A review of current research on TL dating of loess

The thick loess deposits of China, Central Europe and North America are particularly suitable for the application of the thermoluminescence (TL) dating method because individual grains are likely to have travelled large distances and thus been well exposed to light before deposition. Wind-blown silt grains collected close to glacial rivers in Alaska have been shown to give a ‘zero age’ of not more than 2 ka, demonstrating the efficiency of the zeroing mechanism.Differences in laboratory procedures can cause differences in the TL ages reported, particularly for loess over 100 ka. TL ages for interstadial soils in Europe are in agreement with the very few radiocarbon dates on reliable material, such as charcoal. On the other hand TL dates from sites in Belgium and north-western Germany indicate that the previously accepted chronology, which was based on two radiocarbon dates on humic-rich sediments, is incorrect.The use of the ‘last interglacial’ palaeosol for assessing the TL dates on loess above and below it is limited by the uncertainty in the timing of termination of soil-forming processes; 107 and 71 ka are the limits suggested by the astronomically-derived time scale. Results on deposits from China, North America, Alaska and Europe are discussed in this context.     

Relic permafrost structures in the Gobi of Mongolia: age and significance

Relict permafrost structures (ice-wedge casts and cryoturbation structures) are present in the Gobi of southern Mongolia. Luminescence dates of sediments are presented to constrain the age of formation of permafrost structures. These data show that there was a phase of permafrost development during the latter part of the Last Glacial (after about 22 to 15 ka) that resulted in cryoturbated sediments and ice-wedge casts. Furthermore, permafrost degradation occurred during late Pleistocene times (13–10 ka) and was absent during the early Holocene. These permafrost structures mark the southernmost evidence of permafrost in northern Asia during late Quaternary times and indicate that the mean annual air temperature was below approximately −6°C during their formation. © 1998 John Wiley & Sons, Ltd.     

Inland aeolian deposits of south‐west France: facies,stratigraphy and chronology

Archaeological investigations undertaken along a proposed highway together with the compilation of available geological and pedological data made it possible to give a first overview of the distribution of Pleistocene aeolian deposits in south‐west France. A chronological framework for deposition has been obtained using both radiocarbon (n = 24) and luminescence (n = 26) dating. It shows that aeolian transport was very active during the Late Pleniglacial, between 15 and ～23 ka, leading to sand emplacement over a 13 000‐m² area at the centre of the basin. The Pleniglacial coversands are typified by extensive fields of small transverse to barchanoid ridges giving way to sandsheets to the east. Subsequent aeolian phases, at ca. 12 ka (Younger Dryas) and 0.8–0.2 ka (Little Ice Age), correspond to the formation of more localized and higher, mainly parabolic dunes. At the southern and eastern margins of the coversand area, aeolian dust accumulated to form loess deposits, the thickness of which reaches ～3 m on the plateaus. Luminescence dates together with interglacial‐ranking palaeoluvisols between the loess units clearly indicate that these accumulations built up during the last two glacial–interglacial cycles. The chronology of sand and loess deposition thus appears to be consistent with that already documented for northern Europe. This suggests that it was driven by global climate changes in the northern hemisphere. The relatively thin aeolian deposits (and particularly loess) in south‐west France is thought to reflect both a supply‐limited system and a moister climate than in more northern and continental regions. Copyright © 2011 John Wiley & Sons, Ltd.     

Early Holocene climate change and human occupation along the semiarid coast of north‐central Chile

The brief, terminal Pleistocene archaeological site at Santa Julia (SJ, 31° 50′ S; 71° 45′ W) is the only one with fluted projectile preforms and megafauna consumption known from the Chilean semiarid coastline. Here, we present the climatic history at SJ during the early Holocene reconstructed from pollen and charcoal analyses spanning 13.2–8.6 ka (=10³ calibrated ¹⁴C yr BP). Elevated charcoal concentrations confirm human activity by 13.2 ka. Human occupation decreased in intensity and charcoal practically disappears from the record after 10.6 ka, followed by wetland expansion at SJ between 10.5 and 9.5 ka. Local dominance of coastal shrubland reveals that dry phases occurred between >11.2–10.5 and 9.5–9.0 ka. Overall, these findings imply that by modulating available resources at both local and landscape levels climate change may have played an important role in explaining the peopling of semiarid coastal Chile. Copyright © 2010 John Wiley & Sons, Ltd.     

