Variations of stable isotopic ratios of carbon (C-13/C-12) and oxygen (O-18/O-16) were investigated in modern shells of two species of Rabdotus land snails (R. dealbatus and R. alternatus) in the southern Great Plains. Geographic variation in relation to climate and vegetation, microgeographic variation, variability among individuals, and detailed records of seasonal variations within individual shells were studied. Stable carbon isotopic ratios in shell carbonate are primarily a function of the isotopic composition of the diet of the snails, as represented by the isotopic composition of shell organic matter. This in turn reflects the presence or absence of CAM (Crassulacean Acid Metabolism) or C-4 plants. Vegetation density may have a small effect on the carbon isotope ratios. Microgeographic variation (samples within 25 to 300 m) is greater than that seen across different climatic regions and points to very local control of isotopic variations, predominantly related to vegetation. Seasonal variations, as assessed through serial analysis of individual shells (up to 35 samples per shell), may provide a means for distinguishing between isotopic influences of perennial CAM vs. annual C-4 plants. Carbon isotopic variations in time-series of shells from a site provide a means of reconstructing temporal changes in environment and climate.Oxygen isotopic values of shell carbonate are uniform across the region and also show no significant microgeographic variation. The oxygen isotopic composition appears to be mainly a function of the rainwater isotopic composition, with no direct influence of rainfall amount or evaporative effects. The delta(18)O values are only 2parts per thousand enriched relative to estimated equilibrium with rainwater. Variability is low (SD of 0.8parts per thousand among sites), so the isotopic composition of fossil Rabdotus shells can provide a precise record of changes in the isotopic composition of rain over time. Copyright (C) 2002 Elsevier Science Inc.

Stable carbon isotope ratios of shell carbonate and shell organic matter from land snails (Rabdotus alternatus) from Hinds Cave, Texas, are used to reconstruct the climate history of the drier western part of the southern Great Plains (present mean annual rainfall of 400 mm) over the last ca. 5000 yr. AMS radiocarbon analyses of four individual shells from each of two strata indicate that there are no problems of reworking or age mixtures within strata. However, burning is evident in many shells. Amino acid composition and racemization were used to identify shells that had been significantly heated and these were rejected for isotopic analysis because of possible alteration of the isotopic signal. Fourteen samples of snails from Hinds Cave, each consisting of 2–6 individual shells from the same provenience, were radiocarbon dated by AMS and analyzed for stable carbon isotopes. In addition, a sample collected alive ca. AD 1890 from a nearby site, was analyzed to represent modern conditions. The shells show no decrease in organic content with age, indicating good preservation of shell organic matter. Both the organic and carbonate isotope values show similar temporal trends. The oldest samples (4100–4600 cal yr BP) are relatively depleted in 13C. Maximum δ13C values are reached at ca. 3500 cal yr BP. Thereafter there is a regular depletion in 13C, with the recent sample showing the lowest δ13C value. The change in the isotopic values over time is quite large (range of 4.5‰ for organic matter) and indicates substantial climatic changes. The variations in isotopic values are interpreted as resulting primarily from changes in moisture conditions, affecting the abundance of drought-adapted CAM (Crassulacean acid metabolism) plant species (enriched in 13C). Thus relatively moist mid-Holocene conditions are indicated, with increasingly dry conditions reaching a maximum at ca. 3500 cal yr BP, followed by progressively moister conditions through the late Holocene.

Accelerator mass spectrometric (AMS) radiocarbon analyses of live-collected, prebomb samples of shell carbonates of the land snails Rabdotus dealbatus and R. alternatus from Texas were carried out to quantify the characteristic age anomalies of land snails from limestone areas. Age anomalies are similar for the two species; they average +700 yr and vary by ±180 yr (1σ) among samples. Serial analysis of 1 shell reveals a significant ontogenetic trend in 14 C age anomalies, with older apparent ages (up to 1200 yr) in the apical part of the shell and younger and uniform ages in the last whorl. No trend in age anomalies was found across a broad range of rainfall conditions (from 300 to 1000 mm mean annual rainfall).

