Vegetation and climate during warmer intervals in the Late Pleistocene of western and central Europe

Quaternary International, Vols 3/4, pp. 574i7, 1989.

1040-6182/89 $0.00 + .50 ~) 1990 INQUA/PergamonPress plc

Printed in Great Britain. All rights reserved.

V E G E T A T I O N AND CLIMATE DURING W A R M E R INTERVALS IN THE LATE PLEISTOCENE OF W E S T E R N AND C E N T R A L E U R O P E W a l d o H. Z a g w i j n

Geological Survey of The Netherlands, Postbox 157, 2000 AD Haarlem, The Netherlands

Many warmer intervals occurred during the last interglacial-glacial cycle (130-10 ka) in Europe. The vegetational record shows several types of such intervals, among which the forest periods of the Eemian interglacial and the Amersfoort-Brorup interstadials of the Early Weichselian are of special interest. A series of map reconstructions is used to present some of the relevant vegetational and palcoclimatic characterizations. They represent two types of temperate intervals occurring in the Late Pleistocene in Europe, one with a rather uniform distribution of vegetation types, a warmer oceanic climate, and a high sealevel. The other type shows strong vegetation gradients (both north-south and east-west), a more continental climate, and a relatively low sea-level. Inland-ice probably persisted in the far north during this last type of interval. It is suggested that these two types of 'interglacial' occurred throughout the Pleistocene.

part of the last interglacial-glacial cycle is treated in some detail.

INTRODUCTION In the last interglacial-glacial cycle of western Europe, several types of warmer interval can be recognized in pollen diagrams (de Jong, 1988). As early as 1928, Jessen and Milthers defined an interglacial as an interval of time with a vegetational and hence climatic evolution similar to that of the Holocene including a clear expansion of thermophilous trees. On the other hand, in their view, interstadials do not show a clear expansion of thermophilous trees. As West (1984) pointed out, in nature, clear cut distinctions between interglacials and interstadials may be absent, because climate and vegetation may vary from one area to another during the same period. Moreover, any interval with a relatively warmer climate during cold periods may be called an interstadial, even if it was not a period of forest growth. This paper deals first with the Eemian and Early Weichselian succession and then briefly with that of the Middle and Late Weichselian; lastly, the paleogeography of the vegetation and climate during the early

Eemian

Betula

Pinus

EEMIAN AND EARLY WEICHSELIAN (WURMIAN) The Eemian interglacial shows a very characteristic succession in the dominance of broad-leaved trees (Fig. 1). This succession is fairly uniform over a large part of western and central Europe. The Early Weichselian saw several warmer and colder phases during the period following the Eemian interglacial. The actual number of warmer episodes and their correlation between one area and another has been the subject of considerable discussion. For an updated review of these problems and their solutions, the reader is referred to Behre (1989). Usually, these warmer intervals, which in the area under discussion were periods with a dominantly forest vegetation, are referred to as interstadials. An example from The Netherlands is presented in Fig. 2. According to the definition of Jessen and Milthers (1928), the warmer intervals of the Early Weichselian in several areas such

Tilia Quercus UlmusVFraxinusV Alnus Corylus

Picea Abies Taxus vCarpinus v

i

0

100%

FIG. 1. Schematic pollen diagram of the Eemian interglacial in The Netherlands (from de Jong, 1988).

57

58

W.H. Zagwijn

b. Late Weichselian

a. Middle Weichselian Artemisia

RUIGE KLUFT

Chenopo-

Betula • diaceae

Artemisia

HUKERMEER

Pinus

Betula

Salix

= E

LEGEND ]trees (EE~Iherbs i

0

c.

