PRECISION AND ACCURACY IN THE OPTICALLYSTIMULATED LUMINESCENCE DATING - PDF document

PRECISION AND ACCURACY IN THE OPTICALLYSTIMULATED LUMINESCENCE DATING OF SEDIMENTARYQUARTZ: A STATUS REVIEWANDREW S. MURRAY and JON M. OLLEYAarhus University, Risø National Laboratory, DK-4000 Roskilde, Denmark (e-mail: andrew.murray@risoe.dk)CSIRO Water and Land, and Co-operative Centre for Catchment Hydrology, P.O. Box 1666, Canberra, ACT 2601, AustraliaOptically stimulated luminescence (OSL) dating of light-exposed sediments is usedincreasingly as a mean of establishing a sediment deposition chronology in a wide variety oflate Quaternary studies. There has been considerable technological development in the lastfew years – in instrumentation, in the preferred mineral, and in various measurement proto-cols. New approaches to the latter, especially with the introduction of the single-aliquotregenerative-dose (SAR) protocol, have given rise to an increasing number of ages in the li-terature based on the OSL signals from quartz. This paper examines the reliability of theseindependent age control exists. It first discusses studies of modern (zero age) sediments,in water-lain sediments, i.e. sediments for which the initial light exposure is expected to haveburial dose. It then compares OSL and independent ages derived from various types of sedi-that, in general, the ages are accurate, in that there is no evidence for systematic errors overan age range from the last century to at least 350 ka. Nevertheless, the published uncertain-ties of a small fraction of OSL ages are probably underestimated. We conclude that OSLdating of quartz is a reliable chronological tool; this conclusion is reflected in its growing ey words:OSL DATING,WATER-LAINLATE PLEISTOCENE,GEOCHRONOMETRIA Vol. 21, pp 1-16, 2002 – quartz and feldspar. The release of trapped charge by lightAs a result, the time elapsed since sediment grains were(Wintle, 1997; Aitken, 1998), but over the last few years2000). At the same time, measurement protocols have PRECISION AND ACCURACY IN THE OPTICALLY STIMULATED LUMINESCENCE DATING cally 50-100, each of about 10 mg). With the developmentaliquot regenerative-dose (SAR) protocol (Murray andRoberts, 1998; Murray and Wintle, 2000), all the measure-ments for quartz required to estimate the D can now be are now based onitly (e.g. by making D measurements on single grains).all of which are based on the SAR protocol. Age estimatesbility of these SAR quartz OSL ages. The SAR protocolments. We then review both published and unpublishedin all cases some age control exists; this allows the relia-2. THE SINGLE ALIQUOT REGENERATIVE DOSEaliquot regenerative dose (SAR) protocol and its appli-cations (e.g. Murray and Olley 1999; Murray and Wintle,Table 1sets out a typical SAR measurement cycle. The sample isfirst (natural) measurement cycle. To begin the secondthe natural dose, although Murray and Wintle (2000) have against DFor the protocol to be useful, any sensitivity changes for constant D StepTreatmentObserve 1Give dose 2Preheat (160-300C for 10 s)- 3Stimulate for ~100 s at 125 4Give test dose, D 5Heat to 160 6Stimulate for ~100 s at 125 7Return to 1For the natural sample, i=0 and D is the natural dose.C after heating. In step 5, the TL signal from the testdose can be observed, but it is not made use of in routine applications.The stimulation time is dependent on the stimulation light intensity and and T are derived from the stimulation curve, typically the first 1 to 10seconds of initial OSL signal, minus a background estimated from the last partof the stimulation curve.Table 1. Generalised single-aliquot regenerative-dose protocol(after Murray and Wintle, 2000). Typical single-aliquot regenerative-dose growth curve,, see text and Table 1)interpolated onto the regenerated growth curve, for a single8 mg aliquot of a glaciofluvial sample from northern Russia(laboratory code 992528). The recycled value (R at the lowest=0 