GeoarchaeologyVolume 11, Issue 3 p. 189-213 Assessment of integrity and geochronology of archaeological sites using amino acid racemization in land snail shells: Examples from central Texas G. Lain Ellis, Corresponding Author G. Lain Ellis Texas Historical Commission, P.O. Box 12276, Austin, Texas 78711Texas Historical Commission, P.O. Box 12276, Austin, Texas 78711Search for more papers by this authorGlenn A. Goodfriend, Glenn A. Goodfriend Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road, N.W., Washington, DC 20015-1305Search for more papers by this authorJames T. Abbott, James T. Abbott TRC-Mariah Associates, Inc., 3939 Bee Caves Road, Suite C-100, Austin, Texas 78746-6429Search for more papers by this authorP. E. Hare, P. E. Hare Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road, N.W., Washington, DC 20015-1305Search for more papers by this authorDavid W. Von Endt, David W. Von Endt Conservation Analytical Laboratory, Smithsonian Institution, 4210 Silver Hill Road, Suitland, Maryland 20746Search for more papers by this author G. Lain Ellis, Corresponding Author G. Lain Ellis Texas Historical Commission, P.O. Box 12276, Austin, Texas 78711Texas Historical Commission, P.O. Box 12276, Austin, Texas 78711Search for more papers by this authorGlenn A. Goodfriend, Glenn A. Goodfriend Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road, N.W., Washington, DC 20015-1305Search for more papers by this authorJames T. Abbott, James T. Abbott TRC-Mariah Associates, Inc., 3939 Bee Caves Road, Suite C-100, Austin, Texas 78746-6429Search for more papers by this authorP. E. Hare, P. E. Hare Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road, N.W., Washington, DC 20015-1305Search for more papers by this authorDavid W. Von Endt, David W. Von Endt Conservation Analytical Laboratory, Smithsonian Institution, 4210 Silver Hill Road, Suitland, Maryland 20746Search for more papers by this author First published: May 1996 https://doi.org/10.1002/(SICI)1520-6548(199605)11:3<189::AID-GEA1>3.0.CO;2-%23Citations: 12AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Abstract Detailed racemization analyses were carried out on samples of the land snail Rabdotus mooreanus from archaeological sites at Fort Hood, in central Texas. D-alloisoleucine/L-isoleucine (A/I) values were determined for 260 individual shells from 29 proveniences, including sites in alluvium, colluvium, and rockshelters, as well as burned rock middens. A/I values show a good correlation with radiocarbon age, and so provide reasonably precise estimates of ages. Analyses indicate the presence of redeposited material in a large number of proveniences. These result from sedimentary processes involved in burial of the sites as well as from later disturbance (aboriginal or recent) of site stratigraphy. Because amino acid racemization analyses are relatively easy to carry out, this method lends itself to very detailed chronostratigraphic analyses of archaeological sites, thus permitting assessment of site integrity and assisting in the interpretation of site formation processes. © 1996 John Wiley & Sons, Inc. References Abbott, J. T. (1994). Natural Environment. In W. N. Trierweiler, Ed., Archeological Investigations on 571 Prehistoric Sites at Fort Hood, Bell and Coryell Counties, Texas, pp. 7–38. Archeological Resource Management Series, Research Report No. 31. Fort Hood, Texas: U.S. Army. Google Scholar Bada, J. L., and Helfman, P. M. (1975). Amino Acid Racemization Dating of Fossil Bone. World Archaeology 7, 160–173. 10.1080/00438243.1975.9979630 CASPubMedWeb of Science®Google Scholar Bada, J. L., Gillespie, R., Gowlett, J. A. J., and Hedges, R. E. M. (1984). Accelerator Mass Spectrometry Radiocarbon Ages of Amino Acid Extracts from California Palaeoindian Skeletons. Nature 312, 442–444. 10.1038/312442a0 CASPubMedWeb of Science®Google Scholar Binford, L. R. (1982). The Archaeology of Place. Journal of Anthropological Archeology 1, 5–31. 10.1016/0278-4165(82)90006-X Google Scholar Butzer, K. W. (1982). Archaeology as Human Ecology: Method and Theory for a Contextual Approach. Cambridge: Cambridge University Press. 