Timing of Late Pleistocene climate change in lowland Switzerland

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Quaternary Science Reviews 22 (2003) 1435–1445

Timing of Late Pleistocene climate change in lowland Switzerland Frank Preusser*, Mebus A. Geyh1, Christian Schluchter . Institut fur . Geologie, Universitat . Bern, Baltzerstrasse 1-3, CH-3012 Bern, Switzerland Received 11 January 2002; accepted 1 April 2003

Abstract A chronology of climate change in lowland Switzerland for the time between the Last Interglacial and the Last Glaciation Maximum (LGM) is provided by complementary radiocarbon, 230Th/U and luminescence dating of the Gossau key section. The Gossau-Interstadial-Complex is consistently dated to B50,000–30,000 yr BP and hence correlated with Marine Oxygen Isotope Stage (MIS) 3. Palaeotemperature readings reconstructed from coleoptera analyses and pollen assemblages evidence oscillating environmental conditions from tundra to open woodland and reflect changing climate during the Middle Wurmian. . Delta deposits from the lower part of the Gossau section indicate a cold period prior to the Interstadial-Complex. This severe climatic deterioration is correlated with MIS 5d based on luminescence dating. Sedimentological evidence implies the presence of glaciers at the northern margin of the Swiss Alps during this time. r 2003 Elsevier Science Ltd. All rights reserved.

1. Introduction A growing number of palaeoclimatic archives covering the Last Glacial/Interglacial cycle have been investigated on the European continent. Such records are reasonably well established for areas such as France (Woillard, 1978; Beaulieu and Reille, 1989, 1992), central and southern Italy (Follieri et al. 1998; Allen et al., 1999), and NW central Europe (Behre and Lade, 1986; Huijzer and Vandenberghe, 1998; Caspers and Freund, 2001). For the southern part of central Europe, the northern foreland of the Alps, detailed information about past vegetation changes is available from key sites such as Samerberg (Gruger, . 1979), Mondsee (Klaus, 1987; Drescher-Schneider 2000), Gondiswil (Wegmuller, . 1992), and Meikirch (Welten, 1982, 1988). None of these sites, however, shows a well-developed record of the Middle Wurmian . (ca 56,000–30,000 yr BP). Nevertheless, this time period is of particular interest for palaeoclimatic reconstructions because of the likely impact of rapid climate change, as reported from Greenland ice-cores (Johnsen et al., 1992; Dansgaard et al., 1993), on terrestrial environments of central Europe. *Corresponding author. E-mail address: [email protected] (F. Preusser). 1 Previously at: Institut fur . Geowissenschaftliche Gemeinschaftsaufgaben (GGA), Stilleweg 2, D-30 655 Hannover, Germany.

Another major issue concerning the Last Glacial history of the Alps is an on-going discussion about glacier advances onto the lowland subsequent to the Last Interglacial but prior to the Last Glacial Maximum (LGM, B20,000 yr) (Welten, 1981; Schluchter, . 1991, 1992; Wegmuller, . 1992; Keller and Krayss, 1998). Lacking any direct dating evidence, the existence of such glacial advances remains uncertain but seems to be significant in the context of understanding the complexity of changes in Pleistocene climate and atmospheric circulation. One site providing significant information regarding these two topics was previously exposed in a gravel pit near Gossau, Switzerland. This paper summarises the available data from this key site and presents some additional luminescence ages. The palaeoclimatic information from Gossau and other sites in lowland Switzerland is discussed on a regional and European scale.

2. The Gossau site The section was exposed in a gravel quarry near Gossau (Kanton Zurich), . a few kilometres east of Zurichsee . (Lake Zurich) . (Fig. 1). The upper part of the sequence consists of outwash gravel and lodgement till deposited during the LGM. Peat horizons inter-

0277-3791/03/$ - see front matter r 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0277-3791(03)00127-6

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Fig. 1. Location of the Gossau gravel pit, Switzerland and area covered by ice during the LGM (Wurmian). .

calated with overbank deposits and weathered gravel (Gossau-Interstadial-Complex) occurs below the glaciofluvial/glacigenic deposits (Fig. 2). The organic beds provide climatic information derived from pollen assemblages and are dated using the radiocarbon method (Schluchter . et al., 1987) (Table 1). The radiocarbon dates lead to a correlation of the GossauInterstadial-Complex with Marine Isotope Stage (MIS) 3. This correlation is further verified by 230Th/U and luminescence dating (Geyh and Schluchter, . 1998; Preusser, 1999a) (Table 1, Fig. 3). Additional palaeoenvironmental information is provided by coleoptera analysis (Jost-Stauffer, 2001; Jost-Stauffer et al., 2001). The lower part of the section consists of gravel and sand of proximal-deltaic origin deposited in a cold climate environment as indicated by pollen assemblages (Betula, Artemisia, Juniperus) and sediment facies analysis (Schluchter . et al., 1987). The distal part of the same delta, consisting of fine-grained sand and silt, was exposed in a second pit within the quarry. The sequence of deltaic sediments overlain by organic deposits apparently represents a continuous sedimentation process, a basin in-fill resulting in a swamp-facies environ-

ment. Based on this geological context the delta sediments are correlated with MIS 4 (Schluchter, . 1991). This assumption and evidence from several other sections in lowland Switzerland imply a glaciation, less pronounced than the LGM, which occurred subsequent to the Last Interglacial (Eemian), but prior to the glacial advances during MIS 2 (Schluchter, . 1991, 1992).

3. Luminescence dating 3.1. Sample locations A first set of luminescence ages was determined by applying the polymineral fine-grain technique (samples GOS 1–4: Preusser, 1999a). For the Gossau-Interstadial-Complex, these ages (GOS 3, 4) agree well with the results of radiocarbon and 230Th/U dating (Fig. 3). For the delta sediments, luminescence ages of B100,000 yr are significantly higher than the expected age of B65,000 yr (Preusser, 1999a). Although, luminescence ages determined for two different samples (GOS 1, 2) from sandy layers within the delta forest agreed well

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Fig. 2. Schematic sketch of the Gossau section showing the location of samples taken for luminescence dating. Sedimentological units after Schluchter . et al. (1987): (1) sediment overprinted by Holocene soil formation; (2) glacial diamict, lodgement till; (3) proximal-glacial gravel; (4) silt, overbank deposit; (5) compressed peat; (6) poorly sorted gravel, upper part indicating soil formation; (7) gravel with sand layers, proximal delta facies; (8) silt with some stones, delta top sets; (9) fine sand, distal delta facies, (10) silty sand, delta bottom sets.