Gy, as A.S. Murray and J.M. Olley so-called recycling ratio). Preheating the sample can alsoin the absence of an ionising radiation dose). To test forthis, a SAR cycle is measured with D should then be zero, but in practiceis usually some small % of N. Rejection criteria can beproposed based on these two test measurements(e.g. 0.9   is to theseThe performance of the SAR protocol with respect to are faithfully reflected in variations. Murray and Wintle (2000; their Figure 3) did testFor feldspar, Wallinga (2001) have suggested the3. RESETTING THE OSL SIGNAL – BLEACHINGited by a high energy event (e.g. a storm or tsunami) isPredicting the rate of bleaching is complicated furtherby the nature of a transport process. Turbulent mixing andreceive the highest light fluxes. If the flux gradient is steeplight exposure to fully bleach the OSL signal. As a result diameter grains of quartz (laboratory code ME95002/2)extracted from a recent sand deposit on the Murrumbidgee River,New South Wales, Australia. Each aliquot contained between 60than 5 years old, from the east Queensland coast, Australia PRECISION AND ACCURACY IN THE OPTICALLY STIMULATED LUMINESCENCE DATING illustrates this compari-4. PREHEATING AND CHARGE TRANSFERmeasurement of any OSL signal. In the SAR protocoldescribed by Murray and Roberts (1998) and improvedby Murray and Wintle (2000), the OSL signal is measuredprocedure has been adopted widely. Additional heatingWallinga , 2000; Roberts , 1998; 1999; 2001; Wallinga C (Murray and Olley, 1999; Murray and Wintle,2000; Roberts to preheat tem-true for younger samples. Various authors have mentioned, 2001; Rhodes, 2000; Wallinga , unpublished), and Banerjee (2000) as a function of preheat temperature for an aeoliansand sample (age 310±90 years) from the coast of Wales) Filled circles: preheat plateau for quartz sample F1 of thedune section “Postdüne”, located north of Berlin infrom 160° up to 300° C (held for 10 s each; the cycle wasand standard uncertainty of 6 aliquots, except for 240°C (n=30) (0.05 Gy, open square),160 % (0.31 Gy, open circle) and 1600 % (3.1 Gy, open (unpublished). resulting from repeated heating of athe Rhine-Meuse system in the Netherlands (see Wallinga A.S. Murray and J.M. Olley TL traps at 160, 240 and 280° C. These traps can be ex- (open symbols). Here the aliquots were all firstwere then subject to the usual SAR protocol, using thevarious preheat temperatures shown. At low tempera- is very small, but at higher tem- (filled symbols) begins to rise. In both the youngWallinga with preheat – Bailey ated with continental glaciation events) such studies canusing the SAR protocol. – Olley (1998) calculated the average dosein an Australian aeolian sediment believed to be of 0.020±0.006 Gy, using a preheat of 200° C for (2001) took a sampleerosion, on the coast of north Wales, and obtained an age Murray (1995) used a simplified regen- (1998) sampled a modern in-eastern Australia, and used a 200 and dose rate values). Fur-), demonstrated that not all grainsRiver Loire in central France. They used a relatively high PRECISION AND ACCURACY IN THE OPTICALLY STIMULATED LUMINESCENCE DATING – no attempt was made to (2001)in two river basins, the Colorado (USA) and the Loire(France). In the Colorado system they collected 4 samplesfrom the Colombus Point Bar in Texas, and in the Loirefull SAR protocol, whereas that in the Loire used the sim-plified protocol of Murray (1995). In the Coloradosome averaging was probably unavoidable. In the Loire3.3 ka near the source, to about 80 years at the mouth; open circles). If some allowance was made for – In a study of a possible tsunami deposit onet al. (2001) sampled mo-below the sediment surface and more than 2 m below6. HOLOCENE AND LATE PLEISTOCENE SEDIMENTS – Strickertsson and Murray (1999) sampled (2001) dated a small dune field on for bedload samples collected within thechannel of the Loire River in France (after Stokes Schematic cross-sections