Ž .Global and Planetary Change 31 2001 407–425www.elsevier.comrlocatergloplacha

Extent and age of the Last Glacial Maximum in the southeasternsector of the Scandinavian Ice Sheet

Juha Pekka Lunkkaa,), Matti Saarnistoa, Valeri Geyb, Igor Demidovc,Vera Kiselovab

a Geological SurÕey of Finland, PO Box 96, FIN-02151 Espoo, Finlandb Geological Expedition, 24r1 OdoeÕsky Street, 199155 St. Petersburg, Russia

c Institute of Geology, Karelian Research Centre, Pushkinskaya 11, 185610 PetrozaÕodsk, Russia

Received 25 January 2000; accepted 23 May 2001

Abstract

Ž 14 .Lithostratigraphical methods combined with absolute dating OSL and C were used to establish the Late PleistoceneŽ .stratigraphy and the Last Glacial Maximum LGM limit of the Scandinavian Ice Sheet south and east of the Lake Onega

Basin. An estimate of the ice growth rate for the southeastern sector of the ice sheet, from western Finland to the LGM limitin the northeast Russian Plain is also presented. In addition, an interpretation of palaeoenvironments that existed during theLGM in the Vologda and adjacent areas is also discussed.

Evidence from boreholes and exposures indicate that the Scandinavian Ice Sheet entered the Vologda and southernŽ .Arkhangelsk area, only once during the last cold stage, during the Late Valdai Weichsel . It is also concluded that the

Scandinavian Ice Sheet reached its maximum at ca. 18 000 calendar years ago in the Vologda area and its extent was morerestricted than previously thought. The timing of the LGM at 18 ka presented here, combined with recent ice growth resultsfrom Finland, suggest that the southeastern sector of the Scandinavian Ice Sheet expanded across Finland to its maximumposition in the northern Russian Plain in 7000 calendar years.q2001 Elsevier Science B.V. All rights reserved.

Keywords: Scandinavian Ice Sheet; Last Glacial Maximum; Lake Valdai; OSL; NW Russian Plain; Russia

1. Introduction

The Eurasian ice sheets have traditionally beendivided into the Kara–Barents Ice Sheets and theScandinavian Ice Sheet. The interplay between theseice sheets in space and time during the Valdai

) Corresponding author. Fax:q358-205-5012.Ž .E-mail addresses: juhapekka.lunkka@gsf.fi J.P. Lunkka ,

Ž .matti.saarnisto@gsf.fi M. Saarnisto .

Ž .Weichsel cold stage has provoked much contro-versy during past decades. It has recently been shown

Ž .by Svendsen et al. 1999 and references therein thatthe extent, timing and dynamics of the Kara andBarents Ice Sheets during the Valdai were different

Ž .than that presented in Grosswald’s 1980, 1998model. Recent results on glacial cover over vastareas of Eurasia suggest that Grosswald’s modeloverestimates the size of the ice cover at the Last

Ž .Glacial Maximum LGM by more than a halfŽ .Svendsen et al., 1999 .

0921-8181r01r$ - see front matterq2001 Elsevier Science B.V. All rights reserved.Ž .PII: S0921-8181 01 00132-1

( )J.P. Lunkka et al.rGlobal and Planetary Change 31 2001 407–425408

Relatively few studies have recently focused onthe extent and timing of the southeastern sector ofthe Scandinavian Ice Sheet during the last glacial

Žcycle i.e. from the southeastern part of Fennoscan-dia to southeast and east of the Onega Basin; see Fig..1 . The advance rate, chronology of ice growth and

decay patterns are still waiting to be fully addressed,

although the LGM limit for the Scandinavian IceSheet north of this area was recently presented by

Ž .Larsen et al. 1999 .Stratigraphy of the last interglacialrglacial cycle

and the extent of the Scandinavian Ice Sheet in thenortheast Russian Plain during the Valdai has previ-ously been studied mainly by Russian workers. The

Ž . Ž .Fig. 1. The study area southeast of Lake Onega, the main exposures black dots , towns squares , lake basins and river valleys. ExposuresŽ . Ž . Ž . Ž . Ž . Ž .discussed in this paper are: 1 Kirillov sections, 2 Shadrina section, 3 Puchka II section, 4 Jouma section, 5 Vaga section and 6

Ž . Ž .Njandoma sections. Black line indicates the Valdai glacial maximum according to Krasnov et al. 1971 and Krasnov 1971 .