Table 1 14 C (AMS) and

Th/U ages for the Gossau-Interstadial-Complex (from Schluchter . et al., 1987; Geyh and Schluchter, . 1998)

230

Stratigraphic position

Laboratory Number

14 C age (yr BP)

Calibrated 14C age (yr cal. BP)

230 Th/U (yr BP)

Uppermost humic horizon

UZ-2209/ETH-2205 UZ-2120/ETH-849 UZ-2210/ETH-2206

28,5507310 29,45071150 28,2507350

B32,200 B32,750 B31,850

34,70074000

Upper humic horizon Upper layer Lower layer

UZ-2211/ETH-2207 UZ-2121/ETH-850 UZ-2212/ETH-2208

33,4107480 33,00072500 40,29071120

B34,100–35,100 B33,700–34,700 B42,300

Lower humic horizon Upper layer Lower layer

UZ-2213/ETH2209 UZ-2122/ETH-851 UZ-2214/ETH-2210

45,40071200 47,50071800 54,000773000

B48,000 B50,500 n.a.

37,60071700 47,80076000

49,40073300

Calibration of radiocarbon dates follows the method of Geyh and Schluchter . (1998).

within errors, further dating was carried out to verify this age estimate. The multiple-aliquot technique was applied to quartz and K-rich feldspar grains, respectively, separated from samples GOS 1 and GOS 2. Additionally, three samples (GOS 5–7) from the top sets of the delta complex and three samples (GOS 8–10) from the distal part of the delta were taken (Fig. 2).

3.2. Methodological approach Basic information on the luminescence dating techniques is provided by e.g. Aitken (1998) and Wintle (1997). Dating was carried out using infrared stimulated luminescence (IRSL), green-light stimulated luminescence (GLSL), and thermoluminescence (TL) techniques.

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Fig. 3. The Gossau-Interstadial-Complex with vegetation type (Burga and Perret, 1998) and estimated mean July temperature (Jost-Stauffer et al., 2001, in press), 14C, 230Th/U and luminescence mean ages. Tentative correlations with northern central Europe (Caspers and Freund 2001), La Grande Pile (Beaulieu and Reille, 1992) and Lago Grande di Monticchio (Allen and Huntley, 2000; Allen et al., 2000) are shown.

Detailed information on laboratory procedures used for the determination of the equivalent dose is provided by Preusser (1999a, b) and Preusser et al. (2001). The concentration of dose rate relevant elements (K, Th, U) (Table 2), as needed for the calculation for the dose rate, was carried out by high-resolution gamma spectrometry (Preusser and Kasper, 2001). One potential problem for dating samples from fluvial environments is incomplete zeroing of the luminescence signal prior to deposition. Dating samples from incompletely bleached sediments will result in overestimation of the actual age. However, some criteria can be used as indicators for well-bleached sediments. First, it is expected that in poorly bleached sediments silt-sized and sand-sized grains will show different levels of residual luminescence due to their specific transport modes in water (Murton et al., 1997; Aitken, 1998; Wallinga, 2002). Corresponding ages for the two different grain-size fractions are thus interpreted to indicate complete bleaching of the luminescence signal prior to deposition. In our dating approach, ages were determined for polymineral fine-grains (4–11 mm) as well as for coarse-grained (100–200 mm) K-rich feldspar and quartz samples, respectively. Second, time and intensity of sunlight exposure varies for each individual layer in the Gossau section due to spatial and temporal fluvial dynamics. Incompletely bleached samples are thus likely to inherit different levels of residual luminescence prior to deposition. Dating of different samples from the same

stratigraphic member will thus result in diverging age estimates. Consequently, conforming ages are expected to indicate well-bleached sediments. Third, comparison of luminescence signals with different bleaching characteristics would be another appropriate test (Fuller et al., 1994). However, laboratory experiments have shown no significant differences in the bleaching characteristics of the different IRSL and GLSL signals of the Gossau samples (Preusser, 1999c). One can use only the comparison of IRSL and TL but this approach will be limited to very well bleached sediments and is probably not suitable for samples from most fluvial environments. Another potential error in luminescence dating is a systematic age underestimation of sediments, especially when dating feldspars from deposits older than B100,000 yr. This age shortfall is explained by instabilities of some parts of the luminescence signal and is known as long-term fading (Mejdahl, 1988). However, while fading can be significant for one geological source area, it may be completely absent in other regions. Consequently, long-term fading properties have to be investigated for any particular geological province. Comparison with ages derived by other dating methods is one appropriate test. Furthermore, the various components of the luminescence signal are expected to have different long-term fading characteristics (Balescu and Lamothe, 1992; Krbetschek et al., 1997). For some selected samples from Gossau, luminescence ages were

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Table 2 Radioactivity data and resultant dose rates for luminescence dating Sample

K (%)

Th (mg g
1)

U (mg g
1)

Moisture (%)

Cosmic (mGy kyr
1)

D–F (Gy kyr
1)

D–Q (Gy kyr
1)

D-FGIRSL (Gy kyr
1)

D-FGTL (Gy kyr
1)

GOS1 GOS2 GOS3 GOS4 GOS5 GOS6 GOS7 GOS8 GOS9 GOS10

0.6770.03 0.7270.04 1.0470.05 1.0370.05 1.1970.06 0.9470.05 1.3370.06 0.8070.04 0.7670.04 0.7870.04

3.4270.17 3.0970.15 9.4670.47 8.2170.41 8.7770.44 7.6370.38 7.0370.35 5.8170.29 4.3670.21 5.1570.26

1.4970.08 1.5670.08 2.8070.14 2.6870.13 2.9970.15 2.7970.14 2.6970.13 2.5170.13 2.0970.10 2.3470.12