Middle Weichselian

HENGELO

l 0

[]

i

100=/o 15 15 15°/o

Betula

Artemisia

0

100%

75%

40°1o

heather

50% 20 10%

d. Early Weichselian AMERSFOORT

Betula

Pinus

Picea

Alnus

t 100%

30 10%

0

100%

55%

55%

55%

i

6~0%

FIG. 2a-d. Pollen diagrams for different types of warmer interval in The Netherlands (a and c: Hengelo Interstadial of the Middle Weichselian; h: BOiling-Aller0d Interstadials of the Late Glacial; d: Br0rup Interstadial found in boring Amersfoort 3 (Early Weichselian); according to de Jong, 1988).

as NW Germany, Poland, and The Netherlands, are interstadial in character. Further to the south, in NE and E France, however, several warmer episodes of post-Eemian age show a much more demanding forest vegetation and climate, and might therefore be considered to be interglacial in character. All authors now agree that these warmer intervals in the south (called St. Germain 1 and 2) are correlative with the Amersfoort-Br0rup and Odderade interstadials farther north (Fig. 3). Evidently the warmer intervals of the Early Weichselian were accompanied by much greater vegetational and climatic variability in western Europe than had been the case during the preceding Eemian interglacial. This problem will be discussed in some detail below, but one particular point may be dealt with here. Behre (1989) underscores the occurrence of two main interstadials, the Br0rup and the Odderade, which are separated by a period of open vegetation and strong cooling. In NW Germany the first of these two interstadials was divided into two parts by a period of cooling. In The Netherlands, however, three warmer intervals separated by phases with open vegetation can be distinguished, and these are called Amersfoort, Bnarup, and Odderade. Of these three, BrOrup is clearly characterized by a Picea zone in which Picea omorikoides is strongly developed. This facilitates good correlation with sections in NW Germany and Denmark (Fig. 3). There is no difference of opinion about the conclusion that Amersfoort and Br0rup (sensu stricto) of The Netherlands are equivalent to Br0rup (sensu lato) of NW Germany and Denmark. The cold interval between Amersfoort and Brorup,

i.e. pollen zone EW III of The Netherlands, may be discussed here in some detail. In the Amersfoort region the two interstadials, called Amersfoort and Br0rup (sensu stricto) and showing forest vegetation, are clearly separated by a period of open vegetation. Moreover, the peat beds of the two interstadials are separated by a layer of eolian sand (cover sand), and cryoturbatic structures also occur between the two peat beds (Zagwijn and Paepe, 1968). These phenomena indicate that a true cold phase separated the two interstadials in this region. Farther eastward, as exemplified by the Wardhausen boring along the DutchGerman border (van de Meene and Zagwijn, 1978), the two interstadials lie within a single peat bed, though a zone with high herbaceous pollen percentages still separates the two interstadials. Farther to the northeast, in NW Germany, separate peat beds are not found either, and there a zone with higher values of herb pollen is only weakly developed and the two separate interstadials of The Netherlands merge into one, called Brorup (sensu lato; Behre, 1989). Still farther eastward, the two main interstadials (Br0rup and Odderade) can also be recognized in eastern Germany (Erd, 1973) and Poland (Tobolski, 1986; Mamakowa, 1986; Jastrz~;bska-Mame~ka, 1985). In some of these localities the lower interstadial of the two is still subdivided by a phase of cooling like that in NW Germany, but in central Poland such a subdivision cannot be seen (Zgierz-Rudunki, Warszawa-Wola). There, the lower interstadial shows only a long Betula phase followed by a Pinus phase. In western Europe, south of The Netherlands, in all sites investigated so far, the lower interstadial is

59

Vegetation and Climate in the Late Pleistocene

NORTHERN GERMANY 10 ° 20°C July

EASTERN FRANCE

THE NETHERLANDS

Estimated timescale (Ka) 70-

10° 20" C July

l

1

Odderade EW Vl EW V -~ Br~rup

EW IV

O

EW III

100-

EW I 110-

Eemian

E5

Melisey 2 Saint Germain 1

1C

Saalian

5;

Brorup

1B 1A

Amersfoort

uJ

Melisey 1

\

\ Eemian

Eemian

E4 E3 E2 E1

/

Rudunki

Odderade

E6

120

130

(

Saint Germain 2

Amersfoort EW II

/

10 ° 20°C July

Middle Weichselian Ognon _ _

90-

CENTRAL POLAND

Eemian

) Riss(ian)