10.1017/CBO9780511558245 Google Scholar Brooks, A. S., Hare, P. E., Kokis, J. E., Miller, G. H., Ernst, R. D., and Wendorf, F. (1990). Dating Pleistocene Archeological Sites by Protein Diagenesis in Ostrich Eggshell. Science 248, 60–64. 10.1126/science.248.4951.60 CASPubMedWeb of Science®Google Scholar Ellis, G. L., and Goodfriend, G. A. (1994). Chronometric and Site-Formation Studies Using Land Snail Shells: Preliminary Results. In W. N. Trierweiler, Ed., Archeological Investigations on 571 Prehistoric Sites at Fort Hood, Bell and Coryell Counties, Texas, pp. 183–201. Archeological Resource Management Series, Research Report No. 31. Fort Hood, Texas: U.S. Army. Web of Science®Google Scholar Elster, H., Gil-Av, E., and Weiner, S. (1991). Amino Acid Racemization of Fossil Bone. Journal of Archaeological Science 18, 605–617. 10.1016/0305-4403(91)90055-T Web of Science®Google Scholar Ferring, R. C. (1986). Rates of Fluvial Sedimentation: Implications for Archaeological Variability. Geoarchaeology 1, 259–274. 10.1002/gea.3340010303 Google Scholar Goodfriend, G. A. (1987a). Radiocarbon Age Anomalies in Shell Carbonate of Land Snails from Semi-Arid Areas. Radiocarbon 29, 159–167. 10.1017/S0033822200056915 CASWeb of Science®Google Scholar Goodfriend, G. A. (1987b). Chronostratigraphic Studies of Sediments in the Negev Desert, Using Amino Acid Epimerization Analysis of Land Snail Shells. Quaternary Research 28, 374–392. 10.1016/0033-5894(87)90005-6 CASWeb of Science®Google Scholar Goodfriend, G. A. (1987c). Evaluation of Amino-Acid Racemization/Epimerization Dating Using Radiocarbon-Dated Fossil Land Snail Shells. Geology 15, 698–700. 10.1130/0091-7613(1987)15<698:EOARDU>2.0.CO;2 CASWeb of Science®Google Scholar Goodfriend, G. A. (1991). Patterns of Racemization and Epimerization of Amino Acids in Land Snail Shells over the Course of the Holocene. Geochimica et Cosmochimica Acta 55, 293–302. 10.1016/0016-7037(91)90418-5 CASWeb of Science®Google Scholar Goodfriend, G. A. (1992). The Use of Land Snail Shells in Paleoenvironmental Reconstruction. Quaternary Science Reviews 11, 665–685. 10.1016/0277-3791(92)90076-K Web of Science®Google Scholar Goodfriend, G. A., and Hood, D. G. (1983). Carbon Isotope Analysis of Land Snail Shells: Implications for Carbon Sources and Radiocarbon Dating. Radiocarbon 25, 810–830. 10.1017/S0033822200006226 Web of Science®Google Scholar Goodfriend, G. A., and Mitterer, R. M. (1993). A 45,000-Yr Record of a Tropical Lowland Biota: The Land Snail Fauna from Cave Sediments at Coco Ree, Jamaica. Geological Society of America Bulletin 105, 18–29. 10.1130/0016-7606(1993)105<0018:AYROAT>2.3.CO;2 Web of Science®Google Scholar Goodfriend, G. A., Cameron, R. A. D., and Cook, L. M. (1994). Fossil Evidence of Human Impact on the Land Snail Fauna of Madeira. Journal of Biogeography 21, 309–320. 10.2307/2845532 Web of Science®Google Scholar Hare, P., St. John, P. A., and Engel, M. (1985). Ion-Exchange Separation of Amino Acids. In G. C. Barrett, Ed., Chemistry and Biochemistry of the Amino Acids, pp. 415–425. London: Chapman and Hall. 10.1007/978-94-009-4832-7_14 Google Scholar Hare, P. E., Goodfriend, G. A., Brooks, A. S., Kokis, J. E., and Von Endt, D. W. (1993). Chemical Clocks and Thermometers: Diagenetic Reactions of Amino Acids in Fossils. Yearbook of the Carnegie Institution of Washington 92, 80–85. Google Scholar Howard, M. A. (1991). Burned Rock Midden Excavations, Hearths and Botanical Remains. In T. R. Hester, Ed., The Burned Rock Middens of Texas: An Archeological Symposium, pp. 45–69. Studies in Archeology No. 13. Austin: Texas Archeological Research Laboratory, University of Texas at Austin. Google Scholar Johnson, B. J., and Miller, G. H. (in press). Archaeological Applications of Amino Acid Racemization Dating: A Review. Archaeometry. Google Scholar Lajoie, K. D., Peterson, E., and Gerow, B. A. (1980). Amino Acid Bone Dating: A Feasibility Study, South San Francisco Bay Region, California. In P. E. Hare, T. C. Hoering, and K. King, Eds., Biogeochemistry of Amino Acids, pp. 193–201. New York: John Wiley & Sons. Google Scholar Miller, G. H., and Brigham-Grette, J. (1989). Amino Acid Geochronology: Resolution and Precision in Carbonate Fossils. Quaternary International 1, 111–128. 