1274 1274 2075 2075 2075 2075 1274 1274 1274 1274

8078 9079 110711 135714 100710 100710 100710 100710 9079 8078

1.870.2 1.870.2 — 2.670.2 — — 2.970.2 2.370.2 2.170.2 2.270.2

1.470.1 1.570.1 — — — — — — — —

1.570.1 1.670.1 2.770.2 2.570.2 2.770.2 2.470.2 2.970.2 2.370.1 1.970.1 2.170.1

1.570.1 1.770.1 2.970.2 2.670.2 2.870.2 2.570.2 3.070.2 2.470.1 2.070.1 2.27 0.2

Concentrations of dose relevant elements were determined by high-resolution gamma spectrometry (Preusser and Kasper, 2001). Relative moisture was estimated on the basis of present day water content and sediment composition. The contribution of cosmic radiation to the dose rate was calculated by adapting present day sediment depth. The resulting dose rates are shown for feldspars (D–F), quartz (D–Q) and the fine grain fraction (D-FGIRSL, D-FGTL).

determined for four different emission bands of IRSL from polymineral fine-grains and potassium rich feldspars as well as for GLSL of quartz. 3.3. Results and discussion A total of 76 luminescence ages are determined by applying several stimulation sources, grain-sizes and the detection of the luminescence emissions at different wavelengths (Table 3). Short-term fading tests did not show any loss of IRSL intensities over a period of 1 yr (Preusser, 1999b). Four additional ages for sample GOS 4 determined using K-rich feldspars confirm IRSL ages of B30,000 yr calculated for fine-grains. The results for both techniques agree well with calibrated radiocarbon ages of B32,000 yr for peat located just below the overbank deposit. For the samples taken from the delta sediments (GOS 1–2, 5–10), the TL ages are significantly older than ages determined by IRSL and GLSL. This is reasonably well explained by the lesser light sensitivity of the TL signal (Godfrey-Smith et al., 1988). Thus, the TL ages are interpreted to be overestimated due to incomplete bleaching of the TL-signal prior to deposition and are not considered in the discussion of the age of the delta sediments. For the identification of partial bleaching, IRSL ages determined for different grain-sizes and different samples are compared. The comparison shows for the majority of samples no significant difference between the ages determined for sand and silt-sized grains and for different samples from the delta complex (Fig. 4). Consequently, it is assumed that the IRSL signal in all samples was zeroed prior to deposition. However, the possibility of age underestimation due to long-term fading also needs to be considered. Two previous studies show that sediments from the Alpine Foreland can be dated throughout the Last Glacial cycle

without any age shortfall. First, a mean IRSL age of 96,000 yr determined for fine-grained fluvial sediments from the Zell gravel pit, central Switzerland (Preusser et al., 2001), agrees well with the mean 230Th/U age (95,000 yr) of associated peat (Kuttel, . 1989; Geyh et al., 1997). Second, an IRSL age of 134,800711,400 yr (Erfurt et al., 2003, submitted) for sandy layers associated with sinter deposits near Hurlach, Lech Valley, Bavaria, corresponds well with a 230Th/U age of 120,40076000 yr (Jerz and Mangelsdorf, 1989). Additionally, the weighted mean ages for the different K-feldspar emissions and for quartz from the Gossau site are nearly identical (Table 4). When considering that the different emissions are expected to have different fading characteristics, it is concluded that the IRSL and GLSL ages do reflect the absolute age of the sediment. Following this argument, the delta deposits are interpreted as considerably older than MIS 4, as previously expected. A significant hiatus between the delta sequence and the lower peat is also indicated by the decalcified upper part of the delta top-sets. According to the luminescence dates the delta sediments were deposited just after the Last Interglacial, at the onset of the Last Glacial cycle.

4. The Last Glacial cycle in lowland Switzerland The luminescence ages of the delta sediments from Gossau indicate a period of cold climate just after the Last Interglacial. The presence of a high amount of relatively fresh alpine clasts within the gravel implies the presence of a glacier in the catchment area during delta formation (Schluchter . et al., 1987). An early Wurmian . glaciation of lowland Switzerland is already discussed on the basis of sedimentological observations from several sites (Welten, 1988, Schluchter, . 1989, 1992;

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Table 3 Luminescence ages of the Gossau samples determined from different grain-size fractions and various techniques Sample GOS1

Mineral technique 4–11 mm fine grains IRSL

100–200 mm K-feldspar IRSL

GOS2

100–200 mm quartz GLSL 4–11 mm fine grains IRSL

100–200 mm K-feldspar IRSL

GOS3

GOS4

100–200 mm Quartz GLSL 4–11 mm fine grains IRSL

4–11 mm fine grains IRSL

100–200 mm K-feldspar IRSL GOS5 GOS6 GOS7

GOS8

GOS9

GOS10

4–11 mm fine grains, IRSL 4–11 mm fine grains, IRSL 4–11 mm fine grains, IRSL 100–200 mm K-f.sp., IRSL 4–11 mm fine grains, IRSL 100–200 mm K-f.sp., IRSL 4–11 mm fine grains, IRSL K-f.sp., IRSL fine grains, IRSL 100–200 mm K-f.sp., IRSL

Emission, method

EDOSL (Gy)

OSL age (kyr)

EDTL (Gy)

TL age (kyr)

a

203728 167718 158720 167713 141749 170719 224717 183715 155717 231729 156729 116733 240737 174714 165718 179724 164716 173714 167715 211726 148726 241726 117736 119745 129711 127713 138716 138710 132716 93714 77711 7676 7378 7872 7876 7377 8077 6373 321736 293725 320.6736.1 293.4725.4 314745 326733 282734 257726 268733 199773 235761 184716 183733 219744 279734 259733 342743 171720 233716

132719 108717 103718 105714 91733 96712 127715 104713 87713 142719 111722 82724 151725 110711 104713 113717 103712 95712 92712 116718 82710 144717 80725 82731 4976 4876 5277 5275 5077 3776 3075 3073 2974 3172 3173 2974 3274 2572 116716 106712 153727 136730 107716 111713 96713 89711 118716 88733 102728 8079 95718 113724 136720 123717 162723 79711 107711

785771 333770 No sol. 300772 No sol. — — — — — — — No sol. 723752 No sol. 309736 266724 — — — — — — — 146720 137710 185763 170717 140713 109724 112713 105744 70715 65714 — — — — No sol. 288737 No sol. 4787128 No sol. 440746 — — No sol. 3697176 — — No sol. 594787 — No sol. No sol. — —

509774 209751 — 173751 — — — — — — — — — 426740 — 182724 157717 — — — — — — — 5178 4876 64723 5978 5176 41710 4376 40717 2776 2575 — — — — — 100715 — 191753 — 145718 — — — 156775 — — — 296747 — — — — —