Phytoliths as quantitative indicators for the reconstruction of past environmental conditions in China II: palaeoenvironmental reconstruction in the Loess Plateau

Quantitative reconstruction of the climatic history of the Chinese Loess Plateau is important for understanding present and past environment and climate changes in the Northern Hemisphere. Here, we reconstructed mean annual temperature (MAT) and mean annual precipitation (MAP) trends during the last 136 ka based on the analysis of phytoliths from the Weinan loess section (34°24′N, 109°30′E) near the southern part of the Loess Plateau in northern China. The reconstructions have been carried out using a Chinese phytolith–climate calibration model based on weighted averaging partial least-squares regression. A series of cold and dry events, as indicated by the reconstructed MAT and MAP, are documented in the loess during the last glacial periods, which can be temporally correlated with the North Atlantic Heinrich events. Our MAT and MAP estimations show that the coldest and/or driest period occurred at the upper part of L2 unit (Late MIS 6), where MAT dropped to ca 4.4 °C and MAP to ca 100 mm. Two other prominent cold-dry periods occurred at lower Ll-5 (ca 77–62 ka) and L1-1 (ca 23–10.5 ka) where the MAT and MAP decreased to about 6.1–6.5 °C and 150–370 mm, respectively, ca 6.6–6.2 °C and 400–200 mm lower than today. However, the highest MAT (average 14.6 °C, max. 18.1 °C) and MAP (average 757 mm, max. 1000 mm) occurred at Sl interval (MIS 5). During the interstadial of L1-4–L1-2 (MIS 3) and during the Holocene warm-wet period, the MAT was about 1–2 °C and MAP 100–150 mm higher than today in the Weinan region. The well-dated MAT and MAP reconstructions from the Chinese Loess Plateau presented in this paper are the first quantitatively reconstructed proxy record of climatic changes at the glacial–interglacial timescale that is based on phytolith data. This study also reveals a causal link between climatic instability in the Atlantic Ocean and climate variability in the Chinese Loess Plateau.     

The last 750 ka in loess–palaeosol sequences from northern France: environmental background and dating of the western European Palaeolithic

This study presents an overview of Middle Pleistocene loess–palaeosol sequences (LPS) in northern France and discusses the palaeoclimatic significance of the pedosedimentary record in the context of western European LPS and of global climatic cycles for the last 750 ka. In this area, the oldest loess deposits (early Middle Pleistocene) are preserved in sedimentary traps (leeward scarps of fluvial terraces and dissolution sinkholes). They result from local deflation processes reworking Pleistocene sandy fluvial deposits or relicts of Tertiary sands. A large extension of typical calcareous loess over the landscape, the Loess Revolution, is then observed during MIS 6, with heavy mineral assemblages testifying to long-distance transport from the polar desert area of the dried eastern Channel. A correlation scheme is proposed between the global records of northern France in continental environments and both global palaeoclimatic records and other main western European LPS. After 30 years of research, northern France LPS stand as a fundamental archive of the impact of interglacial–glacial climatic cycles as well as millennial events. Finally, these works provide a robust chronoclimatic framework for the study of the western European Late Acheulean and Middle Palaeolithic and for the relative dating of the various fluvial terraces that they fossilise.     

Thermoluminescence dating of St. Croix ceramics: Chronology building in Southwestern Nova Scotia

