meaning of the goods” (Kooyman 2000:140). Archaeologists have developed ways to examine exchange by analyzing goods such as obsidian, which has properties that are ideally suited for the study of socioeconomic interaction patterns in central Arizona from AD 500-1450. First, obsidian is a desirable, but not ubiquitous, raw material for retouched tool manufacture. Second, obsidian sources are generally localized deposits that in most instances are also abundant. Third, obsidian does not occur within the core area of Hohokam habitation in the Phoenix and Tonto Basins, but sources are present to the north, south, east, and west. Fourth, obsidian has geochemical and physical properties that allow source areas to be objectively defined with a high degree of precision (Clark 1989). Consequently, diachronic and synchronic patterning in obsidian acquisition can be employed to address economic, political, and ideological aspects of Hohokam society.

Study of the intersocietal movement of goods is one of the primary methods archaeologists employ to identify prehistoric interaction systems at different scales from the local to the regional. Exchange patterns reflect community and regional economic, ideological, and political interrelationships. These socioeconomic relationships involve many factors including value, the number and type of transactions between the source and the consumer, regional distribution, competition, and “the social and cultural meaning of the goods” (Kooyman 2000:140). Archaeologists have developed ways to examine exchange by analyzing goods such as obsidian, which has properties that are ideally suited for the study of socioeconomic interaction patterns in central Arizona from AD 500-1450. First, obsidian is a desirable, but not ubiquitous, raw material for retouched tool manufacture. Second, obsidian sources are generally localized deposits that in most instances are also abundant. Third, obsidian does not occur within the core area of Hohokam habitation in the Phoenix and Tonto Basins, but sources are present to the north, south, east, and west. Fourth, obsidian has geochemical and physical properties that allow source areas to be objectively defined with a high degree of precision (Clark 1989). Consequently, diachronic and synchronic patterning in obsidian acquisition can be employed to address economic, political, and ideological aspects of Hohokam society.

Obsidian Projectile Points From The Gila River Indian Community,Collected During the Pima-Maricopa Irrigation Project

Obsidian Projectile Points From The Gila River Indian Community,Collected During the Pima-Maricopa Irrigation Project

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VultureSuperiorSauceda MtsMule Cr-AC/MMLos Vidrios*Government Mtn*Government MtnBlue/SF River

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VultureSuperiorSauceda MtsMule Cr-AC/MMLos Vidrios*Government Mtn*Government MtnBlue/SF River

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Rb versus Zr biplot of GR-522 data. Asterisked data are those outside the range of source standards

Rb versus Zr biplot of GR-522 data. Asterisked data are those outside the range of source standards

Hohokam Obsidian UseHohokam Obsidian Use

Collection Period Tank

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K-Means Cluster

Sample Size

Snaketown Pre-Classic 5 2 2 22 1 60 2 1 0 3 299GR-522 Locus D Pre-Classic 3 13 15 51 18 14 3 39GR-522 Locus A Classic 2 4 61 20 2 12 14 1 51ELXP Classic? 1 7 5 3 4 63 5 8 1 15 1 76Rowley Classic 47 30 23 29 5 43Pueblo Grande Classic 1 4 4 27 22 30 10 3 31 5 220Los Colinas Pre-Classic 4 2 4 26 38 10 10 2 4 36 2 50Casa Grande Classic 1 29 46 7 14 2 42 4 137Grewe Pre-Classic 1 1 95 1 2 45 3 137Palo Verde Pre-Classic 2 55 31 11 1 64 2 122Gatlin Pre-Classic 3 1 4 85 7 73 1 75Brady Wash Classic 3 7 4 79 3 1 1 86 1 67Tonto Arm Early Classic 5 90 2 3 93 3 11Tonto Arm Late Classic 38 20 6 4 32 93 4 80Salt Arm Early Classic 13 13 13 64 97 3 54Salt Arm Late Classic 3 33 11 15 9 26 3 97 4 45Marana Classic 6 85 4 1 3 1 124 1 152

Pre-Classic GRIC Pre-Classic 11 55 33 N/A N/A 9Classic GRIC Classic 8 67 8 8 8 N/A N/A 12Historic GRIC Historic 5 9 76 9 N/A N/A 21

Pre-Classic Avg. Pre-Classic 1 1 1 13 14 3 27 34 4 N/A N/A 731Classic Average Classic 1 9 13 1 42 22 1 7 3 N/A N/A 948Total Average Both 1 11 13 2 34 28 1 4 4 N/A N/A 1679

(West) Obsidian Source (East)

P-MIP Survey Data

All Data

Hohokam Obsidian Source Proportions for Collections with More than 40 Sourced Artifacts (source data from, Loendorf et al. 2004; Marshall 2002, Peterson et al. 1997; Shackley & Bayman 2006; Rice et al. 1998). Sites are Organized based on the Distance from Snaketown. Cluster Assignments for a K-Means Non-Hierarchical Cluster Analysis are also Reported.

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VultureSuperiorSauceda MtsMule Cr-AC/MMLos VidriosGovernment MtnBlue/SF River

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VultureSuperiorSauceda MtsMule Cr-AC/MMLos VidriosGovernment MtnBlue/SF River

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Sr versus Zr biplot of GR-522 data collapsing questionable source assignments into confident assignments from above figure.

Sr versus Zr biplot of GR-522 data collapsing questionable source assignments into confident assignments from above figure.