BB, add BB, rega Yellow, adda Blue, adda uv, adda BB, add Yellow, add Blue, add uv, add UV, add UV, add UV, add BB, adda BB, rega Yellow, adda Blue, adda uv, adda BB, add Yellow, add Blue, add uv, add UV, add UV, add UV, add BB, adda BB, rega Yellow, adda Blue, adda uv, adda BB, adda BB, rega Yellow, adda Blue, adda uv, adda BB, add Yellow, add Blue, add uv, add Yellow, add Blue, add Yellow, add Blue, add Yellow, add Blue, add Yellow, add Blue, add Yellow, add Blue, add Yellow, add Blue, add Yellow, add Blue, add Blue, add Yellow, add Blue, add Yellow, add Blue, add

Dating was undertaken applying IRSL/TL on polymineral fine grains (4–11 mm), IRSL on K-feldspar (100–200 mm) and GLSL on quartz (100– 200 mm), respectively. IRSL was detected at four different emission ranges of the luminescence spectrum (filter: BB (broad band)=BG39; yellow=BG39/OG530; blue=BG39/7-59/GG400; UV=U340). add=additive dose method, reg=regeneration method, no sol.: no solution in growth curve fitting (luminescence signal at saturation). a Previously published by Preusser (1999a).

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Table 5 Stratigraphy of the last glacial cycle in the Swiss Alpine Foreland (after Welten, 1982; Wegm.uller, 1992) Welten (1982)

Wegm.uller (1992)

Vegetation

MIS

Holocene Turicum 6 Turicum 5

Holocene

Temperate forest Tundra/Glaciation

Z.alga Widena

Poorly known

. Durnten Bifig Ufhusen Muhle . Huttwil Seilern Gondiswil Ibach

Boreal forest Wooded steppe Boreal forest Wooded steppe Boreal forest Tundra Temperate forest Tundra

1 2 3 3 3 3 3 4 5a 5b 5c 5d 5e 6

Turicum 4 . Durnten Turicum 3 2. Interstadial Turicum 2 1. Interstadial Turicum 1 Riss/Wurm . Rissian

Fig. 4. Comparison of IRSL ages determined for silt- and sand-sized grains (blue and yellow emissions).

Table 4 Statistical data of GLSL and IRSL ages determined for samples from the delta complex at Gossau. Weighted mean age, standard deviation and standard error have been calculated for the different methods used Method

GLSL (quartz) IRSL (blue) IRSL (yellow) All data

n

w2

Weighted mean (kyr)

Standard Standard deviation error (kyr) (kyr)

6

117

31

13

9.9

14

103

18

5

20.5

13

104

17

5

15.1

42

103

18

3

58.8

Keller and Krayss, 1998). Likewise, pollen profiles indicate a severe climatic recession (Turicum 1) and a replacing of forest by tundra vegetation following the Last Interglacial (Welten, 1981, 1982; Wegmuller, . 1992). However, evidence of the extension of the ice margin is poorly preserved as most of the remains of this older glacial advance were subsequently overrun and reworked by ice during the LGM. This first period of cold climate during the early Wurmian . was followed by the Huttwil Interstadial (Table 5) that is characterised by boreal forests with Picea abies and Pinus (Welten, 1982; Wegmuller, . 1992). 230 Th/U ages for this interstadial are available for the . sections of Beerenmosli (94,00075000 yr; Wegmuller, . 1992; Geyh et al., 1997) and Zell (95,00073000 yr; Kuttel, . 1989; Geyh et al., 1997). Fluvial deposits associated with the peaty horizons at Zell have a mean

MIS age (kyr) 11 24

57 71 86 97 106 122 127 186

Correlation with Marine Isotope Stages (MIS) after Wegmuller . (1992). MIS ages refer to the beginning of the (sub-)stage after Bassinot et al. (1994). a Note that the exact age of Widen and Z.alg interstadials is not known.

IRSL age of 96,00074000 yr (Preusser et al., 2001). These ages imply a correlation of the Huttwil Interstadial with MIS 5c. Several pollen records show another stadial interval (Turicum 2) and an interstadial with boreal forest vegetation (Picea/Pinus), known as Ufhusen, subsequent to the Huttwil Interstadial. This second interstadial is commonly correlated with MIS 5a (Welten, 1982; Wegmuller, . 1992) but no geochronological data are available to support this correlation. In the pollen records, the Ufhusen Interstadial is followed by a significant cooling episode that marks, by definition of the Sub-Commission on European Quaternary Stratigraphy, the beginning of the Middle Wurmian . (Chaline and Jerz, 1984). A third interstadial bearing boreal forest vegetation, known as Durnten . (Welten, 1982), is commonly considered as the last interval of temperate climate prior to the LGM. While some authors correlate the Durnten . Interstadial with late MIS 5 (e.g. Muller, . 2001) others favour a younger, MIS 3 age for the interstadial (e.g. Wegmuller, . 1992). The correlation with early MIS 3 is supported by IRSL ages (50,000–60,000 yr) on sediments from the Galgenmoos site, central Switzerland (Wegmuller . et al., 2002). Furthermore, recent speleothem evidence from the Austrian Alps confirms the existence of a pronounced interstadial, with a mean temperature only a few degrees . and Mangini, below present, during early MIS 3 (Spotl 2002). The Gossau-Interstadial-Complex is, for the time being, the most complete palaeoclimate record of MIS 3 in lowland Switzerland (Fig. 3). The basal part of the lowermost peat (PZ 2) has a conventional radiocarbon age of 54,000 yr and is thus at the upper limit of the