of (a) the interdune area and modern parabolic dune and (b) aeolian sand stratigraphy at LakeCoron, on the coast of Wales, UK, derived from ground penetrating radar images. The OSL ages (ka) and sample locations are alsoshown (modified by Bailey [pers. comm.] from Bailey A.S. Murray and J.M. Olley the west coast of north Wales (This is consistent with the historical evidence that this were independent of preheatRadtke (2001) undertook a comparison of quartzsands immediately above and below the Laacher-See te-many. Using the SAR protocol, and a preheat of 260° C Diagrammatic section of theLodbjerg site in western Jutland, DenmarkC dates. S3 is a complexshown, with uncertainties of half the range;convert to calendar years. PRECISION AND ACCURACY IN THE OPTICALLY STIMULATED LUMINESCENCE DATING tent with the well-known age for the Laacher-See tephrasamples of poplar buried by the tephra (Friedrich (2001) undertook a related study nearthat contains both the Laacher-See tephra and a well-Allerød interstadial (12.9-14 ka). Their study also includedthe sample immediately overlying the Laacher-See tephra,Mexico and Texas, USA). The sites were of archaeologi-which a comparison with SAR data can be drawn, themean ratio of SAR to independent age is 1.12±0.17. (2000) report two comparisons ofern Russia. One is at the Pymva Shor archaeological site,12.0±0.9 and 13.6±1.2 ka. The other is at their Kuyasediment sample); after calibration this gives 14.3±0.5 ka.Freshwater sediments – Olley (1998) measured the700 years (preheat 200° C for 10 s), but by using small (1999) later examined the dose distribu-origin through the data point until the line intersects the Radial plots of measured doses for single grains from (a) sample ME95041B and (b) sample WK96008. In each plot,the shaded region represents the expected burial dose (after Olley A.S. Murray and J.M. Olley (1999)from south-eastern Australia. In each case the samplesexample, from the Bega estuary in New South Wales, thefrom Blue Lake, one of the highest lakes in Australia,rate of sediment supply is assumed. Olley and TaylorLake Complex, Wimmera, Australia. The first appearancequartz each consisting of ~10 grains (preheat of 220°CWallinga (2001) have dated a sequence of aban-doned river channels from the Rhine-Meuse system in the summarises the comparison derived from small aliquots) with the indepen-sponding OSL age is 920±100 years, and the differenceC ages from Late-Glacial lacus-Table 2, lines 4 and 5). TheLarsen (1999) report one comparison at theirChelmokhta site from northern Russia, where five freshwater Bølling-Allerød (14.1-14.5 ka) and YoungerDryas (11.1-12.9) sediments, from Nørre Lyngby on theMurray, 1999). They used preheats of between 240 and280° C for 10 s, and obtained SAR ages of 13.6±1.1 ka(Bølling-Allerød) and 9.8±0.7 and 8.2±0.6 (Younger LocalitySample [ka] [ka]Organic materialOSL/Lønstrup97020330±233±2plant0.91±0.08 97020429±232±3moss0.91±0.11Lodbjerg98020330±333±1plant0.91±0.10 98020113.6±1.013.9±0.5plant0.98±0.08 Bovbjerg99020513.8±0.914.0±0.5plant0.99±0.06Møn, Kobbel Gård99021926±232±2gyttja0.81±0.0899022029±230±2seed0.97±0.09 00023028±227±1.0teeth1.04±0.08 Table 2. Summary of comparisons between OSL and calibrated OSL ages plotted against independent age estimates forNetherlands (after Wallinga PRECISION AND ACCURACY IN THE OPTICALLY STIMULATED LUMINESCENCE DATING underestimate the independently known age. We do notconsider their Podzol Bh-horizon sample, because theauthors state that this soil was formed on Younger Dryas – Stokes (2001) have reported a set of 5 on preheat temperature, in the range200 to 280° C, and preheat temperatures of 200 and includesLyngby section. These were from the Older and YoungerYoldia Clay, with independent ages based on calibratedshell of about 24 ka, and 17.2±0.4 ka.Their SAR OSL ages were independent of preheat tem-OSL age (25.3±1.8 ka) from the Older Yoldia Clay wastion of the expected ages for