( )J.P. Lunkka et al.rGlobal and Planetary Change 31 2001 407–425 409

results are summarised in English in several papers,Ž .e.g. by Faustova 1984, 1995 , Velichko and Faus-

Ž . Ž .tova 1986 , Sudakova and Faustova 1995 , Faus-Ž . Ž .tova and Gribchenko 1995 , Grosswald 1980, 1998

Ž .and Velichko et al. 1997 among others. At present,it seems to be fairly well established that during theValdai cold stage an ice sheet from northern Scandi-navia entered the northwestern part of the RussianPlain only once, during the Late Valdai. However,some workers have suggested that ice covered partof the north Russian Plain already during the Early

Ž .or Middle Valdai see Arslanov et al., 1981 . It hasrecently been shown that the Kara and Barents IceSheets in Arctic Russia were most extensive during

Žeither the Early or the Middle Valdai Mangerud et.al., 1999 , but the extent of the Scandinavian Ice

Sheet during the Early and Middle Valdai is stillunknown. There is lithostratigraphical evidence thatthe Scandinavian ice sheet covered southern Finland

Žduring this time Saarnisto and Salonen, 1995;.Bouchard et al., 1990; Hirvas et al., 1995 , but

perhaps its margin did not reach very far beyond theBaltic Basin and Russian Karelia. However, there isstill no evidence that indicates the actual limit andtiming of the EarlyrMiddle Valdai ice extent insoutheastern Scandinavia.

Knowledge on the extent of the Scandinavian IceŽ .Sheet in its southeastern sector Fig. 1 during the

Late Valdai is largely based on geomorphologicalinterpretations and borehole data. Prominent ice-marginal landforms that run across the northwesternRussian Plain have been used for the LGM recon-structions, which has led to different interpretationsof the LGM limit. In the present study area forexample, 37 different LGM limits have been sug-

Ž .gested see Gey and Malakhovskiye, 1998 . Never-theless, various ice extent reconstructions for theLGM limit summarised, for example, by Krasnov et

Ž . Ž .al. 1971 , Grosswald 1980, 1998 , Denton andŽ . Ž .Hughes 1981 , Velichko et al. 1984, 1997 and

Ž .Gey and Malakhovskiye 1998 differ only slightlyfrom each other in a large scale. However, the timewhen the Scandinavian Ice Sheet reached its maxi-mum is still poorly defined.

In this paper, an attempt is made to establish astratigraphical scheme for the study area, define theextent of the Scandinavian Ice Sheet and the age ofLGM in the southeastern part of the Onega Basin

Ž .Fig. 1 . In addition to that, palaeoenvironments thatexisted in the area during the last glacial cycle andthe growth and decay rates of the Scandinavian IceSheet during the late Middle and Late Valdai arealso briefly discussed. Deposits from the MoscowŽ . Ž .Saale glaciation and the Mikulino Eemian inter-glacial are also briefly discussed when encountered

2. Study area

The study area is situated in the northwestern partŽ .of the Russian Plain Fig. 1 . The general relief of

the landscape in the area is primarily dictated bygently, southeastwards dipping sediment strata rang-ing from Devonian to Triassic in age. Towards the

Ž .northwest, the Precambrian Baltic FennoscandianShield forms the bedrock, while southeast of LakeOnega Paleo- to Mesozoic sedimentary rocks occuras sandstones, shales and limestones. Quaternarysediments form relatively thick accumulations, espe-cially where numerous end-moraine systems occur.These deposits are often several tens of metres thick.

A large part of the study area is situated morethan 150 m above the present sea level and thehighest points reach well over 200 m a.s.l. The majorlakes in the area occupy tectonically formed

Ž .Graben-type basins. White Lake 113 m a.s.l. andŽ .Lake Kubenskoye 110 m a.s.l. belong to the River

ŽVolga drainage basin, while Lake Vozhe 120 m. Ž .a.s.l. and Lake Lacha 117 m a.s.l. drain into the

White Sea via the River Onega. Other lowland areaslike the River Vaga valley and the River Suhonavalley lie well below 150 m a.s.l. and presently drainnorth into the North Dvina drainage basin.