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method. Vegetation of open woodland type is indicated by the presence of pollen of Picea abies, Pinus, Betula, Alnus and Picea omorica-type (Burga and Peret, 1998). Reconstructions based on coleoptera analyses indicate a calibrated mean July temperature (TMax ) of about 13 C during this Picea Interstadial. Mean temperature during the coldest month (TMin ) was about
10 C (JostStauffer, 2001). Such climatic conditions would have allowed the growth of forest vegetation in the area. Stems of wood found in the lower peat support the presence of trees at the site. From the pollen assemblages, this interstadial was characterised by a climate that was less temperate than during the Huttwil and Ufhusen Interstadials, implying a correlation with the Durnten . Interstadial (Burga and Peret, 1998). However, the palynological features of the first Picea Interstadial at Gossau differ significantly from those of the Durnten . Interstadial sensu stricto and a correlation of these two intervals is still controversial (Wegmuller . et al., 2002). The first Picea Interstadial at Gossau was followed by a period of forest steppe vegetation (PZ 3; Pinus, Betula, Artemisia, Graminae). For this layer, two radiocarbon ages of 45,40071200 and 47,50071800 yr BP are available, representing absolute ages of about 48,000– 50,000 yr when applying the calibration of Geyh and Schluchter . (1998). Coleoptera assemblages indicate a decrease of TMax to 8 C and of TMin to
20 C and explain the decline of woody vegetation (Jost-Stauffer, 2001). The second Picea Interstadial (PZ 4; Picea abies, Pinus cembra, Picea omorica-type) has a calibrated radiocarbon age of 42,300 BP and a 230Th/U age of 47,80076000 yr. Paleotemperatures of 13 C (TMax ) and
10 C (TMin ), respectively, are estimated for PZ4 and are consistent with the palynological evidence indicating relative temperate climatic conditions. The stalagmite record from the Kleegruben cave in Austria also indicates a temperate period starting after 47,000 yr . and Mangini, 2002). On top of the interstadial (Spotl deposits at Gossau a thin overbank deposit interrupted peat growth. The reconstructed TMax and TMin for this sediment are 9 C and
11 C, respectively. The following period of forest-steppe vegetation (PZ 5) at around 35,000 yr ago was dominated by Pinus and Betula and with TMax ¼ 10 C and TMin ¼
11 C (Jost-Stauffer, 2001). A significant break in sedimentation is evidenced by the presence of gravel and diamictic slope wash deposits on top of the peat (PZ 6). Forest vegetation was completely absent as only non-tree pollen (e.g. Gramineae, Artemisia) are found (Schluchter . et al., 1987). The upper part of these deposits is overprinted by arctic soil forming processes (B. van Vliet-Lano.e, pers. comm.). The uppermost humic horizon (PZ 7; ca 32,000 yr 14C cal. BP) was deposited at a TMax of 9 C and a TMin of
21 C, respectively (Jost-Stauffer et al., 2001). The Gossau site was a tree less swamp-floodplain during PZ7 and the input of tree-pollen (Pinus) may originate from

small patches of woodland refugia in the surrounding area. However, even these harsh environmental conditions had an interstadial character compared to climate during the LGM, which had an estimated TMax of about 0 C (Caspers and Freund, 2001). The last advance of the Alpine glaciers into lowland Switzerland must have taken place after about 30,000 yr as inferred from the age of the top of the Gossau-Interstadial-Complex. The maximum extent of the LGM occurred at about 20,000 yr as indicated by surface exposure dating of erratic boulders from remains of the Rhone glacier at Wangen an der Aare (Ivy-Ochs, 1996). Similar radiocarbon ages were determined for bone fragments from glaciofluvial outwash connected to the maximum extent of the Rhine glacier (Geyh and Schreiner, 1984).

5. Comparison of the Gossau-interstadial-Complex with other European palaeoclimate records Tentative correlations of the Gossau-InterstadialComplex with other pollen stratigraphies of Europe are shown in Fig. 3. The Middle Weichselian interstadials of NW central Europe (northern Germany, The Netherlands) are all characterised by shrub and grass pollen and cannot be distinguished by their vegetation features but by radiocarbon dating only (Behre and Lade, 1986). In contrast, the deposits of the GossauInterstadial-Complex show well-defined interstadials and cold periods as indicated by sedimentological features, pollen assemblages and coleoptera analysis. The radiocarbon date for the first Picea Interstadial (PZ 2) at Gossau is similar to radiocarbon ages determined for the Oerel Interstadial in northern Germany (Behre and van der Plicht, 1992). However, due to the limited number of dates and considering the upper dating limit of the radiocarbon method such a correlation remains tentative. For the Oerel Interstadial, a mean July temperature of 9 C is reconstructed based on coleoptera data (Walkling, 1997). The July temperature is thus about 4 C lower than at Gossau, if the correlation of the first Picea Interstadial with the Oerel is correct. The subsequent period of wooded steppe (PZ 3) at Gossau is also not easily correlated with the NW European stratigraphy. Considering the radiocarbon ages determined for the Glinde Interstadial (51,000–48,000 yr BP) (Behre and van der Plicht, 1992), the dates for PZ 3 at Gossau (Table 1) seem to be slightly younger. However, it is difficult to judge whether this is caused by uncertainties involved with the dating procedures of the different radiocarbon laboratories or if the deposits at Gossau are really considerably younger. Thus, a correlation with the early part of the Moershoofd Interstadial Complex is also possible. For this period, reconstructions of mean July temperature in NW Europe range between 7 C and 13 C (see discussion in

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Huijzer and Vandenberghe, 1998; Caspers and Freund, 2001). Similar changes in mean July temperature (8– 11 C) are also evidenced for PZ 3 at Gossau (Fig. 3). The radiocarbon ages for the second Picea Interstadial (PZ 4) correspond reasonably well to those determined for the Hengelo Interstadial. The mean July temperature reconstructed for the Hengelo is about 10–12 C (Kasse et al., 1995) and is slightly lower than TMax of 13 C, as calculated for Gossau. Dating results for the upper peat (PZ 7) match reasonable well with those of the Denekamp Interstadial and a mean July temperature of just below 10 C (Caspers and Freund, 2001) is similar to that calculated for Gossau. One of the best investigated palaeoclimatic records of Europe is the site at La Grande Pile, Vosges, eastern France (Woillard, 1978; Beaulieu and Reille, 1992). The site is approximately 150 km northwest of Gossau and should show a similar climatic history. The record from La Grande Pile, however, shows some distinct differences in vegetational features as records from the Alpine Foreland. The interstadials St. Germain I and St. Germain II at La Grande Pile are characterised by vegetation of a warm temperate forest with Carpinus and Quercus (Woillard, 1978), while boreal forest with Picea and Pinus grew at the same time in Switzerland (Table 5). There is also no equivalent of the pronounced third Last Glacial interstadial (Durnten) . at La Grande Pile, although this temperate phase has been identified in several pollen records from Switzerland (Welten, 1982; Wegmuller, . 1992), northern Austria (Drescher-Schneider, 2000) and southern Germany (Gruger, . 1979; Muller, . 2001). It is concluded that the sequence at La Grande Pile is probably at least partially not continuous (Beaulieu and Reille, 1989, 1992; Ponel, 1995). On basis of the dating results, a tentative correlation of PZ 2 and/ or PZ 3 from Gossau with the Pile Interstadial, with a radiocarbon age of 49,80071500 yr (Woillard and Mook, 1982), seems to be most likely. The area around La Grande Pile was vegetated by open Betula–Pinus forest during this period but the occurrence of some pollen of Quercus and Corylus and a continuous Picea curve have also been reported for the same interval (Woillard, 1978; Beaulieu and Reille, 1992). Another time of birch-pine forest at around 40,000 14C yr, known as the Charbon Interstadial (Beaulieu and Reille, 1992), shows a similar radiocarbon age as the second Picea Interstadial. The Charbon Interstadial was again characterised by open Betula–Pinus forest and a continuous presence of Picea (Beaulieu and Reille, 1992). Finally, the Grand Bois Interstadial, dated at 29,000– 30,000 14C yr (Woillard and Mook, 1982), had open Pinus–Betula forest vegetation without a significant presence of Picea (Beaulieu and Reille, 1992). It was most likely slightly colder in comparison to the Pile and Charbon Interstadials, similar to the situation at Gossau.

