University of Montana ScholarWorks at University of Montana Graduate Student Theses, Dissertations, & Professional Papers Graduate School 1980 Geoarchaeology of a rockshelter : site 5 ME 82 Mesa County Colorado Barbara A. Till The University of Montana Follow this and additional works at: https://scholarworks.umt.edu/etd Let us know how access to this document benefits ou.y Recommended Citation Till, Barbara A., "Geoarchaeology of a rockshelter : site 5 ME 82 Mesa County Colorado" (1980). Graduate Student Theses, Dissertations, & Professional Papers. 7362. https://scholarworks.umt.edu/etd/7362 This Thesis is brought to you for free and open access by the Graduate School at ScholarWorks at University of Montana. It has been accepted for inclusion in Graduate Student Theses, Dissertations, & Professional Papers by an authorized administrator of ScholarWorks at University of Montana. For more information, please contact [email protected]. COPYRIGHT ACT OF 1976 Th is is an unpublished manuscript in which copyright sub ­ s is t s . Any further reprinting of its contents must be approved BY THE AUTHOR. MANSFIELD Library University of Montana Date: * ^8 0______ GEOARCHAEOLOGY OF A ROCKSHELTER— SITE 5 ME 82, MESA COUNTY, COLORADO By Barbara A. T ill B.A., Fort Lewis College, 1975 Presented in partial fulfillment of the requirements for the degree of Master of Arts UNIVERSITY OF MONTANA 1980 Approved by: Chairman, Board of Examines Dean, Graduate School Date UMI Number: EP38163 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. UMT Oi&wKWion Publishing UMI EP38163 Published by ProQuest LLC (2013). Copyright in the Dissertation held by the Author. 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Box 1346 Ann Arbor, Ml 48106 -1346 TABLE OF CONTENTS Page Abstract ............................................................................................................ ü Acknowledgements 11 i List of Figures 1 v List of Tables ............................................................................................. v List of Plates ......................................................................... vi Chapter 1 — Introduction ........................................................................ 1 Chapter 2 — Descriptionof the Area ................................................. 6 Physiography Legal Location/Access Climate Soils Vegetation W ildlife Chapter 3 - - - Archaeology .......................................................... 11 Regional Site-specific Site stratigraphy Chapter 4 — Geology ................................................................................. 20 Cretaceous Tertiary Quaternary Site-specific Chapter 5 — Methodology............................................................................. 28 Sampling Grain-size Analysis Scanning Electron Microscopy X-ray Diffraction of Clay Minerals Chapter 6 — Results and Interpretation ........................ 36 Landforms Grain-size Analysis Scanning Electron Microscopy X-ray Diffraction of Clay Minerals Chapter 7 — Summary and Conclusions ----- 48 References Cited ................... 57 Appendix...................................................................................................................... 65 ABSTRACT T i l l , Barbara A., M.A., June 1980 Anthropology Geoarchaeology of a Rockshelter— Site 5 ME 82, Mesa County, Colorado (85 pp.) Director: Dee C. Taylor Site 5 ME 82, a prehistoric rockshelter, is located on the Colorado Plateau in west central Colorado. Occupied ca. 5000-600 B.C., this Archaic-period site has yielded few artifacts. Yet 5 ME 82 provides information relating to environmental conditions met with by the site's prehistoric inhabitants. A geoarchaeological study of 5 ME 82 was undertaken in order to recover information regarding the site's paleoenvironment. This study included: (1) fie ld observations of geomorphic units in the site area, and (2) laboratory analysis of rockshelter sediments. The la tte r involved use of the following geoarchaeological procedures: grain-size analysis, scanning electron microscopy, and X-Ray diffraction of clay minerals. Analysis suggests that the paleoenvironment at the site during in itia l occupation was more humid than the present climate of the area. However, through time increasingly arid conditions prevailed. Based on geo­ archaeological interpretations, trends in the site's pollen profile and lith ic assemblage are predicted. 