the Younger Yoldia Clay,(2001) report further ages on the Younger Yoldia clay,misidentified in the field (the Older Yoldia Clay [24 ka]is very similar to the Younger). The sand layer above thesupposed Younger Yoldia Clay was believed to be Upper – Watanuki (submitted) have examinedited on two river terrace sites (Niigata and Tochigi) in kawestern Australia, Turney (2001) report a compari- (2001) report a compari-±±ka). Although the older ages obtained using conventionalpretreatments showed clear evidence of the ‘radiocarbonbarrier’ (Roberts bustion (ABOX-SC) provided ages beyond 40 ka. Two ofC ka BP, can be directlyTurney (2001) suggest that these Chronological models for core 70KL, taken from Stokes (submitted). OSL dates are based on silt-sized quartzare calibrated. Other age control includes the Toba Ash (variablyby Ar-Ar), a key biostratigraphic marker horizon, LAD G. rubercomparison of the oxygen isotope record with the SPECMAP-coefficient=0.94). Details of these independent age controls (submitted). A.S. Murray and J.M. Olley and van der Plicht (1998) and Voelker (1998).Freshwater – Tanaka (2001) have worked withing preheating for 10 s at 240° C. At one site age controlYamagata site), and their SAR age of 55.6±1.3 ka, calcu-Roberts (2001) reported anAustralia, which were bracketed by flowstones with(below). They also reported U ages from twoLarsen (1999) present one comparisonfrom their Trepuzovo site, where an (uncalibrated) twigs) gave 42.6±1.5 ka BP, compared (2001) have reported a set of 3 older OSL shows that these older ages areComparison of OSL ages from silt-sized quartz grainswith an independent tephra chronology (Watanuki submitted). The tephra ages are based on contributed to the low dose rates of about 1 Gy (unpublished) have obtained two dateset al.(2000) discuss two sites in northern Russia with deposits (2000)layers to clayey silt at the bottom. Late Saalian freshwa-parent trend in the SAR OSL ages with depth, and all 24derived uncertainties are slightly underestimated. This Fig. 11. Distribution of dates (obtained using a preheat of260C for 10 s) from 24 samples of Eemian coastal marinesand taken from a coastal cliff section near Gammelmark, southeast Jutland. There was no systematic change in age with depthi.e. excluding the lowest two ages). PRECISION AND ACCURACY IN THE OPTICALLY STIMULATED LUMINESCENCE DATING Summary of age comparisons from all sites discussedin this paper. Note the logarithmic horizontal axis. The OSL toindependent age ratios are shown in the top part of the figure, (1999) –pretreatment and is uncalibrated. Two other pairs, from Wallingaet al. (2001; see Figure 8), are omitted from the upper part ofthe diagram only, because the independent age (1.54±0.84 ka)sample by Mangerud (2000) reported above; this – As part of his study ofhas obtained several SAR quartz OSL ages with good Table 2ment between OSL and the independent chronology is8. DISCUSSIONFig. 12 and Table 3 comparisons discussed above. In order not to bias the dataTable 3The older uncalibrated C ages of Turney (2001)Plicht, 1998, and Voelker estimate from sediment of known finite age (WallingaTurning now to one study (Watanuki A.S. Murray and J.M. Olley minescence ages. Combined uncertainties range from50% (Olley and Taylor, unpublished) to 2.3% (Stokesa discussion of the analysis of random and systematicClassAliquot and grain sizePreheat, 10 s oC] OSL Age [ka]Age [ka]Reference l , 0.29±0.020.35±0.03Strickertsson and Murray, l , 0.71±0.05Bailey et al., 2001 & pers. c l , 13.00±0.7Radtke et al. l , 11.2±1.3Hilgers et al. l , 13.1±0.913.45±0.3Hilgers et al. l , 12.6±0.712.0±0.3*Mangerud et al. l , 14.6±1.214.3±0.5*Mangerud et al. l , 4.23±0.14.31±0.07Murray and Clemmensen, l , 2.7±0.32.81±0.02Murray and Clemmensen, l , 2.0±0.22.00±0.05Murray and Clemmensen, l , 0.92±0.040.87±0.04Murray and Clemmensen, l , 93±1098±9Watanuki et al. s , 25.5±1.428±2*Turney et al. s , 44.1±2.143±2*Turney et