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The high-resolution record of Lago Grande di Monticchio, southern Italy, is probably the most detailed continental record of environmental change in Europe during the last 100,000 yr (Zolitschka and Negendank, 1996; Allen et al., 1999, 2000). Some, but not all, of the climatic fluctuations during the Middle Wurmian . recorded at Monticchio are represented in the Gossau-Interstadial-Complex (Fig. 3). The correlation of the first Picea Interstadial at Gossau with the Monticchio records remains tentative due to insufficient age control. From the available data a correlation with pollen assemblage zone (PAZ) 13 is most reasonable. In southern Italy, this phase (PAZ 13) reflects a time of significant forest development but the presence of Gramineae and Artemisia pollen also indicates open woodland conditions (Allen and Huntley, 2000). According to dating, PZ 2 at Gossau is probably an equivalent of PAZ 11 at Monticchio and the second Picea Interstadial correlates with PAZ 9. Vegetation in southern Italy during this time was of open woodlandtype with Betula, Quercus, Ulmus and Fagus (Allen and Huntley, 2000). As in Gossau (PZ7), the last welldeveloped interstadial before the full glacial stage is dated between 32,000 and 29,000 yr BP.

6. Conclusions Luminescence dating of the delta sediments at Gossau allows a correlation with the first stadial period of the Late Pleistocene that corresponds to MIS 5d. Within a maximum of a few thousand years, the interglacial forest of the Eemian was replaced by tundra vegetation (Welten, 1981). Sedimentological evidence indicates the presence of glaciers at the northern border of the Alps at that time. During the Early Wurmian . interstadials, a more moderate climate allowed reforestation by boreal trees (Picea abies, Pinus). The first two interstadials were interrupted by a cold episode, probably during MIS 5b, with similar mean annual temperatures as during MIS 5d but lower precipitation (Welten, 1981; Guiot et al., 1989; Wegmuller, . 1992). Rapid changes in environmental conditions occurred throughout the Middle Wurmian. . There is evidence for two intervals with open woodland vegetation and a mean July temperature of about 13 C. In northern central Europe tree growth was restricted by climatic conditions at the same time indicating an increased latitudinal environmental gradient in Europe during the Late Pleistocene (Zagwijn, 1992). A reasonable explanation for a colder and probably dryer climate in the north is a southward shift of the polar front as interpreted from LGM ice-flow directions in the Swiss Alps (Florineth and Schluchter, . 2000). From the available data, a correlation of the Middle Wurmian . interstadials from Gossau with single Dansgaard–Oescherger (D/O)

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events remains speculative due to the lack of precise dating. However, evidence from the Gossau site indicates a series of significant environmental changes during MIS 3 that are difficult to explain by orbital forcing only. Acknowledgements Luminescence dating was carried out using the facilities at the Geologisches Institut, Universit.at zu . Koln, Germany. We thank W. Boenigk and collaborators for their kind help and hospitality. Irradiation was made at the Universite! Catholique de Louvain, Belgium, and we acknowledge the help by R. Debuyst and R. Dolhen. M. Vandergoes and M. Kelly helped by improving the English. The manuscript highly benefited from the comments of two anonymous reviewers. This study has been financially supported by the Swiss Nationalfonds (Grant-No. 21-063988.00). References Aitken, M.J., 1998. An Introduction to Optical Dating. University Press, Oxford, 267 pp. Allen, J.R.M., Huntley, B., 2000. Weichselian palynological records from southern Europe: correlation and chronology. Quaternary International 73/74, 111–125. Allen, J.R.M., Brandt, U., Brauer, A., Hubberten, H., Huntley, B., Keller, J., Kraml, M., Mackensen, A., Mingram, J., Negendank, J.F.W., Nowaczyk, N.R., Oberh.ansli, H., Watts, W.A., Wulf, S., Zolitschka, B., 1999. Evidence of rapid last glacial environmental fluctuations from southern Europe. Nature 400, 740–743. Allen, J.R.M., Watts, W.A., Huntley, B., 2000. Weichselian palynostratigraphy, palaeovegetation and palaeoenvironment; the record from Lago Grande di Monticchio, southern Italy. Quaternary International 73/74, 91–110. Balescu, S., Lamothe, M., 1992. The blue emission of K-feldspar coarse grains and its potential for overcoming TL age underestimates. Quaternary Science Reviews 11, 45–51. Bassinot, F.C., Labeyrie, L.D., Vincent, E., Quidelleur, X., Shackelton, N.J., Lancelot, Y., 1994. The astronomical theory of climate and the age of the Brunhes-Matuyama magnetic reversal. Earth and Planetary Science Letters 126, 91–108. Beaulieu, J.L.de, Reille, M., 1989. The transition from temperate phases to stadials in the long upper Pleistocene sequence from Les Echets (France). Palaeogeography, Palaeoclimatology, Palaeoecology 72, 147–159. Beaulieu, J.-L., de Reille, M., 1992. The last climatic cycle at La Grand Pile (Vosges: France): a new pollen profile. Quaternary Science Reviews 11, 431–438. Behre, K.E., Lade, U., 1986. Eine Folge von Eem und 4 WeichselInterstadialen in Oerel/Niedersachsen und ihr Vegetationsverlauf. Eiszeitalter und Gegenwart 36, 11–36. Behre, K.E., van der Plicht, J., 1992. Towards an absolute chronology for the last glacial period in Europe: radiocarbon dates from Oerel, Northern Germany. Vegetation History and Archeobotany 1, 111–117. Burga, C.A., Perret, R., 1998. Vegetation und Klima der Schweiz seit dem jungeren . Eiszeitalter. Ott Verlag, Thun. Caspers, G., Freund, H., 2001. Vegetation and climate in the Early Pleni-Weichselian in northern central Europe. Journal of Quaternary Science 16, 31–48.

