the sample. In this case, all seven analyses do fall on or close to the line. The slope of this line and the measured 234U/238U

ratio are then used to calculate an age of 1.19 ± 0.08 Ma. In samples such as this one, the initial 234U/238U may well have been >1 and must therefore be taken into account when calculating the age. If not, ages tend to be over-estimated.

The residual 234U/238U excess was still measurable in the sample 2, and a 234U/238U ratio of 1.0077 ± 0.001 was

obtained, following the protocol outlined in Pickering et al. (2011).

Conclusions

Speleothem material from two stalagmites within the Azokh Cave Complex were considered for U-Pb dating. The first of these, sample 1, from the large stalagmite boss near the entrance of the cave proved to be unsuitable for U-Pb dating given the low U content and dominance of common Pb. Sample 2, from a small stalagmite towards the very back of the main cave, on the other hand was highly suitable for U-Pb dating, with U concentrations of close to 10 ppm, and very low Pb. This sample yielded an age of 1.19 ± 0.08 Ma which provides a minimum age for the cave itself, confirms the antiquity of the deposits, and hints at the possibility of even older occupation layers.

References

Aitken, M. J., Clark, P. A., Gaffney, C. F., & Lovborg, L. (1985). Beta and gamma gradients. Nuclear Tracks,10, 647–653.

Bischoff, J. L., Fitzpatrick, J. A., Falgueres, C., Bahain, J. J., & Bullen, T. T. (1997). Geology and preliminary dating of the hominid-bearing sedimentary fill of the Sima de los Huesos Chamber, Cueva Mayor of the Sierra de Atapuerca, Burgos, Spain.

Journal of Human Evolution,33, 129–154.

Brock, F., Higham, T., Ditchfield, P., & Bronk-Ramsey, C. (2010). Current pretreatment methods for AMS radiocarbon dating at the oxford Radiocarbon Accelerator unit (ORAU). Radiocarbon,52(1), 103–112.

Bronk Ramsey, C., Higham, T., & Leach, P. (2004a). Towards high precision AMS: Progress and limitations. Radiocarbon,46(1), 17–24.

Bronk Ramsey, C., Higham, T., Bowles, A., & Hedges R. (2004b). Improvements to the pretreatment of bone at Oxford. Radiocarbon46(1), 155–163.

Bronk Ramsey, C., Higham, T., Owen, D. C, Pike, A., & Hedges, R. (2004c). Radiocarbon Dates from the Oxford Ams System: Archaeometry Datelist 31. Archaeometry 44 (3 Supplement 1), 1– 149.

de Torres, T., García-Alonso, P., Canoira, L., & Llamas, J. F. (2000). Aspartic acid racemization and protein preservation in the dentine of European bear teeth. In M. J. C. G. A. Goodfriend, M. L. Fogel, S. A. Macko, & J. F. Wehmiller (Eds.), Perspectives in amino acids and protein geochemistry (pp. 349–355). Oxford: Oxford Univer-

sity Press.

Eggins, S., Grün, R., Pike, A., Shelley, A., & Taylor, L. (2003). 238U, 232Th profiling and U-series isotope analysis of fossil teeth by laser ablation ICPMS. Quaternary Science Reviews,22, 1373–1382.

Eggins, S. M., Grün, R., McCulloch, M., Pike, A., Chappell, J., Kinsley, L., et al. (2005). In situ U-series dating by laser-ablation multi-collector ICPMS: New prospects for Quaternary geochronology. Quaternary Science Reviews,24, 2523–2538.

Fernández, E., Ortiz, J. E., Pérez-Pérez, A., Pratts, E., Turbón, D., Torres, T., et al. (2009). Aspartic acid racemization variability in ancient human remains: Implications in the prediction of ancient DNA recovery. Journal of Archaeological Science,36, 965–972.

Fernández-Jalvo, Y., King, T., Andrews, P., Yepiskoposyan, L., Moloney, N., Murray, J., et al. (2010). The Azokh Caves complex: Middle Pleistocene to Holocene human occupation in the Caucasus.

Journal of Human Evolution,58, 103–109.