Using the classic thermoluminescence (TL) dating technique for fired ceramic materials, we have obtained the first direct ages for five ceramic artifacts recovered from BfDa-1, a prehistoric archaeological site located in St. Croix, southcentral Nova Scotia. BfDa-1 is the only archaeological site in Nova Scotia to produce the full range of ceramic styles associated with the Woodland or Ceramic Period (c. 1050 B.C. to A.D. 1500); thus our new chronology can be used to revise the current local and regional ceramic chronologies. The five sherds from the St. Croix site yielded absolute gas of 1.15 ± 0.15 ka to 2.62 ± 0.29 ka (1 ka = 1000 years). The oldest of these TL ages was obtained on a sherd decorated with a pseudoscallop shell design and is in excellent agreement with a ¹⁴C date of 2500 ± 120 B.P. associated with Early Ceramic artifacts at this site. The other TL ages are in agreement with the relative ceramic chronology deduced from their decorative attributes. All five TL dates are in the correct depth-age order. This demonstrates that the recent excavations explored a part of the site which remained undisturbed in spite of extensive agricultural and horticultural activities in the vicinity in recent centuries. The dates also indicate a high degree of compression for the cultural remains at the site. They suggest a sediment deposition rate of 1.3 cm/100 yr during the early stages of the occupation period (2000–2600 yr B.P.), and a decrease in the deposition rate to 0.5 cm/100 yr during the last 2000 years. These dates provide the first successful application of TL dating to ceramics of the Minas Basin area. They confirm an initial hypothesis based on the stylistic attributes of ceramics recovered from BfDa-1, that human occupation at the site must have been of long duration. The excellent quality of the analytical data indicates that the TL dating technique should be well suited to the study of ceramic technology in other parts of the province, and that local mineralogy is suitable for optical dating of sediments at the site and elsewhere in Nova Scotia. © 1997 John Wiley & Sons, Inc.     

天津大直沽晚第四纪沉积物红外释光测年及环境变迁年代学

对天津大直沽ZH2钻孔晚第四纪沉积物岩芯12个样品的红外释光(IRSL)测年及沉积物记录的环境变化研究结果表明:1)细颗粒(4～11μm)多测片的红外释光(IRSL)技术对水悬浮沉积物的年龄测定有着巨大的潜力,渤海湾西岸全新世环境变化的IRSL年代可与¹⁴C年代相对比;2)大直沽ZH2孔所在地未见晚更新世海侵,并在距今约30 ka至约10 ka期间处于沉积间断状态,距今9.5 ka开始发生海侵,距今5.1 ka发生海退,距今4.4 ka海水已退出ZH2孔所在地,距今2 ka左右已有人类活动.     

Luminescence chronology of the Upper Pleistocene loess record at Kurtak in M iddle Siberia

The loess/palaeosol sequence of Kurtak, situated at the western bank of the upper Yenisei in Middle Siberia, represents one of the best developed Middle and Upper Pleistocene sediment records in Yenisei Siberia. More than 40 m thick loess and loess-like sediments intercalated by at least four pedocomplexes are exposed at a steep erosional slope at the bank of the Krasnoyarsk Water Reservoir. Infrared optically stimulated luminescence (IRSL) and thermoluminescence (TL) dating techniques have been applied on 38 fine grain samples from the upper 23 m of the profile, representing the penultimate and last interglacial–glacial cycle. The IRSL and TL age estimates are in good agreement with the geological estimates up to the last interglacial soil horizon (oxygen isotope substage (OIS) 5e). The luminescence ages show that the lowermost truncated palaeosol of kastanosjem-type is likely to have formed during the penultimate interglacial upon subaerial deposits. Three weak reddish brown palaeosols intercalated by reworked loess-like sediments correlate with early Upper Pleistocene interstadials (OIS5dion of -a), and a succession of humic horizons alternated by cryoturbation processes (Kurtak pedocomplex) is linked with OIS 3. Thick loess deposits between the pedocomplexes show now significant age increase with depth, indicating high accumulation rates at around 23 ka (OIS 2) and 60 ka (OIS 4).     