al. s , 47.1±2.648±2*Turney et al. l , 215±22170±20Watanuki et al. l , 311±33290±60Watanuki et al. l , 296±39290±30Watanuki et al. l , 308±36290±70Watanuki et al. l , 53±351±1Watanuki et al. Aeolian , 145±12135±15Watanuki et al. s , 67±5 aOlley et al. l , 13.6±1.11 14.3±0.1Strickertsson and Murray, l , 9.0±0.612±0.3Strickertsson and Murray, s , 0.92±0.10Wallinga et al. s , 1.49±0.101.54±0.84Wallinga et al. s , 5.62±0.355.62±0.41Wallinga et al. s , 13.26±0.813.24±0.07Wallinga et al. s g 70±8 a63±8 aOlley and Hancock (unpub.) s g 170±20 a128±10 aOlley and Hancock (unpub.) s , 29±15 aOlley and Taylor (unpub.) l , 13.6±1.013.9±0.5Houmark-Nielsen (Table 2) l , 13.8±0.914±0.5Houmark-Nielsen (Table 2) l , 13.7±1.111.1±0.3Larsen et al. l , 55.6±1.358±2Tanaka et al. Fluvial , 55±949.8±4Roberts et al. l , 25.3±1.824±2Strickertsson and Murray, l , 14.9±0.617.2±0.4Strickertsson and Murray, l , 17.3±1.516.2±0.7Strickertsson and Murray, l , 119±7122±7Murray et al. (unpub.) l , 135±8122±7Sigaard et al. (unpub.) l , 101±4122±7Mangerud et al. l , , 7.31±0.187.50±0.09Stokes et al. l , , 22.1±0.420.0±0.12Stokes et al. l , , 36.3±0.843±2Stokes et al. l , , 67±271±4Stokes et al. Marine , , 117±3128±6Stokes et al. l , 30±233±2Houmark-Nielsen (Table 2) l , 29±232±3Houmark-Nielsen (Table 2) l , 30±333±1Houmark-Nielsen (Table 2) l , 26±232±2Houmark-Nielsen (Table 2) l , 29±230±2Houmark-Nielsen (Table 2) Glacial , 28±227±1Houmark-Nielsen (Table 2) 1. Aliquot size: l - large, s - small, sg - single grain. Grain size, c - coarse, f - silt. 2. (n) is the number of OSL ages included in the average given. 3. * indicates radiocarbon age calibrated by the present authors. Table 3. Summary of all age comparisons used in Figure 12. PRECISION AND ACCURACY IN THE OPTICALLY STIMULATED LUMINESCENCE DATING include contributions from all known components, includ-random errors, especially errors associated with measure- of are possible using SAR, it is very important that full are simplyavailable between quartz SAR ages and independent agenately this is very rare. With the increased precision ava-ilable from the SAR protocol, such detailed error analy-certainties is to be avoided. We stress that determinationStokes. Andrzej Bluszcz drew our attention to the NISTGuidelines (Taylor and Kuyatt, 1994) and made severalwas consistent with recommended practice. Ann Wintleand Jakob Wallinga also offered valuable criticism of theAitken M.J., 1976: Thermoluminescent age evaluation and asses- 18: 233-238.Aitken M.J., 1985Aitken M.J., 1998: An Introduction to Optical Dating. Aitken M.J and Alldred J.C., 1972 14: 257-267.Bailey S.D., Wintle A.G., Duller G.A.T. and Bristow C.SNorth Wales as determined by OSL dating of quartz. nary Science Reviews (Quaternary Geochronology) 20: 701-704.Banerjee D., 2000In: Murthy K. V. R. eds, Banerjee D., Murray A.S. and Foster I.D.L, 2001Quaternary Science Reviews (Quaternary Geo- 20: 715-718.Bøtter-Jensen L., Bulur E., Duller G.A.T. and Murray A.S., 2000Advances in luminescence instrument systems. 32: 523-528.Bøtter-Jensen L. and Duller G.A.T., 1992Nuclear Tracks and Ra- 20: 549-533.Colls A.E., Stokes S., Blum M.D. And Straffin E., 2001on the Late Quaternary evolution of the upper Loire River.Quaternary Science Reviews 20: 743-750.Friedrich M., Kromer B., Spurk M., Hofmann J. and Kaiser K.L.,: Paleo-environment and radiocarbon calibration as deri-ved from Lateglacial/Early Holocene tree-ring chronologies. 61: 27-39. A.S. Murray and J.M. Olley Galbraith R., Roberts R.G., Laslett G., Yoshida H. and Olley J, 1999Optical dating of single and multiple grains of quartz from Jin-mium rock shelter, Northern Australia. Part I: Experimental 41: 339-364.Hilgers A., Murray A.S., Schlaak N. and Radtke U., 2001rison of quartz OSL protocols using Lateglacial and Holocenedune sands from Brandenburg, Germany. Reviews (Quaternary Geochronology) 20: 731-736.Kitigawa H. and van der Plicht J., 1998: Atmospheric radiocarboncalibration to 45,000 yr B.P.: Late Glacial fluctuations and 279: 1187-1190.Larsen E., Lyså A., Demidov I., Funder S., Houmark-Nielsen M.,Kjær K.H. and Murray A.S., 1999dinavian ice sheet in northwest Russia. 