Goodfriend, G. A. (1991). Patterns of racemization and epimerisation of aminoacids in land snails shells over the course of the Holocene.

Geochimica et Cosmochimica Acta,55, 293–302.

Grandal d´Anglade, A., & Vidal Romaní, J. R. (1997). A population study on the cave bear (Ursus spelaeus Ros.Hein.) from Cova Eirós (Triacastela, Galicia, Spain). Geobios,30(5), 723–731.

Grün, R. (2000). An alternative for model for open system U-series/ESR age calculations: (closed system U-series)-ESR, CSUS-ESR. Ancient TL,18, 1–4.

Grün, R. (2002). ESR dose estimation on fossil tooth enamel by fitting the natural spectrum into the irradiated spectrum. Radiation Measurements,35, 87–93.

Grün, R. (2006). Direct dating of human fossils. Yearbook of Physical Anthropology,49, 2–48.

Grün, R. (2009a). The DATA program for the calculation of ESR age estimates on tooth enamel. Quaternary Geochronology,4, 231–232.

Grün, R. (2009b). The relevance of parametric U-uptake models in ESR age calculations. Radiation Measurements,44, 472–476.

Grün, R., & Katzenberger-Apel, O. (1994). An alpha irradiator for ESR dating. Ancient TL,12, 35–38.

Grün, R., Schwarcz, H. P., & Chadam, J. M. (1988). ESR dating of tooth enamel: Coupled correction for U-uptake and U-series disequilibrium. Nuclear Tracks and Radiation Measurements,14, 237–241.

Kaufman, D. S. (2000). Amino acid racemization in ostracodes. In G. Goodfriend, M. Collins, M. Fogel, S. Macko & J. Wehmiller (Eds.),

Perspectives in amino acid and protein geochemistry (pp. 145– 160). Oxford: Oxford University Press.

Kaufman, D. S., & Manley, W. F. (1998). A new procedure for determining DL amino acid ratios in fossils using reverse phase liquid chromatography. Quaternary Geochronology,17, 987–1000.

King, T., Compton, T., Rosas, A., Andrews, P., Yepiskoyan, L., & Asryan, L. (2016). Azokh cave hominin remains. In Y. Fernán- dez-Jalvo, T. King, L. Yepiskoposyan & P. Andrews (Eds.), Azokh Cave and the Transcaucasian Corridor (pp. 103–116). Dordrecht: Springer.

Lee-Thorp, J. (2002). Two decades of progress towards understanding fossilization processes and isotopic signals in calcified tissue minerals. Archaeometry,44, 435–446.

Lioubine, V. P. (2002). L’Acheuléen du Caucuase. Liège: Études et Recherches Archéologiques de l’Université de Liège, ERAUL 93.

Marin-Monfort, M. D., Cáceres, I., Andrews, P., Pinto, A. C., & Fernández-Jalvo, Y. (2016). Taphonomy and site formation of Azokh 1. In Y. Fernández-Jalvo, T. King, L. Yepiskoposyan & P. Andrews (Eds.), Azokh Cave and the Transcaucasian Corridor

(pp. 211–249). Dordrecht: Springer.

Marsh, R. E. (1999). Beta-gradient isochrons using electron paramagnetic resonance: Towards a new dating method in archaeology. MSc thesis, McMaster University, Hamilton.

Marzin, E. (1990). Essai de normalisation du protocole d’analyse des taux de racémisation des acides aminés: Applications a la datation d’ossements fossiles (pp. 167–178). VIII: Travaux du LAPMO.

Masters, P. M. (1986). Amino acid racemisation dating. In M. R. Zimmerman & J. L. Angel (Eds.), Dating and age

determination of biological materials (pp. 39–58). London: Croom Helm.

Masters, P. M. (1987). Preferential preservation of non-collagenous protein during bone diagenesis: Implications for chronometric and stable isotopic measurements. Geochimica et Cosmochimica Acta,51, 3209–3214.

Millard, A. R., & Hedges, R. E. M. (1996). A diffusion-adsorption model of uranium uptake by archaeological bone. Geochimica et Cosmochimica Acta,60, 2139–2152.