Last glacial maximum ecology and climate from terrestrial gastropod assemblages in Peoria loess,western Kentucky

The Rocks loess section, in unglaciated western Kentucky, provides a high-resolution environmental record during the last glacial maximum onset. The Peoria Silt (9 m thick) contains 26 terrestrial gastropod species, with up to 15 species within a single 5 cm interval. Thirteen radiocarbon ages, using shells or charcoal, range between 30 and 24.5 cal ka; younger loess has been leached or eroded. Stratigraphic shifts in gastropod assemblages imply significant cooling, particularly ~27 cal ka, as solar insolation was decreasing and the southern Laurentide Ice Sheet rapidly advancing. Midwestern to southern species (e.g. Anguispira kochi, Gastrocopta pentodon, Hawaii miniscula, Helicodiscus parallelus, Vallonia perspectiva) occur only in the lowermost Peoria Silt (~30–27 cal ka). In contrast, cold-tolerant species (Columella alticola, Vertigo modesta, Vallonia gracilicosta) occur only in full glacial Peoria Silt (27–24.5 cal ka). Inferred mean July temperatures, from mutual climatic range methods, range from ~23 °C at 30 cal ka, cooling to ~18 °C by 26 cal ka; about 3–8 °C cooler than today (~26 °C). Superimposed on this cooling trend are multi-centennial variations in detrital carbonate, fossil shell concentrations, palaeotemperature estimates, and oxygen isotope values (Vertigo, Discus, Helicodiscus). The finer-scale variations imply relatively synchronous fluctuations in glacial sediment supply, loess sedimentation, and climate.     

郑州邙山马兰黄土的光释光(OSL)测年初步研究

对郑州市西北邙山黄土塬赵下峪(34°58'N,113°22'E)剖面上部马兰黄土(厚约87m)不同层位的24个样品作了细颗粒(4-11μm)组分红外释光(IRSL)测年,其中8个样品同时进行了细颗粒组分绿光释光(GLSL)测年。样品的IRSL和GLSL信号强度都在Daybreak1100TL/OSL检测系统中测量。该系统的本底计数为70-80光子/秒。被检测的IRSL和GLSL波长分别为340-480nm和340±25nm;激发光束波长分别为880±80nm和514±14nm,功率为18mW和15-16mW。所有样品的等效剂量都用再生释光法测定;环境剂量率是通过测定样品的铀、钍和钾含量,按Aitken(1985)的转换系数确定的,考虑了含水量的影响及宇宙射线的贡献。从这批样品的光释光测年结果可得以下初步认识:
(1)8个样品细颗粒组分的IRSL和GLSL测定的等效剂量和年龄值,除1个样品外,都在1-2σ范围内一致。这可能提供了沉积物光释光测年可靠性的一种自检方法。(2)邙山剖面马兰黄土不同层位段的沉积速率变化十分显著,从0.4m/ka到5.6m/ka,并与剖面上质量磁化率测定值的变化大致相吻合。该剖面马兰黄土至少有4个快速堆积层(沉积速率>3m/ka),其磁化率低而变化小;3个缓慢堆积层(沉积速率<0.5m/ka),其磁化率大或变化显著,它们之间有一系列过渡层。(3)邙山马兰黄土大体可三分即上部(L_1-1)埋深2.7-27.5m,中部(L_1-2)埋深27.5-57.9m)和下部(L_1-3)埋深57.9-87.9m。它们的形成年代分别为10.8-36.2ka B P,36.2-70.3ka B P和70.3-80.2ka B P。较详细的黄土-古土壤序列年代表将在文中讨论      

Early Holocene loessic colluviation in northwest England: new evidence for the 8.2 ka event in the terrestrial record?

Vincent, P. J., Lord, T. C., Telfer, M. W. & Wilson, P. 2010: Early Holocene loessic colluviation in northwest England: new evidence for the 8.2 ka event in the terrestrial record? Boreas, 10.1111/j.1502‐3885.2010.00172.x. ISSN 0300‐9483. Twelve new samples of loessic silts from widely spaced locations on the karst uplands of northwest England have yielded Optically Stimulated Luminescence (OSL) dates that fall within or overlap with (within uncertainties) the early to mid‐Holocene period (11.7–6.0 ka), and support three already‐published Holocene ages from similar sediment from this region. Nine of the 15 dates are coincident with the hypothesized climatic deterioration at 8.5–8.0 ka in the North Atlantic region and eight are coincident with the 8.2 ka event. These dates demonstrate that the silts are not primary air‐fall loesses of deglacial/Lateglacial age (c. 18.0–11.7 ka) but have been reworked and now consist of loess‐derived colluvial deposits; we consider the ages to be reliable as there is no compelling evidence to indicate that the samples are partially bleached. There is no substantive archaeological or palynological evidence for Late Mesolithic hunter‐gatherers having had a major impact on the landscape, and it is considered highly unlikely that these people triggered colluviation. We estimate that during the 8.2 ka event there was a reduction in mean annual air temperature at these upland locations of ～2.6–4.6 °C, and proxy evidence from other sites indicates a shift to wetter conditions. It is inferred that there was greater snow accumulation in winter, that the snowpack survived for longer periods, and that there was an increase in the magnitude and frequency of frost‐related processes and meltwater flooding. Together, these changes in climate and their associated (sub)surface processes were responsible for the reworking of the loess. The OSL dates indicate climatically induced landscape dynamism in Great Britain during the latter half of the ninth millennium.     