Distanse from Sauceda Source in KM

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Brady Wash

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Palo Verde Grewe

Casa Grande

Los Colinas

Pueblo Grande Rowley

ELXPGR-522 A

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Distanse from Sauceda Source in KM

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ELXPGR-522 A

GR-522 D

Snaketown

Sauceda Obsidian was the most common type used by the Hohokam, and its proportion in assemblages is very weakly correlated (Person Correlation = -0.03) with distance from the source. Sauceda use differs at adjacent Pre-Classic and Classic Period Habitation Areas (e.g., GR-522 A and GR-522 D), with greater use of Sauceda obsidian occurring during the Classic Period.

Obsidian proportions for some types do exhibit falloff relationships within regions. For example in the Gila River Community, Vulturefrequencies falloff west to east and Vulture is located to the west. In contrast, Superior frequencies east to west and Superior is located to the east.

Obsidian Source and Archaeological Site Locations

Obsidian Source and Archaeological Site Locations

Cluster analysis (Squared-Euclidian measure and Ward’s method) dendrogram for Classic period obsidian. At the two cluster level, Salt River basin sites are in one cluster, whereas sites in the Gila River basin are in the second. Although Gila sites such as GR-522 are less than 35 KM from Pueblo Grande, obsidian proportions differ. At the same time, the Tonto Basin is more than 80 KM away from Pueblo Grande, yet it has more similar obsidian proportions.

Site 1 5 10 15 20 25

MaranaBrady WashEXLPGR-522 ACasa Grande

Tonto ArmSalt ArmPueblo GrandeRowley

Approximate Rescaled Cluster Combination Distance

Clark, J. E. 1989 Obsidian: The Primary Mesoamerican Sources. In La Obsidiana en Mesoamerica, Pp. 299-319. Edited by M. Gaziola and J. E. Clark. Colección Cientifica, Serie: Arqueología, 176, Instituto Nacional de Antropología e Historia, México.

Govindaraju, K.1994 Compilation of Working Values and Sample Description for 383 Geostandards. Geostandards Newsletter 18 (special issue).Hughes, R. E., and Smith, R.L.

1993 Archaeology, Geology, and Geochemistry in Obsidian Provenance Studies. In Stein, J.K. and Linse, A.R. eds., Scale on Archaeological and Geoscientific Perspectives, edited by, pp. 79-91. Geological Society of America Special Paper 283, Boulder

Kooyman, B.P2000 Understanding Stone Tools and Archaeological Sites. University of Calgary Press, Alberta, Canada.Loendorf, Chris, J. Andrew Darling, and M. Steven Shackley

2004 Hohokam Obsidian Procurement and Distribution in the Middle Gila River Valley: A Regional Approach. A paper presented at the Inaugural Symposium of the Archaeological Sciences of the Americas, Tucson, Arizona.

Marshall, J. T.2002 Obsidian and the Northern Periphery: Tool Manufacture, Source Distribution, and Patterns of Interaction. In Phoenix Basin to Perry Mesa: Rethinking the “NorthernPeriphery”.Arizona Archaeologist Number 34, Edited by Mark R. Hackbarth, Kelly Hays-Gilpin, and Lynn Neal. Arizona Archaeological Society, Phoenix.

Peterson, J., D. R. Mitchell, and M. S. Shackley1997 The Social and Economic Contexts of Lithic Procurement: Obsidian fomr Classic-Period Hohokam Site. American Antiquity, 62(2), pp. 231-259.

Rice, G. E., A. Simon, and C. Loendorf1998 Production and Exchange of Economic Goods. In A Synthesis of Tonto Basin Prehistory: The Roosevelt Archaeology Studies, 1989 to 1998, edited by G. E. Rice, pp. 105-130. Roosevelt Monograph Series 12 and Anthropological Field Studies 41, Arizona State University.

Shackley, M. S.1995 Sources of Archaeological Obsidian in the Greater American Southwest: An Update and Quantitative Analysis. American Antiquity 60(3):531-551.2005 Obsidian: Geology and Archaeology in the North American Southwest. University of Arizona Press, Tucson.

Shackley, M. Steven and James M. Bayman2006 “Obsidian Source Provenance, Projectile Point Morphology and Sacaton Phase Hohokam Cultural Identity.” In A Snaketown Retrospective, edited by P. Fish and S. Fish. University of Arizona Press, Tucson.

References Cited

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For the Hohokam of Central Arizona, direction of the source has a greater effect than absolute distance on raw material utilization. Further, obsidian commonly arrived at sites in unreduced form. It appears that prehistoric people in the Salt Basin, Middle Gila, and the two arms of the Tonto Basin maintained different trade contacts. Obsidian acquisition patterns suggest that the strongest socioeconomic ties among communities were between those located on the same waterways. Variation in obsidian use among these areas supports the argument that the Classic period Hohokam were not a politically centralized oreconomically integrated entity. Data suggest that by the Late Classic, little obsidian was transferred between adjacent subregions. Instead communities of sites received most of their obsidian from distant areas in different directions. Use of the closest source, Superior, decreased over time from the pre-Classic to the Classic period. While Saucedaobsidian, which is located to the southwest of the core area, became the main obsidian supply by the Late Classic and this trend continued into the Historic period. This continuity of trends between the Classic and Historic periods is an example of the link between the Hohokam and the Akimel O’odham (Pima), who live in the area today.

Conclusions

This research was conducted by the GRIC CRMP, in collaboration with the Bureau of Reclamation-Pima-Maricopa Irrigation Project (BOR P-MIP) under the Tribal Self Governance Act of 1994 [P.L. 103-413]. We also wish to thank William Self Associates, Inc. Obsidian sourcing was conducted as part of the Santan Data Recovery Project (P-MIP) and the SFPP East Line Expansion Project.