/

j

Saalian

/

Saalian

FIG. 3. Climate and stratigraphy of Eemian to Early Weichselian (Wiirmian) in western and central Europe.

tripartite: a cool phase separating a lower from an upper temperate phase. In eastern France (Woillard, 1978, 1979; de Beaulieu and Reille, 1984a,b; Gremmen et al., 1984) the cool phase is a pine-birch phase separating two phases of deciduous forest, and in the Alps a pine-dominated zone separates two Piceadominated phases (Welten, 1982; Wegmiiller, 1985; Griiger, 1979; Klaus, 1987). Unlike the pattern found in The Netherlands, forest was not replaced by open vegetation during this stage of cooling.

MIDDLE AND LATE WEICHSELIAN(W[IRMIAN) In the Middle Weichselian, open tundra-like conditions prevailed in The Netherlands. During some intervals there were slightly warmer conditions as indicated by a moderate expansion of shrubs (such as Betula nana), an increase of warmth-loving tall steppic herbs such as Artemisia, Chenopodiaceae, and Thalictrurn, an increase of aquatic plants, or combinations of these features (Fig. 2). No signs of reafforestation were seen in any of these cases. Three such warmer phases have been recognized so far in The Netherlands (i.e. Moershoofd, Hengelo, and Denekamp, dated around 50,000-42,000, 39,000-37,000 and 32,000-30,000 years BP respectively). The following authors have dealt with the vegetation succession during this interval in the region of The Netherlands: van der Hammen et al. (1967), van der Hammen and Wijmstra (1971), Koistrup (1980), Kolstrup and Wijmstra (1977), van der Meer et al. (1984), and Zagwijn (1974).

Further north, too, similar phases of temporary climatic improvement have been demonstrated (Behre, 1989). There, the earliest occurrence (called Oerel Interstadial) is dominated by heathers (e.g. Calluna and Empetrum), but later, as in The Netherlands, these became less important. Along a north-south gradient the Middle Weichselian period shows a transition from tundra conditions in the north to steppic conditions farther south. This is especially clear in the diagrams of La Grande Pile and Les Echets (Woillard, 1978, 1979; de Beaulieu and Reille, 1984a,b), showing an increase of Artemisia, Chenopodiaceae, and other steppic elements, probably indicating warmer and much drier conditions in the south. A number of interstadials, characterized by an increase of Juniperus, Betula, and partly of Pinus, are indicated. In particular with respect to age, those found in La Grande Pile are comparable to those found in The Netherlands in the Middle Weichselian (Woillard and Mook, 1982). Finally, another type of warmer phase occurred in the Late Weichselian, the Aller~d interstadial type (Fig. 2). Not only Aller~d but also the preceding B~lling period is often considered to be an interstadial of its own. Aller~d is characterized by an expansion of birch and pine forest of the subarctic and high boreal types. Thermophilous trees are absent in most of western and central Europe. Toward the south, especially in the Alpine area, these interstadials are not well expressed in the lowlands but can be recognized in upland situations.

60

W.H. Zagwijn

Their duration was short, of the order of 500 to 1000 years, which is a lower order of magnitude than the duration of the Early Weichselian interstadials.

PALEOGEOGRAPHIC MAPS (VEGETATION AND CLIMATE)