Spatial distribution of mean winter air temperatures in Siberian permafrost at 20−18 ka BP using oxygen isotope data

Palaeotemperature reconstruction for the period of 20?18 ka BP in Siberia is here based on δ¹⁸O analysis and ¹⁴C dating of large syngenetic ice wedges. Dozens of yedoma exposures, from Yamal Peninsula to Chukotka, have been studied. Snow meltwater is considered to be the main source of ice‐wedge ice. The modern relationship between δ¹⁸O composition of ice‐wedge ice and winter temperature is used as a base for reconstruction. In modern ice wedges (elementary veins that have accumulated during the last 60–100 years) δ¹⁸O fluctuates between ?14 and ?20‰ in western Siberia and between ?23 and ?28‰ in northern Yakutia. The trend in δ¹⁸O distribution in ice wedges dated at 20?18 ka BP is similar to the modern one. For example, the δ¹⁸O values in Late Pleistocene wedges are more negative going from west to east by 8–10‰, i.e. from ?19 to ?25‰ in western Siberian ice wedges to ?30 to ?35‰ in northern Yakutia. However, values are as high as ?28 to ?33‰ in north Chukotka and the central areas of the Magadan Region and even as high as ?23 to ?29‰ in the east of Chukotka. The same difference between the oxygen isotope composition of ice wedges in the eastern and western regions of Siberian permafrost (about 8–10‰) is also preserved from 20?18 ka BP to the present: δ¹⁸O values obtained from large ice wedges from the Late Pleistocene vary from ?19 to ?25‰ in western Siberia to ?30 to ?35‰ in northern Yakutia. We conclude that, at 20?18 ka BP, mean January temperatures were about 8–12°C lower (in Chukotka up to 17–18°C) than at present.     

Timing of Late Quaternary glaciations in the Himalayas of northern Pakistan

Optically stimulated luminescence dating of Late Quaternary glaciogenic sediments was undertaken in critical areas of the Himalayas of northern Pakistan in order to examine the timing of glaciation. The dates demonstrate that several glaciations occurred during the last glacial cycle. In Swat, the Grabral 2 Stade and the Kalam I Stade were dated at ca. 77 ka and ca. 38 ka, respectively. The error on the former date is large and it is conceivable that the moraines may have formed during the early part of Oxygen Isotope Stage 3 rather than during Oxygen Isotope Stage 4. The Kalam I Stade, however, clearly represents a glaciation during Oxygen Isotope Stage 3. The oldest moraines and those at the lowest altitude in the Indus valley at Shatial have an age of ca. 60 ka. These also relate to a major glacial advance during Oxygen Isotope Stage 3. A younger series of moraines, the Jalipur Tillite, and glaciofluvial sands at Liachar in the Indus valley, and moraines at Rampur–Tarshing have ages of ca. 27 ka, ca. 21–23 ka and ca. 15 ka, respectively. These dates show that glaciers also occupied parts of the Indus valley during Oxygen Isotope Stage 2. These dates and the morphostratigraphy show that glaciation in the Pakistani Himalaya was more extensive during the early part of the last glacial cycle and that the local last glacial maximum in Pakistan was asynchronous with the maximum extent of Northern Hemisphere ice sheets. Copyright © 2000 John Wiley & Sons, Ltd.     