Murray, J., Lynch, E. P., Domínguez-Alonso, P., & Barham, M. (2016). Stratigraphy and sedimentology of Azokh caves, South Caucasus. In Y. Fernández-Jalvo, T. King, L. Yepiskoposyan & P. Andrews (Eds.), Azokh Cave and the Transcaucasian Corridor

(pp. 27–54). Dordrecht: Springer.

Murray-Wallace, C. V., & Goede, A. (1995). Aminostratigraphy and electron spin resonance dating of Quaternary coastal neotectonism in Tasmania and the Bass Strait islands. Australian Journal of Earth Sciences,42, 51–67.

Pickering, R., Dirks, P. H. G. M., Jinnah, Z., de Ruiter, D. J., Churchill, S. E., Herrires, A. I. R., et al. (2011). Australopithecus sediba at 1.977 Ma and implications for the origins of Genus Homo.

Science,333, 1421–1423.

Pike, A. W. G., Hedges, R. E. M., & Van Calsteren, P. (2002). U-series dating of bone using the diffusion-adsorption model. Geochimica et Cosmochimica Acta,66, 4273–4286.

Reimer P. J. (2009) (Guest Editor) IntCal 09 Calibration Issue. Radiocarbon 51, 1111–1187.

Richards, D. A., Bottrell, S. H., Cliff, R. A., Strohle, K., & Rowe, P. J. (1998). U-Pb dating of a speleothem of Quaternary age.

Geochimica et Cosmochimica Acta,62, 3683–3688.

Schwarcz, H. P., GriJn, R., & Tobias, P. V. (1994). ESR dating of the australopithecine site of Sterkfontein, Transvaal, South Africa.

Journal of Human Evolution,26, 175–181.

Smith, C. I., Faraldos, M., & Fernández-Jalvo Y. (2016). Bone diagenesis at Azokh cave, Nagorno-Karabakh. In Y. Fernández-- Jalvo, T. King, L. Yepiskoposyan & P. Andrews (Eds.), Azokh Cave and the Transcaucasian Corridor (pp. 251–269). Dordrecht: Springer.

Torres, T., Llamas, J. F., Canoira, L., & García-Alonso, P. (1999). Aspartic acid racemization in the dentine of bears (Ursus etruscus

G. Cuvier, Ursus prearctos Boule, Ursus deningeri von Reichenau and Ursus spelaeus Rosenmüller-Heinroth). Tooth dentine amino acids versus Mollusca amino acids. In G. Palyi, C. Zucchi & L. Caglioti (Eds.), Advances in biochirality (pp. 247–256). Amsterdam: Elsevier.

Torres, T., Ortiz, J. E., García, M. J., Llamas, F. J., Canoira, L., García de la Morena, M. A., et al. (2001). Geochemical evolution of amino acids in Pleistocene bears. Chirality,13(8), 517–521.

Torres, T., Ortiz, J. E., Llamas, F. J., Canoira, L., Juliá, R., & García-Martínez, M. J. (2002). Bear dentine aspartic acid racemization analysis, proxy for pleistocene cave infills dating. Archeometry,44(3), 417–426.

Torres, T., Ortiz, J. E., & Cobo, R. (2003). Deep cave sediments characteristics: Their influence in fossil preservation. Estudios Geológicos,59(1–4), 195–204.

Torres, T., Ortiz, J. E., Cobo, R., de Hoz, P., García-Redondo, A., & Grün, R. (2007). Hominid exploitation of the environment and cave bear populations. The case of Ursus spelaeus Rosenmüller-Heinroth in Amutxate cave (Aralar, Navarra-Spain). Journal of Human Evolution,52, 1–15.

Weiner, S. (2010). Microarchaeology: Beyond the visible archaeological record. Cambridge: Cambridge University Press.

Woodhead, J., Hellstrom, J., Maas, R., Drysdale, R., Zanchetta, G., Devine, P., et al. (2006). U-Pb geochronology of speleothems by MC-ICPMS. Quaternary Geochronology,1, 208–221.