Vegetational and paleoclimatic conditions of the Eemian and part of the Early Weichselian in western and central Europe will be compared on the basis of a set of map reconstructions. The two maps pertaining to the Eemian (Fig. 4a, b) have been taken from Gerasimov and Velichko (1982) with some adaptations and simplifications. The reconstructions for parts of the Early Weichselian (Figs 6-9) are new. The locations used can be found in Fig. 5, i.e. Amersfoort boring 3 (Zagwijn, 1961), Moershoofd (Zagwijn, 1961), Wanssum (Zagwijn, 1961), La Grande Pile (Woillard, 1975, 1978, 1979) Wardhausen (van de Meene and Zagwijn, 1978), Les Echets (de Beaulieu and Reille, 1984a,b), R. l'Amourette (Gremmen et al., 1984), Oerel (Behre and Lade, 1986), Odderade (Averdieck, 1967), Rehderstall (Menke and Tynni, 1984), Br0rup (Andersen, 1961), Kittlitz (Erd, 1973), Wl'adysl'awow/ Turek (Tobolski, 1986), Zgierz-Radunki (Jastrz~bskaMame~ka, 1985), Warszawa-Wola (Mamakowa, 1986), Mutten Signau I, Sulzberg, Diirnten (Welten, 1982), Gondiswil (Wegmiiller, 1985), Samerberg (Griiger, 1979), and Mondsee (Klaus, 1987). The map does not show the site of Val Bourget (Gremmen, 1982), north of Grenoble (France), where a vegetation development comparable to that of other Alpine sites has been recorded. This site was used in the construction of the western limit of the mountain region vegetation. The vegetation maps show pollen-analytic data obtained from pollen diagrams of the localities in question. For each zone, one representative pollen sample was selected per location and the percentages of some important pollen types were calculated from the original publication. Because the number of localities is still small, only generalized isopollen lines could be drawn. Due to the great differences between areas, however, a rather interesting picture evolved. Conversion of the pollen data to estimated mean temperatures of the warmest month (July) in °C is based on the following assumptions: (1) The northern forest line is approximately represented by herb values of 50% when the tree pollen is mainly Betula and Pinus. This line coincides with the 10°C July isotherm. (2) The transition from Betula forest to pine-dominated forest runs roughly parallel to the July isotherm of 12°C. (3) The presence of Quercus is indicated by pollen values higher than 2%. Estimated July temperature is above 13°C. (4) The presence of Ainus glutinosa is indicated by

pollen values above 4%. Estimated July temperature lies above 14°C. (5) High values of Quercus, Ulmus, Tilia, and Carpinus and the presence of Buxus have been taken to represent mean July temperatures of 18°C and higher. During the climatic optimum of the Eemian interglacial, i.e. pollen zone E5 in The Netherlands (Fig. 4a), broad-leaved forests dominated by Carpinus (hornbeam) spread over a large part of western and central Europe. The climate was oceanic, the sea had invaded many coastal lowlands, and the sea-level was high. The forest succession during the Eemian interglacial was remarkably uniform over large parts of the continent, the gradient being very gradual. This facilitates easy correlation over a large area. According to Velichko (in Gerasimov and Velichko, 1982), summer temperatures were slightly higher than at present, especially in the extreme north, although the pattern was similar to the one prevailing at present over western and central Europe, and gradients were flat. According to the same author, however, winter temperatures were distinctly higher than they are now, especially in the north and northeast. Permafrost did not occur, not even in the northernmost part of the continent. On the whole, air masses from the ocean during the Eemian moved farther east over the continent than they reach today. During the first cold stadial of the Early Weichselian (pollen zone EW Ia of The Netherlands), the pollen data indicate deforestation over the entire area considered in this paper. However, because pollen values for trees, mainly birch and pine, are generally substantial, there was probably a park landscape in the north and a forest steppe in the south. This means that in July temperatures were probably about 10°C over a large area and slightly higher toward the south. In The Netherlands and NW Germany, there was an area rich in heathland, particularly Calluna heath. This probably indicates an oceanic influence. It is not yet possible to construct isotherms on the basis of these data, but gradients were probably very flat over a large area. During the warmer Amersfoort interstadial (pollen zone EW IIb of The Netherlands) and its timeequivalent to the east and to the south, conditions were very different from those prevailing during the Eemian interglacial (Fig. 5a). There were strong north-south gradients in the vegetation, particularly in the western part of the continent, but a west-east gradient was also present. In the southwest, broad-leaved forest developed and some broad-leaved trees extended their area farther to the north. This feature, already discussed above, is clearly expressed on the map. In the Alps mountain forest dominated, whereas farther north pine-birch and birch forest was dominant. During this period the sea-level was relatively low: the southern part of the North Sea floor was not flooded above 40 m below the present sea-level, which, if we correct for subsidence, means a sea-level slightly lower than 20 m below the present sea-level.