萨拉乌苏河流域地层沉积时代及其反映的气候变化

萨拉乌苏河流域位于我国北方沙漠/黄土过渡带和生态脆弱带,它对全球变化反映非常敏感,是研究全球变化的理想区域。本文根据地质测年、气候地层对比,以及地层中气候代用指标的分析,将萨拉乌苏河流域地层和气候变化划分为全新统的风成相与湖相沉积(0~11.5kaBP),早、中期气候较暖湿,晚期气候较干旱;上更新统城川组的风成相沉积(11.5~80kaBP),气候干旱寒冷;上更新统萨拉乌苏组的湖相沉积(80~140kaBP),气候温暖较湿润;中更新统上部的河流相与风成相互层(140~190kaBP),气候冷干与温凉半干旱波动;中更新统上部的冲洪积沉积(190~220kaBP),气候较暖湿等阶段。指出自中更新世晚期以来气候发生频繁波动,无论是暖湿还是冷干阶段,气候都波动频繁,气候变化不稳定性明显。     

A lacustrine record from Lop Nur,Xinjiang, China: Implications for paleoclimate change during Late Pleistocene

Climate variability during the Late Pleistocene is studied from the proxies in core CK-2 drilled from the Luobei Depression (91°03′E, 40°47′N), Lop Nur in the eastern Tarim Basin, Xinjiang, China. Geophysical and geochemical properties, including magnetic susceptibility, granularity, chroma, carbonate content, loss on ignition and trace elements, have been determined to reconstruct the environmental evolution of the area during 32–9 ka BP. The chronology is established by uranium–thorium disequilibrium dating techniques.Our data suggest four paleoclimate stages, indicating glacial variations between cold–humid and warm–arid environments. A period of extreme humidity occurred during 31,900–19,200 yr BP is attributed the last glacial maximum (LGM). The period was followed by a warm–arid episode during 19,200–13,500 yr BP. Then a cold–humid interval during 13,500–12,700 yr BP may correspond to another cooling phases at high latitudes of the Northern Hemisphere. The last stage from 12,700 to 9000 yr BP has a trend that the climate turned warm and arid. The Lop Nur region is characterized by particularly humid stadials and arid interstadials. The climate variability in Lop Nur was constrained by global climate change because it is correlated with Dansgaard–Oeschger and Heinrich events, which were observed at the northern high latitudes. The synchroneity of the palaeoclimatic events suggested that cold air activity at the northern high latitudes was the most important factor that influenced the climate evolution in the Lop Nur region. A probable mechanism that involves the migration of westerly winds is proposed to interpret this synchroneity.     

Paleoclimatic interpretation of the past 30 ka from isotopic studies of the deep confined aquifer of the North China plain

The δ¹⁸O and δD values in the deep confined aquifer beneath the North China Plain which is located at 112°30′E–119°30′E and 34°46′N–40°25′N, reflect differences in paleoclimatic conditions between the Holocene and the late Pleistocene. Groundwater samples whose ¹⁴C ages are between 12 and 25 ka B.P have ranges of −9.4 to −11.7‰ for δ¹⁸O and −76‰ to −85‰ for δD values. These very negative δ¹⁸O and δD values reflect the cold and arid climate in the last glacial period. The temperature estimated in this period is 6–9 °C cooler than that of the present. The entire ranges of δ¹⁸O and δD values for samples with ¹⁴C dating from 7 ka B.P to present are −7.7‰ to −10.2‰ and −63‰ to −73‰, respectively. The greater δ¹⁸O and δD enrichments of these samples indicate a period of relatively humid and warm climate in the Holocene. However, the wide ranges of δ¹⁸O (−9.0‰ to −11.1‰) and δD (−66‰ to −80‰) values for samples with ¹⁴C age ranging from 12 to 7 ka B.P. imply an unstable climatic condition of rapidly increasing temperature, which marks the transition from the Pleistocene to the Holocene.     

The loess-paleosol and related subaereal sequence in Hungary

The loess of type localities is subdivided into 3 subseries on the basis of the paleosols allowing even an Eurasian comparison for their lithostratigraphy.