3. Methods

Methods used in this work include conventionalsedimentological techniques combined with absolutedating methods. In various parts of the study area,natural exposures in gravel pits and along riverbankswere investigated, using the modified facies and

Ž .architectural element analysis of Miall 1978, 1984 .Lithofacies logging was carried out to define thelateral extent and vertical variation of sedimentaryunits within each section, to obtain information on

( )J.P. Lunkka et al.rGlobal and Planetary Change 31 2001 407–425410

the sedimentary environments. Clast fabric measure-ments on suitable diamictons were carried out whenpossible to provide information on the genesis of thediamicton and to indicate the ice movement direc-

Žtion. The a-axis a-axes 2–6-cm long anda:b axes.ratio )3r2 orientation and dip of 25 clasts were

measured from a 20=20-cm area. The data wasrecorded and resultant vector calculated with eigen-

Ž .values. Structural measurements dip directions fromfault planes and hinge lines of folds were made onglaciotectonised structures beneath diamicton unitsin order to define local shear stresses caused by theglacial overriding. In addition, the orientation ofcurrent-induced structures in sorted sediments wasmeasured to reveal flow directions during deposition.Results of clast fabric, palaeocurrent and structural

Ž .data is presented as single arrows resultant vectorsin Fig. 5.

Ž14 .Samples for absolute dating C and OSL wereŽcollected from the sediment exposures Tables 1 and

.2 . Organic bulk samples were dated in the Radiocar-bon Laboratory of the Geological Survey of Finland.The alkali-insoluble fraction was used for dating,after an acid–alkali–acid pre-treatment. The datingtechnique involved proportional counting of CO2

and the application of pulse-shaped discrimination as¨Ž .described by Mantynen et al. 1987 and Aikaa et al.¨ ¨¨

Ž .1992 . OSL samples were taken mainly fromglaciofluvial, fluvial and aeolian sand and analysedin the Nordic Laboratory of Luminescence Dating atRisø, Denmark. Sample preparation, dosimetry andequivalent dose measurements followed the proce-

Ž .dures outlined e.g. in Larsen et al. 1999 . Samplesfor microfossil analyses were also collected andanalysed from suitable sediments. In addition, someborehole data collected in connection with an exten-sive Quaternary mapping programme between 1960sand 1980s, in which the authors Gey and Kiselovaparticipated, are also presented here. This data in-cluding pollen and14C-dates was used for strati-graphical purposes. However, especially in the east-ern part of the study area, natural exposures and

borehole data is sparse and therefore geomorphologi-cal field observations was the main method for deter-mining the LGM limit in that area.

4. Results

4.1. Borehole data

Stratigraphy and the maximum extent of the Scan-dinavian Ice Sheet for the study area were deter-mined using extensive borehole data that was origi-nally cored for mapping purposes. The results of atotal amount of 26 cores were investigated in orderto obtain a stratigraphical framework for the south-ern part of the study area. The locations and sedi-ment succession of individual cores are presented inFigs. 2 and 3.

Lithostratigraphical observations indicate that incores N9a, N14, N23 and N10 the uppermost till unitis underlain by sorted sediments, mainly silt, clay,sand with a subordinate amount of peat and gyttja

Ž .horizons see Fig. 3 . In cores N14 and N10, thesecond till unit occurs beneath sorted sediments men-tioned above. In rest of the cores, the uppermostsedimentary units are composed of silt, clay, sandwith peat and gyttja that often occur upon a till unitŽcores N5, N6, N4, N16, N20, N18, N15, N13, N22,

.N2 in Fig. 3 .In most of the cores shown here, pollen work was

carried out from organic and clastic, fine-grainedsediments. The most representative pollen sequences

Ž .from the cores are presented in Gey et al. 2001 .Ž .According to pollen evidence in Gey et al. 2001 ,

the pollen spectra in cores N9a, N20a, N20, N19 andN21 show great similarities to that of the Mikulino

Ž .type-site cf. Grichuk, 1984 . On the other hand,pollen spectra in cores N1, N4, N7 and N8 indicatethe Early and Late Valdai successions.

A total amount of 1214C dates have been ob-tained from the organic horizons in the core material

Ž . Ž .Fig. 2. Borehole sites black dots with numbers and cross-sections lines with letters discussed in this paper. The extent of theScandinavian Ice Sheet at the LGM according to the new data is also indicated. The reconstruction of the LGM is based onlithostratigraphical observations, borehole material, biostratigraphy and absolute dating results. The list of14C- and OSL results is presentedin Tables 1 and 2.