Vegetation and Climate in the Late Pleistocene

61

Eemian (Carpinus - zone E 5 ) Carpinus-Quercus forest

idem. with Picea

Picea-Quercus forest with Betula ~

Picea-Abiesmountain forest

steppe-forest

~

Okm

E e m i a n ( C a r p i n u s - z o n e ) July isolherrns (°C)

(b)

o

-"

_

~

¢80

~-~

I

18 °

~

~:~ O ~ ~

i0

50kin I

FIG. 4. Vegetation and climate during the Eemian of Europe. (a) Vegetation map of the Eemian; (b) Estimated isotherms in °C during July for the Eemian (adapted from Gerasimov and Velichko, 1982).

62

W.H. Zagwijn

!

,

•3 14

e15 • 12

14

%

r

%

0

/

1 Amersfoort 2 Moershoofd 3 Wardhausen 4 Wanssum 5 La Grande Pile 6 Les Echets 7 R. de L'Amourette 8 Oerel 9-10 Rehderstall + Odderade 11 Br~rup 12 Kittlitz 13 WYadystaw6wnear Turek 14 Zgierz - Rudunki 15 Warszawa - Wola 16 Sulzberg 17 Mutten Signau I + Gondiswil 18 DOrnten 19 Samerberg 20 Mondsee ~,m~iSat°'o nWseichs elian

50kin

1

I

FIG. 5. Locations of Early Weichselian (Wtirmian) sites used in the preparation of the paleovcgetation and paleoclimatic maps shown in Figs 6--9.

Early Weichsellan

(EW I; Melisey

I) ............ isopollenline of Ericales(mainly Calluna)

"

-- ,, ----,-,~, ..~.z~. ........ i'".g ...... \ . , ,r'-.'~'-;~;-.'x:';~ - ,-~,tu"la-

witll patCh~s''~ \N NN.

pinuS

-.. x

40%

~

//1~---

isopollenline of herbs

forest

-50=/0

50%.'--'~. /

4o./.

less open

5o%

i !

c~,,,

50km I

~

FIG. 6. Vegetation during the first stadial of the Early Weichselian (pollen zone EW la).

63

Vegetation and Climate in the Late Pleistocene

Early Weichselian (EW lib; Amersfoort / St. Germain la) ,~"e-

isoplollenline of Betula

j,,~ a. 4 isopollenline of Quercus x

~ a r e a

with >50% Picea

::~ii~i area with >25% Quercus + @::"$*::::Ulmus + Tilia + Carpinus ~ ~ ~-'/Hu~ - OUlU/d

0 [

- ~ - 70°,,o

50km J

Early Weichselian (EW lib; Amersfoort / St. Germain la) mountain area

f 12°

0 I

estimated isoterm of mean temperature of warmest month(July)

50km I

FIG. 7. Vegetation (a) and climate (b) during the optimum of the Amersfoort interstadial (pollen zone EW IIb) and time equivalents.

64

W.H. Zagwijn

Early Weichselian (EW III Inter-Amersfoort-Bmrup-St. Germain Ib) (a)

'~

,~

~ a r e a

_r~

o

F

/

of Pinus-Picea

isopollenlineof Picea

/

/~--

isopollenlineof herbs

I

- isopollenlineof Betula

Pinus

50%,,,e.. ~

2

0

,o°,Y

-

~

Betula /

o

,(

,

50km !

Early Welchsellan (EW III; Inter-Amersfoort.Bmrup /St. Germain Ib) mountainarea

S

estimatedmean-temperatures of the warmestmonth(July)

12°

10"

12°

0 |

50km I

FIG. 8. Vegetation (a) and climate (b) during the Amersfoort-BrOrup cold spell (pollen zone EW llI) of The Netherlands and time equivalents.

Vegetation and Climate in the Late Pleistocene

65

Early Weichselian (EW IV(b); Brerup - St. Germain Ic)

f /.