28: 115-132.Mangerud J., Svendsen J.I. And Astakhov V.I., 2000of the Barents and Kara ice sheets in Northern Russia. Murray A.S. and Clemmensen L.B., 2001Science Reviews (Quaternary Geochronology) 20: 751-754.Murray A.S. and Olley J.M., 1999tes using luminescence dating. In: Bruns P. and Hass H.C., eds., GeoResearchForum, Trans Tech Publications, Switzerland: 121-144.Murray A.S., Olley J.M. and Caitcheon G.C., 1995sediments using optically stimulated luminescence. ry Science Reviews (Quaternary Geochronology) 14: 365-371.Murray A.S. and Roberts R.G., 1998: Measurement of the equiva- 29: 503-515.Murray A.S., Roberts R.G. and Wintle A.G., 1997: Equivalent dose 27: 171-184.Murray A.S. and Wintle A.G., 2000 32: 57-73.Murray A.S., Wintle A.G. and Wallinga J., 2002Oliver R.L., 1990ling Basin, southeastern Australia. Australian Journal of Mari-ne and Freshwater Research 41: 581-601.Olley J.M., Caitcheon G.C. and Murray A.S., 1998Quaternary Science Reviews (Qu- 17: 1033-1040.Olley J.M., Caitcheon G., and Roberts R.G., 1999 30: 207-217Radtke U., Janotta A., Hilgers A. and Murray A.S., 2001potential for OSL dating Lateglacial and Holocene dune sandswith independent age control of the Laacher See tephra (12880Reviews (Quaternary Geochronology) 20: 719-724.Rhodes E.J., 1988Quaternary Science Reviews (Quaternary Geo- 16: 275-280.Rhodes E.J., 2000 32: 595-602.Rich J. and Stokes S., 2001Texas, USA. Quaternary Science Reviews (Quaternary Geochro- 20: 949-960.Roberts R., Bird M., Olley J, Galbraith R., Lawson E., Laslett G.,Yoshida H., Jones R., Fullagar R., Jacobsen G and Hua Q., 1998northern Australia. 393: 358-362.Roberts R.G., Flannery T.F., Ayliffe L.K., Yoshida H., Olley J.M.,Prideaux G.J., Laslett G.M., Baynes A., Smith M.A., Jones R.,: New ages for the last Australian megafau-Roberts R.G., Galbraith R., Olley J, Yoshida H., and Laslett G.,Jinmium Rock Shelter, Northern Australia. Part II: results and 41: 365-395.Roberts R.G., Jones R and Smith M.A., 1994carbon barrier in Australian prehistory. 68: 611-616.Schlaak N., 1993: Studie zur Lanschaftsgenese im Raum Nordbar- 76: 146 p.Stokes S., Bray H.E. and Blum M.D., 2001: Optical resetting in lar-Quaternary Science Reviews (Quaternary 20: 880-885.Stokes S., Ingram S., Aitken M.J., Sirocko F. and Anderson, R.,: Alternative chronologies for Late Quaternary (last inter-Quaternary Science Reviews (Quaternary Geo-Strickertsson K. and Murray A.S., 1999minescence dates for Late Pleistocene and Holocene sedimentsfrom Nørre Lyngby, Northern Jutland, Denmark. Science Reviews (Quaternary Geochronology) 18: 169-178.Strickertsson K., Murray A.S and Lykke-Anderson H., 2000cally stimulated luminescence dates for Late Pleistocene sedi-Science Reviews (Quaternary Geochronology) 20: 755-759.Tanaka K., Hataya R., Spooner N.A. and Questiaux D.G., 2001Optical dating of river terrace sediments from Kanto plains,Quaternary Science Reviews (Quaternary Geochronolo- 20: 826-828.Taylor B.N. and Kuyatt C.E., 1994tional Institute of Standards and Technology, NIST Technical Note1297, US Government Printing Service: 24 pp.Turney C.S.M., Bird M.J., Fifield L.K., Roberts R.G., Smith M.,Dortch C.E., Grün R., Lawson E., Ayliffe L.K., Miller G.H.,Dortch J. and Creswell R.G., 2001Devil’s Lair, southwestern Australia 50,000 years ago. nary Research 55: 3-13.Voelker A.H.L., Sarntheim M., Grootes P.M., Erlenkeuser H., LajC., Mazaud A., Nadeau M.-J. and Schleicher M., 1998ka BP, 40: 517-534.Wallinga J., Murray A.S., Duller G.A.T. and Törnqvist T.E., 2001Testing optically stimulated luminescence dating of sand-sized Earth and Planetary193: 617-630.Watanuki T., Murray A.S. and Tsukamoto S., 2002 submittedWintle A.G., 1997 27: 769-817. PRECISION AND ACCURACY IN THE OPTICALLY STIMULATED LUMINESCENCE DATING