( )J.P. Lunkka et al.rGlobal and Planetary Change 31 2001 407–425 411

( )J.P. Lunkka et al.rGlobal and Planetary Change 31 2001 407–425412

Fig. 3. Lithostratigraphical borehole logs and the stratigraphical interpretation of sedimentary units for the southern part of the study area.Numbers above the logs refer to the sites in Fig. 2.

Ž . 14Fig. 3 and Table 1 . C ages range from an infiniteŽ .age of over 55 830 BP borehole N16 to 29 380"

Ž . 14370 BP borehole N8 . C dates obtained merely

indicate the minimum ages of the sediments in ques-tion. Although the organic material dated could havealso been reworked from older deposits, thick gyttja

( )J.P. Lunkka et al.rGlobal and Planetary Change 31 2001 407–425 413

Table 1List of C-14 agesSamples are taken from boreholes and sections indicated in thetext and figures. Laboratory numbers are also indicated.

Ž .Locality no. Laboratory no. Age BP

N1 LU-94 )41000N3 LU-1944 34360"400N4 LU-2064 43560"1050N5 LU-1959 )44600N6 LU-2065 )43550N7 LU-2537 )48930N8 LU-2446 29380"370N9 LU-2539 49850"2100N10 LU-2415 44450"2170N11 LU-2445 )46840N15 LU-1834 52570"1270N16 LU-1783 )55830N17 LU-1950 )55400Jouma Su-3055 45000"1400Jouma Su-3056 54000q4400ry2800Jouma Su-3057 43200"1300Puchka II Su-3058 55500q5600ry3300Puchka II Su-3059 52400q5300ry3200Shadrina Su-3060 47500"1800Vaga Su-3061 35200"1200Njandoma Su-3062 52400q4300ry2800

and peat horizons, for example in cores N4, N17,N15 are thought to be in situ deposits.

ŽLithostratigraphical and biostratigraphical for.biostratigraphy see Gey et al., 2001 evidence as

well as14C dates suggest that the grey till unit at theŽbase of several cores e.g. N5, N6, N16, N20, N18,

.N15, N13, N22, N2, N10, N14 in Fig. 3 was laiddown prior to the Mikulino interglacial. This till isthought to represent the Moscow Till. The upper,brownish till in cores N9a, N10, N23 and N14represents a till unit that deposited during the LateValdai. Sorted sediments in between these two tillsrepresent Mikulino and Early to Late Valdai sedi-ments.

Seven cross-sections were reconstructed from thebore hole data in order to reveal the general stratigra-phy of the area from Lake Kubenskoye to Lake

Ž . XLacha see Figs. 2 and 4 . In cross-section A–AŽ .Fig. 4 , a separate till unit overlies sorted sedimentsandror an older till unit in the Kubenskoye Basin.However, further to the east and to the west of theKubenskoye Basin, an older till is the topmost till

Ž X.unit see Fig. 4; cross-section A–A . The other six

cross-sections in Fig. 4 show the general stratigraphyfor the area and indicate that three separate till unitsexist in the area.

4.2. Logged sections

4.2.1. KirilloÕ sectionsIn the Kirillov area, gravel and sand deposits,

mainly sandurs and sandur deltas form a huge icemarginal complex, which is situated very close to or

Žat the Last Glacial Maximum limit cf. Gey and.Malakhovskiye, 1998 . A composite log shown in

Fig. 5 was constructed from these pits to indicateproximal to distal variation of this sandur delta com-plex. In the proximal side, the material logged isvery coarse and represents channel-fill and bar ele-ments. Palaeoflow indicators suggest that the domi-nant current direction was from the northeast andeast. Two superimposed till units overlie these barand channel-fill elements. The till units are inter-preted here as basal tills and large-scale glaciotec-tonic structures beneath the till indicate an ice-flow

Ž .direction from the north Fig. 5 . Laminated andsyndepositionally deformed silt and clay overlie thetill unit and the top part of this aeolian unit alsoshow cryoturbation. Two OSL samples were takenfrom the proximal side of the sandur delta. An age of210"20 ka was obtained from a subaquatic channel

Ž .fill element beneath the lower till unit see Fig. 5 .An OSL date from aeolian silt above the till unitsyield an age of 16.4"1.5 ka.