- - isopollenlineof Picea / ..-- isopollenlineof Alnus

/

i

Piceadominant Quercus+ Ulmus + Tilia + Carpinus >25%

ominant(>t~uv/°) (>60%) clomlnan'

~i,~i/nus

0

~ ~

50kin 1

Early Weichselian (EW IV(b); Brerup - St. Germain Ic) f 14° ~

meantemperatureof month(July)

warmest

mountaina r e a

14 °

I

>12%C

14° 0

..........-.-....:.!:::.:.~::!i-::-:-.-:.!:i~:

,~

.

0 I

i

51~m i

F|G. 9. Vegetation (a) and climate (b) during the optimum of the Br~rup (sensu stricto) interstadial (pollen zone EW IVb) and time equivalents.

66

W.H. Zagwijn

If we convert these data to July isotherms, we find the following: high temperatures comparable to today's in the southwest, a warmer influence extending to the north, but not farther than The Netherlands. Towards the east, large areas were cool, around 11°C. In the Alps relatively cool conditions prevailed too, which promoted the growth of dominant Picea forest at lower altitudes. Two maps (Figs 8a, b) show the situation during the Amersfoort-Brtarup cold spell in The Netherlands (pollen zone EW III), which, as discussed above, is not recorded as occurring with such intensity farther eastward. In The Netherlands the vegetation opened up and permafrost even developed locally. In eastern France the deciduous forest disappeared, yielding to birch and pine forest. Toward the northeast, however, there was little change. In the Alps, Picea was largely replaced by Pinus. These changes are also reflected on the map showing the estimated July isotherm for this interval (Fig. 8b). In the west there was a dramatic change with the development of a cold influx extending from the northwest as far as southern France, but elsewhere there was little change. During the BrVrup (s.s.) interstadial (pollen zone EW IVb in The Netherlands), the distribution of the vegetation followed lines similar to those seen during the first warmer interval (Amersfoort). In the southwest there was oak-hornbeam forest again (Fig. 9a). Farther to the north some thermophilous trees reached The Netherlands, but also Picea, among which the relict species P. omorika was important. In the Alps Picea was dominant again, whereas Pinus dominated the plains of northern Germany and Poland. The sealevel was low, as it had been earlier, during the Amersfoort interstadial. The reconstructed pattern of the July isotherms (Fig. 9b) is very similar to that of the Amersfoort interstadial, although temperatures may generally have been slightly higher. The general picture of the two warmer interstadials under discussion is as follows. They were generally cooler than the Eemian interglacial, variations over the continent being greater. The climate was definitely more continental than in the Eemian over a large area, perhaps with the exception of the southwest. The biggest change in temperature during the intervening cold spell between Amersfoort and Br~rup was in the west. Evidently oceanic depressions could not penetrate deep into the continent, presumably because they were blocked by anticyclones in the east. It may be assumed that during the first cold after the Eemian, inland-ice built up to a certain extent in the northeast, and that this inland-ice persisted during the Amersfoort and Br~rup intervals. A role would also have been played by varying extension of the sea-ice off the Norwegian coast, particularly during the cold spell between Amersfoort and Br~rup (s.s.) when it may have moved southward. In this paper no reconstructions are presented for

the remaining stadial and interstadial (Odderade/St. Germain 2) intervals of the Early Weichselian. These intervals were similar in climatic pattern to those of the first cold stadial and the Amersfoort interstadial. This means that during the Early Weichselian, climatic conditions in Europe oscillated between two more or less stable conditions - - one cold, the other cooltemperate - - as reflected in the above-mentioned maps. The general conclusion is that two types of forested temperate interval of prolonged duration can be recognized in the Late Quaternary of Europe. One is of the Eemian type, characterized by a high sea-level, marine transgression into coastal lowlands, an oceanic climate similar to or warmer than the present one, with vegetation and climate uniform over large areas, which means that distinct pollen-stratigraphic correlations are possible. In this interval Abies penetrated far to the north (Fig. 10). During the temperate intervals of the Early Weichselian, to the contrary, the sea-level was relatively low, no evidence of transgression into coastal lowlands has been found, and the climate was cooler and more continental. Because there were distinct north-south and west-east gradients in vegetation zones and climate, pollen diagrams for different areas are not easy to correlate without additional data. During these intervals Abies did not reach farther than the Alpine region (Fig. 10). It is conceivable that the difference between this type of warmer interval and the

Norihem limits of Abies Distribution

o

j

. . . .