Chaline, J., Jerz, H., 1984. Arbeitsergebnisse der Subkommission fur . Europ.aische Quart.arstratigraphie. Eiszeitalter und Gegenwart 35, 185–206. Dansgaard, W., Johnsen, S.J., Clausen, H.B., Dahl-Jensen, D., Gundestrup, N.S., Hammer, C.U., Hvidberg, C.S., Steffensen, . J.P., Sweinbjornsdottir, A.E., Jouzel, J., Bond, G., 1993. Evidence of general instability of past climate from a 250-kyr ice-core record. Nature 364, 218–220. Drescher-Schneider, R., 2000. Die Vegetations- und Klimaentwicklung im Riss/Wurm-Interglazial . und im Fruh. und Mittelwurm . in der Umgebung von Mondsee. Ergebnisse der Pollenanalytischen Untersuchungen. In: Husen van, D. (Ed.). Klimaentwicklung im Riss/Wurm . Interglazial (Eem) und Fruhw . urm . (Sauerstoffisotopenstufe 6-3) in den Ostalpen, 39-92. Mitteilungen der Kommision fur . . Quart.arforschung der Osterreichischen Akademie der Wissenschaften 12, Wien. Erfurt, G., Krbetschek, M.R., Bortolot, V.J., Preusser, F., 2003. A fully automated multi-spectral radioluminescence reader system for geochronometry and dosimetry. Nuclear Instruments and Methods in Physics Research B, in press. Florineth, D., Schluchter, . Ch., 2000. Alpine evidence for atmospheric circulation patterns in Europe during the Last Glacial Maximum. Quaternary Research 54, 295–308. Follieri, M., Giardini, M., Magri, D., Sadori, L., 1998. Palynostratigraphy of the last glacial period in the volcanic region of central Italy. Quaternary International 47/48, 3–20. Fuller, I.C., Wintle, A.G., Duller, G.A.T., 1994. Test of partial bleach methodology as applied to the infrared stimulated luminescence of an alluvial sediment from the Danube. Quaternary Science Reviews 13, 539–543. Geyh, M.A., Schreiner, A., 1984. 14C-Datierungen an Knochen- und StoXzahn-Fragmenten aus wurmeiszeitlichen . Ablagerungen im westlichen Rheingletschergebiet (Baden-W.urttemberg). Eiszeitalter und Gegenwart 34, 155–161. Geyh, M.A., Schluchter, . Ch., 1998. Calibration of the 14C time scale beyond 22,000 BP. Radiocarbon 40, 475–482. Geyh, M.A., Hennig, G., Oetzen, D., 1997. U/Th-Datierung interglazialer und interstadialer Niedermoortorfe und Lignite. Schriftenreihe der Deutschen Geologischen Gesellschaft 4, 187–200. Godfrey-Smith, D.I., Huntley, D.J., Chen, W.-H., 1988. Optical dating studies of quartz and feldspar sediment extracts. Quaternary Science Reviews 7, 373–380. . . . urm . Gruger, E., 1979. Sp.atriX, RiX/Wurm und Fruhw am Samerberg in Oberbayern—ein vegetationsgeschichtlicher Beitrag zur Gliederung des Jungpleistoz.ans. Geologica Bavarica 80, 5–64. Guiot, J., Pons, A., de Beaulieu, J.-L., Reille, M., 1989. A 140,000-year continental climate reconstruction from two European pollen record. Nature 338, 309–313. Huijzer, A.S., Vandenberghe, J., 1998. Climatic reconstruction of the Weichselian Pleniglacial in northwestern and central Europe. Journal of Quaternary Science 13, 391–417. Ivy-Ochs, S., 1996. The dating of rock surfaces using in situ produced 10 Be, 26Al and 36Cl, with examples from Antarctica and the Swiss Alps. Diss. ETH Zurich . No., 11763, pp. 135–141. Jerz, H., Mangeldorf, J., 1989. Die interglazialen Kalksinterablager. ungen bei Hurlach nordlich Landsberg am Lech. Eiszeitalter und Gegenwart 39, 29–32. Johnsen, S.J., Clausen, H.B., Dansgaard, W., Fuhrer, K., Gundenstrup, N., Hammer, C.U., Iversen, P., Jouzel, J., Stauffer, B., Steffensen, J.P., 1992. Irregular glacial interstadials records in a new Greenland ice core. Nature 359, 311–313. Jost-Stauffer, M., 2001. Fossil coleoptera (beetles) as indicators for climate and environment in Quaternary sediments of Switzerland. Unpubl. Ph.D. thesis, Universit.at Bern, 69 pp. Jost-Stauffer, M., Coope, G.R., Schluchter, . Ch., 2001. A coleopteran fauna from the middle Wurm . (Weichselian) of Switzerland and its