A 4-m-thick section was logged in the distal partof the sandur delta complex. The lower part of thesection is characterised by planar cross-bedded graveland trough and planar cross-bedded sand while theupper part is composed of massive, horizontally andripple-bedded fine sand. Trough and planar cross-be-dded units in the lower part of the section areinterpreted here as glaciofluvial in origin and sand inthe upper part of the section as an aeolian cover. TheOSL sample from the glaciofluvial material yield anage 19.3"1.3 ka while the age of the aeolian cover

Ž .is 17.6"1.2 ka see Fig. 5 .According to the data presented here, the till units

occur in the proximal part of the sandur delta. Thisindicates that the ice-front oscillated in the proximalpart of the marginal complex and deposited two tillunits. However, the till units are absent in the distal

( )J.P. Lunkka et al.rGlobal and Planetary Change 31 2001 407–425414

( )J.P. Lunkka et al.rGlobal and Planetary Change 31 2001 407–425 415

Fig. 4. Cross-sections based on unpublished Russian borehole data and their stratigraphical interpretations. For locations of thecross-sections, see Fig. 2.

part of the area where sorted sediments of glacioflu-vial origin were deposited beyond the ice margin. Itis suggested here that these till units represent theLate Valdai tills and the glaciofluvial material in thedistal part of the area deposited at the same timebeyond the ice-front.

4.2.2. Shadrina sectionŽ .In the exposure at Shadrina Figs. 2 and 5 , two

till units are interbedded with sorted sediments. Thebasal diamicton is interpreted here as the MoscowTill whereas the topmost till unit represents till thatwas laid down by ice during the Late Valdai from

Ž .the north 3508 . The ice-flow direction was deter-mined measuring glaciotectonic structures immedi-ately beneath the uppermost till. Organic-rich silt andclay overlies the basal till unit.14C-date obtainedfrom the organic matter yielded an age of 47 500"

Ž .1800 BP Su-3060 . However, it is not known if

these organic-rich layers were deposited during aninterglacial or weather they represent interstadial orreworked material. The organic-rich layers pass withan erosional contact into 1-m thick, fine to medium

Ž .sand parallel-bedded . The upper part of the unit issyndepositionally deformed and overlain with a sharpcontact by 2.5-m-thick unit of laminated silt andsand with abundant dropstones. This rhythmite andlaminated silt and fine sand unit grades graduallyinto a 2.5-m thick, glaciotectonically deformed sand,rhytmite and diamicton unit beneath the uppermostValdai Till. It seems evident that rhythmites andsand and a stratified diamicton mixture were de-posited into a glaciolacustrine basin. One sand hori-zon in the glaciotectonized unit gave an OSL age45"5 ka. It is assumed that the OSL age does not,however, represent the true age of the subglaciallydeformed sand since the sample showed an internal

Ž .evidence of incomplete bleaching see Fig. 5 .

( )J.P. Lunkka et al.rGlobal and Planetary Change 31 2001 407–425416

Fig. 5. Sediment logs of the main exposures investigated and discussed in text. Ice flow directions are derived from both glaciotectonicstructures and clast fabrics. For locations, see Fig. 1.

4.3. Puchka II section

Three separate till units are present in the Puchkasection. Two till units at the basal part of the sectionare interbedded with stratified gravel and ripple-be-dded sand and grade into organic-rich silt and claywith shell fragments. The second till unit from thebase is overlain with an erosional contact by almosta 2-m-thick gravel and sand. The basal part of this

unit consists of relatively coarse and stratified pebblygravel, which is overlain by planar cross-beddedsand. Laterally, this unit continues at least few tensof metres in the section. At the logging site, graveland sand represent channel deposits, most likely alongitudinal bar. A 5-m-thick till unit rests at the topof the section and its basal contact is erosional.Within this till, there are several sand horizons thatoccur as layers or lenses. Clast fabric measurements

( )J.P. Lunkka et al.rGlobal and Planetary Change 31 2001 407–425 417

carried out from the middle part of the till indicateŽ .ice-flow from the north 108 . Two conventional

14C-dates from the organic silt and clay unit andfrom a peat clast in the stratified pebbly gravel unit

Ž .both yield ages of more than 50 ka BP Fig. 5 . AnOSL date from sand beneath the topmost till yieldsan age of 46"4 ka while the OSL date from a sandlayer within the topmost till yields an age of 38"5ka. These OSL ages are most likely from an unsuit-able sand material and not bleached as also indicatedin Table 2.

Based on the dates and sedimentological observa-tions, it seems plausible that two till units at the baseof the section were deposited prior to the Late Valdaipossibly during the penultimate glaciation. Lacus-trine sediments between these two tills are thought tobe pre-Mikulino since the pollen evidence at fourlevels of this unit indicate open steppe and openbirch forest vegetation. It is also suggested thatduring the Middle Valdai substage, river sedimentswere laid down and finally the ice from the northdeposited the topmost till in the Late Valdai.