10.1016/1040-6182(89)90011-6 Google Scholar Miller, G. H., Beaumont, P. B., Tull, A. J. T., and Johnson, B. (1992). Pleistocene Geochronology and Palaeothermometry from Protein Diagenesis in Ostrich Eggshells: Implications for the Evolution of Modern Humans. Philosophical Transactions of the Royal Society of London, B 337, 149–157. 10.1098/rstb.1992.0092 CASPubMedWeb of Science®Google Scholar Quigg, J. M., and Ellis, G. L. (1994). Burned Rock Mound Chronometric Investigations. In W. N. Trierweiler, Ed., Archeological Investigations on 571 Prehistoric Sites at Fort Hood, Bell and Coryell Counties, Texas, pp. 205–274. Archeological Resource Management Series, Research Report No. 31. Fort Hood, Texas: U.S. Army. Google Scholar Rosen, S. A., and Goodfriend, G. A. (1993). An Early Date for Gaza Ware from the Northern Negev. Palestine Exploration Quarterly 125, 143–148. 10.1179/peq.1993.125.2.143 Google Scholar Schiffer, M. B. (1987). Formation Processes of the Archaeological Record. Albuquerque: University of New Mexico Press. Google Scholar Stuiver, M., and Pearson, G. W. (1986). High-Precision Calibration of the Radiocarbon Time Scale, AD 1950–500 BC. Radiocarbon 28, 805–838. 10.1017/S0033822200060161 CASWeb of Science®Google Scholar Stuiver, M., and Reimer, P. J. (1993). Extended 14C Data Base and Revised CALIB 3.0 14C Age Calibration Program. Radiocarbon 35, 215–230. 10.1017/S0033822200013904 Web of Science®Google Scholar Taylor, R. E., Ennis, P. J., Slota, P. J. Jr., and Payen, L. A. (1989). Non-Age-Related Variations in Aspartic Acid Racemization in Bone from a Radiocarbon-Dated Late Holocene Archaeological Site. Radiocarbon 31, 1048–1056. Web of Science®Google Scholar W. N. Trierweiler, Ed. (1994). Archeological Investigations on 571 Prehistoric Sites at Fort Hood, Bell and Coryell Counties, Texas. Archeological Resource Management Series, Research Report No. 31. Fort Hood, Texas: U.S. Army. Google Scholar Wylie, A. (1992). The Interplay of Evidential Constraints and Political Interests: Recent Archaeological Research on Gender. American Antiquity 57, 15–35. 10.2307/2694833 Web of Science®Google Scholar Citing Literature Volume11, Issue3May 1996Pages 189-213 ReferencesRelatedInformation

: Federal installations must comply with the National Historic Preservation Act (NHPA) which, in part, requires cultural resources to he evaluated in terms of their eligibility for the National Register of Historic Places. Currently, no generalized model exists to guide such evaluation. This study attempts to develop a generalized model of evaluation that will produce meaningful, replicable, and defensible evaluations of scientific significance for large numbers of cultural resource properties. A Cultural Resources Management (CRM) program needs a method to determine what sites merit protection under the NHPA. This study proposes prefacing any such determination effort with a complex, detailed research design specific to the archaeological data needs of the area. Site significance can then be determined in light of the data needed to answer regional research questions. The goal of the site inventory and testing phases is to find out whether a site has the needed data types. Alternative field tactics for inventory and testing are also discussed in this study. The study presents a detailed case study from Fort Hood, Texas, illustrating how a Federal CRM program can go awry, how to fix it, and more importantly, how to design a sound management program from the ground up.

American AnthropologistVolume 93, Issue 1 p. 125-137 Cultural and Landscape Influences on Tucson Basin Hohokam Settlement G. Lain Ellis, G. Lain Ellis Department of Anthropology Texas A & M UniversitySearch for more papers by this authorMichael R. Waters, Michael R. Waters Department of Anthropology Texas A & M UniversitySearch for more papers by this author G. Lain Ellis, G. Lain Ellis Department of Anthropology Texas A & M UniversitySearch for more papers by this authorMichael R. Waters, Michael R. Waters Department of Anthropology Texas A & M UniversitySearch for more papers by this author First published: March 1991 https://doi.org/10.1525/aa.1991.93.1.02a00070AboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume93, Issue1March 1991Pages 125-137 RelatedInformation