1. The upper young loess (8–10 m) is most widespread, characterized by 3 sandy loess and 2 intercalated humic loess horizons. The ages of the humic loess horizons H₁, H₂ are c. 16 ka and 20 ka BP, respectively.
2. The lower young loess (15–20 m) contains 4 loess packets and 3 chernozem-like paleosols, usually doubled soil complexes (designated MF, BD, BA). The MF paleosol complex, first member of lower young loess is c. 27–28 ka BP (C¹⁴ and TL dating). The lower young loess is underlain by a brown forest soil and chernozem-like paleosol-assemblage (MB), probably formed during the last interglacial (c. 105–125 ka BP).
3. The old loess (c. 20 m) is generally characterized by 6–7 loess, mainly brown forest soil and 2 interbedded fluvial sand layers. The lowermost old loess member and an ochre-red paleosol lie below the Brunhes-Matuyama boundary (0,73 Ma).
4. The loess is underlain by a subaerial non-loessic sequence (20–40 m) with 5–10 red soils, red clays mostly directly superimposed on and locally interbedded by sand and silty sand. At the base of this sequence of red paleosols usually Uppermost Miocene inland sea deposits are found.

It can be concluded that the reddish paleosol developed under climatic, and in general, ecological conditions (probably warm subhumid with rapid cyclical climatic changes) differing from the cold and semiarid or semidesert environments of typical loess formation. The former conditions were characteristic — from the Lower Pliocene to the Lower Pleistocene — on continental or global scales.     

Extinction chronology of the cave lion Panthera spelaea

The cave lion, Panthera spelaea, was widespread across northern Eurasia and Alaska/Yukon during the Late Pleistocene. Both morphology and DNA indicate an animal distinct from modern lions (probably at the species level) so that its disappearance in the Late Pleistocene should be treated as a true extinction. New AMS radiocarbon dates directly on cave lion from across its range, together with published dates from other studies – totalling 111 dates – indicate extinction across Eurasia in the interval ca. 14–14.5 cal ka BP, and in Alaska/Yukon about a thousand years later. It is likely that its extinction occurred directly or indirectly in response to the climatic warming that occurred ca. 14.7 cal ka BP at the onset of Greenland Interstadial 1, accompanied by a spread of shrubs and trees and reduction in open habitats. Possibly there was also a concomitant reduction in abundance of available prey, although most of its probable prey species survived substantially later. At present it is unclear whether human expansion in the Lateglacial might have played a role in cave lion extinction. Gaps in the temporal pattern of dates suggest earlier temporary contractions of range, ca. 40–35 cal ka BP in Siberia (during MIS 3) and ca. 25–20 cal ka BP in Europe (during the ‘Last Glacial Maximum’), but further dates are required to corroborate these. The Holocene expansion of modern lion (Panthera leo) into south-west Asia and south-east Europe re-occupied part of the former range of P. spelaea, but the Late Pleistocene temporal and geographical relationships of the two species are unknown.     

OSL and TL dating of buried podsols and overlying sands in Ostrobothnia,western Finland

In Ostrobothnia, western Finland, buried fossil soils have been recognised in a number of places in the sandy sediments that occur between glaciofluvial deposits and overlying till. Samples from the soil horizons as well as below and above them were taken for optically stimulated luminescence (OSL) dating. The same sites were also sampled for thermoluminescence (TL) dating. Altogether five TL dates and seventeen OSL dates were obtained. The OSL dates can be grouped into two age classes, (i) 120-163 ka and (ii) 76-106 ka, whereas all TL dates are of the order 135-155 ka. A comparison between the results obtained from the two dating methods shows that OSL dates are generally younger than the TL dates for the same sample. The discrepancy may arise partly from problems of setting a correct residual level in TL dating. If this is the case then the TL dates may indicate an upper limit for the true age. The results support the geological interpretation that the fossil soils were formed during the last interglacial, that the soil-forming processes possibly also continued during the first Early Weichselian stadial and interstadial (Brørup sensu lato), and that in general the till-covered glaciofluvial sequences, interpreted as eskers in Ostrobothnia, were deposited during the Saalian or Early Weichselian deglaciation.