4.4. Jouma section

The section near the village of Voskrechenskayadisplays only one till unit at the base of the sectionŽ .Fig. 5 . Two terrestrial, organic layers occur abovethe till at the base of the section. These organic

layers are separated by pedochemically zoned andmotled siltrsilty sand that contains organic matter.This unit passes into laminated, organic-rich silt thatbecomes coarser upwards. This lacustrine unit isoverlain by stratified pebble to granule gravel thatfine upwards into planar cross-bedded and ripple-be-dded as well as parallel-bedded sand and finally intosyndepositionally deformed silt and sand. The unitrepresents channel-fill and overbank deposit. The toppart of the section is composed of an upward finingcycle of laminated and syndepositionally deformedsilty sand, silt and clay with subordinate amount of

Žorganic material and shell fragments mainlyBithy-.nia tentaculata . The section is covered by ca. 1.5-

m-thick layer of aeolian sandy silt and silt.Three14C-ages from different levels of the section

Ž . Žwere carried out Fig. 5 . Wood fragments mainly.Pinus sylÕestris from the first organic horizon upon

the basal till yield an age of 54 000q4400ry2800Ž .BP Su-3056 and organic matter from the second

Žpeat horizon yield an age of 45 000"1400 BP Su-.3055 . An age obtained from the organic layer, 3 m

Žfrom the ground surface is 43 200"1300 BP Su-.3057 . The OSL results from the top 1.5 m gave ages

of 17.2"1.6 and 16.0"1.3 ka while overbank de-posits upon the channel fill sands gave an age of158"18 ka.

It is suggested here that the till at the base of thesection was deposited during the Moscow stage. The

Table 2Ž .List of luminescence OSL datings with one standard deviation

Samples 983205, -06 and-09 show internal evidence of incomplete bleaching.

Lab code Sample code Site Dated material Age Dose Dose rateŽ . Ž . Ž .ka Gy Gyrka

983201 LGMTL1 Kirillov aeolian sand 16.4"1.5 31"2 0.192983202 LGMTL2 Kirillov galciofluvial sand 210"20 308"24 0.147983203 LGMTL3 Kirillov aeolian sand 17.6"1.2 25.9"0.5 0.148983204 LGMTL4 Kirillov glaciofluvial sand 19.3"1.3 27.8"0.5 0.144

Ž .983205 LGMTL5 Puchka fluvial sand ? 46"4 66"5 0.144983206 LGMTL6 Puchka glaciofluvial sand 39"5 55"6 0.121983207 LGMTL7 Jouma fluvial sand and silt 153"18 231"23 0.150983208 LGMTL8 Jouma aeolian sand 17.5"2.0 79"6 0.257983209 LGMTL11 Shadrina glaciofluvial sand 45"5 92"8 0.168983210 LGMTL12 Jouma aeolian sand 15.7"1.6 79"6 0.274

Ž .983211 LGMTL13 Vaga glaciofluvial sand ? 220"30 217"30 0.111983212 LGMTL14 Vaga aeolian sand 14.8"1.2 17.3"0.8 0.116983213 LGMTL15 Njandoma glaciofluvial sand 39"3 81"5 0.118983214 LGMTL16 Njandoma glaciolacustrine silt 148"17 210"19 0.150

( )J.P. Lunkka et al.rGlobal and Planetary Change 31 2001 407–425418

organic horizons overlying the Moscow Till couldrepresent a late phase of Mikulino interglacial or theEarly Weichselian interstadial while top cover sand,according to OSL dates, must have deposited duringthe Late Valdai. Although the OSL age for overbankdeposits yield an age of 158 ka, the interpretationmentioned above seems the most probable one.

4.4.1. Vaga sectionPleistocene sediments in this laterally extensive

Ž .ca. 200 m exposure overlie the Permian sandstone.The glaciotectonically deformed Permian sandstoneis overlain by a till unit that passes into deformed

Ž .and parallel-bedded sand and silt Fig. 5 . An OSLage from deformed sand above the till unit gave anage of 220"20 ka. Upon this unit, parallel-beddedsand occurs with an erosional lower contact. Thisgrades into laminated silt and clay that containsorganic fragments. The14C age of the organic mate-rial from the middle part of the laminated unit is

Ž . Ž35 200"1200 BP Su-3061 . A cobble gravel bed a.lag horizon overlies the laminated unit. The lower

contact of the lag horizon is erosional and representsa major hiatus in the section. A sand-dominated bedrests on the lag horizon. Several ice-wedge casts arepresent in this sand bed. Massive silt and clay, ca.2-m thick, above sand passes finally into cover sandat the top of the section. An OSL date from the sandunit within ice-wedge casts yield an age of 14.8"1.2ka.