11 ACKNOWLEDGEMENTS A number of individuals and organizations helped make this study possible. I would like to extend my thanks to the Bureau of Land Management and Centuries Research, Inc. for financial assistance; to Alan D. Reed and Paul R. Nickens of Nickens and Associates, formerly of Centuries Research, Inc., for fie ld data, assistance, and encouragement; to Michael Joyce and Gray Thompson, Department of Geology, University of Montana, for help with clay mineral analysis; and to Dr. C.A. Speer, Department of Microbiology, University of Montana, for permission to use the Electron Microscopy Laboratory. Warmest thanks are extended to J.N. Moore, Department of Geology, University of Montana, whose encouragement, instruction, and friendship are deeply appreciated. I would like to thank my thesis committee chairman. Dr. Dee C. Taylor, and committee members Dr. Frederick C. Munday and Dr. Johnnie N. Moore for their time and assistance. m LIST OF FIGURES Page Fig, 1 — Areal Map ...................................................................... 7 Fig. 2 — Stratigraphie profile, west wall ............................... 18 Fig. 3 — Sketch Map — Plan view of site area ......................... 37 Fig. 4 Sketch Map — Summary of Geologic Events at 5 ME 82 40 Figs. 5 - 25 — Grain-size Distribution Histograms ........... 65-85 IV LIST OF TABLES Page Table 1 — Normal Temperature and Precipitation for the period 1931-1960 9 Table 2 — Radiocarbon dates ............................................................. 19 Table 3 — List of Analyzed Samples ............................................... 29 Table 4 — Correlation of sieves, millimeters, phi, and Wentworth size classes .......................................... 32 LIST OF PLATES Page Plate 1 —- Site 5 ME 82 ...................................................................... vii Plates 2 M 9 — Electron micrographs of quartz grains 44-45 VI — ' H % 'TT. Plate 1 Site 5 ME 82 v i i Chapter 1 : INTRODUCTION Site 5 ME 82, a prehistoric rockshelter, is located on the Colorado Plateau in west central Colorado. Diagnostic artifacts as well as the range of radiocarbon dates (ca. 5000 to 600 B.C.) indicate Archaic cultural affiliation. The rockshelter was partially excavated in May and early June 1979, by Centuries Research, Montrose, Colorado, under contract to the U.S. Department of the In terio r, Bureau of Land Manage­ ment. The site had been previously vandalized, hence the BLM wanted to test the site before more vandalism occurred. Three other smaller rock­ shelter sites within the same area have been almost to tally destroyed by pothunters. While relatively few artifacts were recovered, 5 ME 32 and similar small sites can yield significant amounts of information pertinent to archaeological interpretation. Much of this information can be obtained through interdisciplinary studies. While employed by Centuries Research during the summer of 1979, I undertook a geoarchaeological study of the site. I visited the rockshelter in late June and in July, following test excavations, in order to obtain data for this study. Geoarchaeology, the "resolution of geology-related problems in archaeology" (Hassan 1979: 267) attempts to answer archaeological questions through the use of geological techniques. My primary interest 1 in the rockshelter was in testing and applying geoarchaeological techniques in order to recover information regarding the paleoenvironment at the site. Thus, the data would address questions about environmental change or continuity and potentially allow inferences to be made about human ecological adaptation, regional culture history, and ultimately man/land relationships. The geoarchaeological study I carried out was two-fold: (1) analysis of rockshelter sediments, and (2) analysis of the landforms or geo­ morphology near the site. I was particularly interested in applying geoarchaeological methods to a rockshelter s ite , because not only does a cave or rockshelter form a natural sediment trap (Collcutt 1979: 290), but the sedimentary accumulation in such a site is more easily preserved than that in an open site. Precedents exist for this type of study, however the majority of these geoarchaeological cave studies have been undertaken on Old World sites. 5 ME 82 differs in several important ways from these sites as well as from most New World sites where geoarchaeological techniques have been utilized. These differences include: (1) The parent rock type of 5 ME 82 is sandstone rather than limestone (the most common material in which caves are formed). This point is quite significant, because the majority of geoarchaeological cave studies are based on examination of limestone