ARTICLE IN PRESS F. Preusser et al. / Quaternary Science Reviews 22 (2003) 1435–1445 bearing on palaeobiography, palaeoclimate and palaeoecology. Journal of Quaternary Science 16, 257–268. Kasse, C., Bohncke, S.J.P., Nadenberghe, J., 1995. Fluvial periglacial environments, climate and vegetation during the Middle Weichselian in the northern Netherlands with special reference to the Hengelo Interstadial. Mededelingen Rijks Geologische Dienst 52, 387–414. Keller, O., Krayss, E., 1998. Datenlage und Modell einer Rhein-LinthVorlandvergletscherung zwischen Eem-Interglazial und Hochwurm. . GeoArchaeoRhein 2, 121–138. Klaus, W., 1987. Das Mondsee-Profil: R/W-Interglazial und vier Wurm-Interstadiale . in einer geschlossenen Schichtenfolge. In: Husen van, D. (ed.), Das Gebiet des Traungletschers, Ober. osterreich. Eine Typregion des Wurm-Glazials, . 3-18. Mitteilungen . der Kommision fur . Quart.arforschung der Osterreichischen Akademia der Wissenschaften 7, Wien. . Krbetschek, M.R., Gotze, J., Dietrich, A., Trautmann, T., 1997. Spectral information from minerals relevant for luminescence dating. Radiation Measurements 27, 695–748. Kuttel, . M., 1989. Jungpleistoz.an-Stratigraphie in der Zentralschweiz. In: Rose, J., Schluchter, . C. (Eds.), Quaternary Type Sections— Imagination or Reality? Balkema, Rotterdam, pp. 179–191. Mejdahl, V., 1988. Long-term stability of the TL signal in alkali feldspars. Quaternary Science Reviews 7, 357–360. Muller, . U., 2001. Die Vegetations- und Klimageschichte im jungeren . Quart.ar anhand ausgew.ahlter Profile aus dem sudwestdeutschen . Alpenvorland. Tubinger . Geowissenschaftliche Arbeiten D7, 1–118. Murton, J.B., French, H.M., Lamothe, M., 1997. Late Wisconsinan erosion and eolian deposition, Summer Island area, Pleistocene Mackenzie Delta, N.W.T: Optical dating and implications for glacial chronology. Canadian Journal of Earth Sciences 34, 190–199. Ponel, P., 1995. Rissian, Eemian and Wurmian . coleoptera assemblages from La Grande Pile (Vosges, France). Palaeogeography, Palaeoclimatology, Palaeoecology 114, 1–41. Preusser, F., 1999a. Luminescence dating of fluvial sediments and overbank deposits from Gossau, Switzerland: fine grain dating. Quaternary Geochronology (Quaternary Science Reviews) 18, 217–222. Preusser, F., 1999b. Lumineszenzdatierung fluviatiler Sedimente— . Fallbeispiele aus der Schweiz und Norddeutschland. Kolner Forum fur . Geologie und Pal.aontologie 3, 1–62. Preusser, F., 1999c. Bleaching characteristics of some optically stimulated luminescence signals. Ancient TL 17, 11–14. Preusser, F., Kasper, H.U., 2001. Comparison of dose rate determination using high resolution gamma spectrometry and inductively coupled plasma—mass spectrometry. Ancient TL 19, 19–23. Preusser, F., Muller, . B.U., Schluchter, . C., 2001. Luminescence dating of sediments from the Luthern Valley, Central Switzerland, and implications for the chronology of the last glacial cycle. Quaternary Research 55, 215–222. Schluchter, . Ch., 1989. The most complete Quaternary record of the Swiss Alpine Foreland. Palaeogeography, Palaeoclimatology, Palaeoecology 72, 141–146.

1445

Schluchter, . Ch., 1991. Fazies und Chronologie des letztzeitlichen Eisaufbaus im Alpenvorland der Schweiz. In: Frenzel, B. (Ed.), Klimageschichtliche Probleme der letzten 130 000 Jahre. Fischer, Stuttgart/New York, pp. 401–407. Schluchter, . Ch., 1992. Terrestrial Quaternary stratigraphy. Quaternary Science Reviews 11, 603–607. Schluchter, . Ch., Maisch, M., Suter, J., Fitze, P., Keller, W.A., Burga, C.A., Wynistorf, E., 1987. Das Schieferkohlenprofil von Gossau (Kanton Zurich) . und seine stratigraphische Stellung innerhalb der letzten Eiszeit. Vierteljahrsschrift der Naturforschenden Gesellschaft Zurich . 132, 135–174. . Ch., Mangini, A., 2002. Stalagmite from the Austrian Alps Spotl, reveals Dansgaard-Oeschger events during isotope stage 3: implications for the absolute chronology of Greenland ice cores. Earth and Planetary Science Letters 203, 507–518. Walkling, A., 1997. K.aferkundliche Untersuchungen an weichselzeitlichen Ablagerungen der Bohrung GroXTodshorn (Kr. Harburg; Niedersachsen). Schriftenreihe der Deutschen Geologischen Gesellschaft 4, 87–102. Wallinga, J., 2002. Optically stimulated luminescence dating of fluvial sediments: a review. Boreas 31, 303–322. . Wegmuller, S., 1992. Vegetationsgeschichtliche und stratigraphische . Untersuchungen an Schieferkohlen des nordlichen Alpenvorlandes. Denkschriften der Schweizer Akademie der Naturwissenschaften 102, 1–82. Wegmuller, . S., Preusser, F., Muller, . B.U., Schluchter, . Ch., 2002. Palynostratigraphische Untersuchungen und Lumineszenzdatierung des Profils Galgenmoos und Implikationen fur . die Chronologie des letzten Glazialzykluses in der Schweiz. Eclogae Geologicae Helvetiae 95, 115–126. Welten, M., 1981. Verdr.angung und Vernichtung der anspruchsvollen . Geholze am Beginn der letzten Eiszeit und die Korrelation der Fruhw . urm-Interstadiale . in Mittel- und Nordeuropa. Eiszeitalter und Gegenwart 31, 187–202. Welten, M., 1982. Pollenanalystische Untersuchungen im Jungeren . . Quart.ar des nordlichen Alpenvorlandes der Schweiz. Beitr.age zur Geologischen Karte der Schweiz N.F. 156, 174 pp. Welten, M., 1988. Neue pollenanalystische Ergebnisse uber . das . Jungere . Quart.ar des nordlichen Alpenvorlandes der Schweiz (Mittel- und Jungpleistoz.an). Beitr.age zur Geologischen Karte der Schweiz N.F. 162, 40 pp. Wintle, A.G., 1997. Luminescence dating: laboratory procedures and protocols. Radiation Measurements 27, 769–817. Woillard, G.M., 1978. Grande Pile peat bog: A continuous pollen record for the last 140,000 years. Quaternary Research 9, 1–21. Woillard, G.M., Mook, W.G., 1982. Carbon-14 dates at Grand Pile: correlation of land and sea chronologies. Science 215, 159–161. Zagwijn, W., 1992. The beginning of the ice age in Europe and its major subdivisions. Quaternary Science Reviews 11, 583–591. Zolitschka, B., Negendank, J.F.W., 1996. Sedimentology, dating and palaeoclimatic interpretation of a 76.3 ka record from Lago Grande di Monticchio, Southern Italy. Quaternary Science Reviews 15, 101–112.