Till at the base of the section is interpreted here asthe Moscow Till. Glaciotectonic structures beneaththe till indicate that the ice movement was from thewest during this stage. The syndepositionally de-formed sand and silt bed that overlies the till repre-sents most likely glaciofluvial outwash. Parallel-be-dded sand and silt that grades into laminated silt andclay represent a lacustrine facies and according to14 Ž .C date of 35 200"1200 BP Su-3061 , it wasdeposited during the Middle Valdai. However, theage does not necessarily indicate the age of thelacustrine facies since organic fragments could repre-sent reworked material from older sediments. Theprominent lag horizon in the sequence may representa major hiatus as noted above, while sand withice-wedge casts above this horizon indicate severeclimatic conditions at 15 ka. Fine sediments abovethe cryoturbated sand unit suggests a short-lived

lacustrine conditions, which were followed by thedeposition of aeolian cover sand.

4.4.2. Njandoma sectionsThe area between the Vaga River valley and

Njandoma is characterised by outwash plains and agently undulating landscape. In the Njandoma area,

Ž .two sections were investigated see Figs. 1 and 5 .Glaciotectonized pebble gravel and sand occurs atthe base of the eastern section. Above this gravel andsand unit, two till units are present. The colour of thelower till is grey while the upper till is brown. Thrustplane measurements in the glaciotectonized unit indi-cate that the ice movement was from the northwest.

A diamicton unit occurs at the base of the westernŽ .section see Fig. 5 . However, it was not possible to

investigate the nature of this unit because of the poorexposure. Upon this diamicton, a 5-cm-thick peatwas observed. Laminated silt containing organicseams rests on the peat layer. A14C-age of theorganic-rich lamina at the top of the laminated unit is

Ž .52 400q4300ry2800 BP Su-3602 . The lami-nated silt bed passes into 30-cm-thick, parallel andripple-bedded sand. An OSL sample taken from thetop of this sand bed yields an age of 39"3 ka. Twotill units, similar to those at the top of the easternexposure, occur with an erosional lower contactabove the sand bed.

The basal part of the Njandoma section is difficultto interpret. Damicton at the base of the westernsection most likely represents the pre-Valdai till.Peat and lacustrine silt may represent sediments thatwere laid down during the Mikulino stage and theEarly to Middle Valdai substages. An OSL age of39"3 ka from sand beneath the till units show thatthe till units were deposited during the Late Valdai.

5. General stratigraphy and the LGM limit in thesouthern part of the study area

Based on the results presented above, it waspossible to establish a general stratigraphical schemefor the southern part of the study area. Litho- andbiostratigraphical results combined with dating re-sults indicate that two separate till units occur in theKubenskoye–White Lake area while there is onlyone till unit in the southern part of the study area

( )J.P. Lunkka et al.rGlobal and Planetary Change 31 2001 407–425 419

Ž .see Figs. 2 and 3 . Since there are interglacial peatand gyttja horizons above a till unit at the base ofseveral boreholes and investigated sections fromnorth of Lake Kubenskoye to south of the Ry-bisnkoye Reservoir, the lower till unit is thought torepresent the Moscow till. Similarly, till above inter-glacial or sorted sediments of the Early to MiddleValdai age in boreholes N14, N23, N10, N9a and incross-sections A–AX and B–BX as well as in theKirillov, Shadrina, Puchka II sections represents atill bed that was laid down during the Late Valdai.Following this stratigraphical argumentation and alsotaking into account glacial geomorphology of thearea, the extent of the Late Valdai glaciation can bedrawn as shown in Fig. 2.