.~:::::

:......:

..:~.~ .:.~...~,.

.:.:.:...,.

.:

~iiiiii::~

-:~:~:!:~:~:~::::-

FIG. 10. Positionof the northern limitof Abies duringa numberof temperate climatic intervals in the Quaternary.

Vegetation and Climate in the Late Pleistocene

Eemian was related to persisting land-ice in the far northern part of the continent. Comparison of the Early Weichselian interstadials with the Eemian may thus provide a clue helping to explain differences observed between older warm temperate (interglacial) intervals of the Pleistocene. The present author has elaborated this point in more detail in another paper (Zagwijn, in press). For practical stratigraphic work this concept means that correlations between some interglacial deposits may be hampered by the possibility of large vegetational gradients from one area to another. REFERENCES Andersen, S.Th. (1961). Vegetation and its environment in Denmark in the Early Weichselian glacial (Last Glacial). Danmarks Geologiske Undersegelse, R II 75, 1-175. Averdieck, F.-R. (1967). Die Vegetationsentwicklung des EemInterglazials und der Friihwiirm-Interstadiale von Odderade/ Schleswig-Holstein. Fundamenta, B2, 101-125. Beaulieu, J.-L. de and Reille, M. (1984a). The pollen sequence of Les Echets (France): a new element for the chronology of the Upper Pleistocene. Gdographie Physique et Quaternaire, 38, 3-9. Beaulieu, J.-L. de and Reille, M. (1984b). A long Upper Pleistocene pollen record from Les Echets, near Lyon, France. Boreas, 13, 111-132. Behre, K.-E. (1989). Biostratigraphy of the Last Glacial period in Europe. Quaternary Science Reviews, 8, 25--44. Behre, K.-E. and Lade, U. (1986). Eine Folge yon Eem und 4 Weichsel-Interstadialen in Oerel/Niedersachsen und ihr Vegetationsablauf. Eiszeitalter und Gegenwart, 36, 11-36. Erd, K. (1973). Pollenanalytische Gliederung des Pleistoz~ins der Deutschen Demokratischen Republik. Zeitschrift geologischer Wissenschaften, 9, 1087-1103. Gerasimov, I.P. and Velichko, A.A. (1982). Paleogeography of Europe during the Last One Hundred Thousand Years (Atlasmonograph). In Russian with English summary. Nauka, Moscow, 154 pp. Gremmen, W.H. (1982). Palynological investigations of Late Pleistocene deposits in Southeastern France. Thesis, University of Groningen, 94 pp. Gremmen, W., Hannss, C. and Puiss6gur, J.J. (1984). Die warmzeitlichen Ablagerungen am R au de I'Amourette (tri~ves, franz6sische Alpen). Eiszeitalter und Gegenwart, 34, 87-103. Griiger, E. (1979). Sp~itrisz, Risz/Wtirm und Friihwiirm am Samerberg in Oberbayern - - ein vegetationsgeschichtlicher Beitrag zur Gliederung des Jungpleistoz~ins. Geologica Bavarica, 80,5--64. Hammen, T. van der, Maarleveid, G. C., Vogel, J.C. and Zagwijn, W.H. (1967). Stratigraphy, climatic succession and radiocarbon dating of the Late Glacial in The Netherlands. Geologie en Mijnbouw, 46 (3), 79-95. Hammen, T. van der and Wijmstra, T.A. (1971). The Upper Quaternary of the Dinkel valley. Mededelingen Rijks Geologische Dienst, N.S. 22, 55-214. Jastrz~bska-Mamefka, M. (1985). Interglacjal Eemski i wczesny Vistulian w Zgierzu-Rudunkach na Wyzynie L6dzkiej. Acta Geographica Lodziensia, 53, 1-75. Jessen, K. and Milthers, V. (1928). Stratigraphical and palaeontological studies of interglacial freshwater deposits in Jutland and north-west Germany. Danmarks Geologiske Undersegelse, II rke, 48.

67

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