The absolute dating of the LGM limit is based on14C and OSL ages obtained from suitable boreholematerial and organic horizons as well as sand unitsfrom exposures studied. A total amount of 20 radio-carbon dates relevant for determining the LGM hasbeen performed from various stratigraphical horizonsin the Lake Kubenskoye area and their age range

Ž .from 21 410"150 BP LU-18B up to over 55 830Ž . 14BP LU-1783 . Most of the C-dates are not useful

for a direct dating of the LGM limit. This is becausethere are very few14C-dates available in suitablestratigraphical positions. Therefore, the dates merelyindicate the minimum ages of the sediments in ques-tion. However, the radiocarbon dates obtained be-neath the Valdai till can potentially give the maxi-mum age for the LGM limit.

Ž .Arslanov et al. 1970 reported an age of 21 410Ž ."150 BP i.e. 25 ka cal BP from a peat layer that

occurred beneath the Valdai till in the River Puchka.Other dates presented here from organic materialbeneath the Valdai Till yield ages more than 40 ka

Ž .BP see Fig. 3 . So far, previously published ageŽ .from the Puchka I section Arslanov et al., 1970

indicate that the Scandinavian Ice Sheet entered theŽ 14area after 25 ka cal BP for calibration of C-ages

.see Kitagawa and van der Plicht, 1998a,b .A total amount of 10 OSL samples was taken

from sections in the southern part of the study area.Four samples from a gravel pit at Kirillov, two fromthe Puchka II section, three from the Jouma section

Žand one from the Shadrina section see Figs. 1 and 5.and Table 2 . As discussed above, gravel and sand

deposits at Kirillov form a huge ice-marginal com-

plex that situated very close to or at the LGM limitŽ .see Fig. 2 . The OSL results from aeolian silt abovethe Valdai Till in the proximal part of the sandurdelta yield an age of 16.4"1.5 ka. An age of210"20 ka was obtained from the proximal part ofthe sandur delta in a subaquatic channel fill that issituated stratigraphically beneath the bipartite Valdaitill succession. The other two OSL samples at Kir-illov were taken from aeolian cover sand in the distalpart of the sandur delta and also beneath this aeoliansand in the glaciofluvial cross-ripple-bedded sandunit. The results from the aeolian sand unit yield anage of 17.6"1.2 ka and the glaciofluvial sand be-

Ž .neath 19.3"1.3 ka see Fig. 5 . The glaciofluvialsand unit is thought to represent glacial outwashderived from the ice margin as it stood at the LGMposition.

Based on the results presented here and alsoconsidering the suitability of the OSL material dated,it can be concluded that three of the OSL agesranging from 16.4 to 19.3 ka are in accordance withthe general lithostratigraphy of the area. Therefore,the age of the LGM falls in between the age of thedistal sandur delta sands, namely 19.3"1.3 ka andthe overlying aeolian sand dated at 17.6"1.2 ka forthis area. The age obtained from medium sand in thechannel facies of the sandur delta appears to be tooold at least one order of magnitude. This is becausethere is relatively good evidence that the sandur deltacomplexes at Kirillov and west of the KubenskoyeBasin must have been laid down at the ice-margin atthe time of the Last Glacial Maximum. However, ifthis is not the case, the channel fill and parts ofsandur deltas beneath the Valdai Till in this arearepresent deposits that were laid down prior to orduring the Moscow glaciation.

The OSL samples taken from the Shadrina sectionand also the samples at Puchka II that are associatedwith the Valdai Till gave ages 45"5, 46"4 and

Ž .39"5 ka see Fig. 5 and Table 2 . These threesamples, however, show internal evidence of incom-plete bleaching and therefore do perhaps not indicatethe age of the sand units sampled. Three OSL sam-ples from the Jouma section located outside theLGM limit were taken from the top three m of the

Ž .section see Fig. 5 . Two OSL ages from aeoliancover sand at the top of the section gave Late Valdaiages comparable to those at the top of the Kirillov

( )J.P. Lunkka et al.rGlobal and Planetary Change 31 2001 407–425420

sections. The age of the lowest OSL sample atJouma indicates that the overbank deposits above thefluvial channel sand and gravel were deposited dur-ing the Late Moscow. This age seems to be problem-atic if two organic horizons were indeed depositedduring the Mikulino or the Early Valdai as suggestedabove.

The age of the LGM in the southern part of thestudy area relies directly on two OSL ages obtainedfrom the Kirillov area. These ages show that aglacier deposited distal glaciofluvial sand at 19.3"

1.3 ka outside its margin while the eaolian sand unitat Kirillov and also at Jouma to the south wasdeposited 17.6"1.2 and 17.2"2 ka ago. Thesedates together with stratigraphical observations fromthe boreholes and exposures serve as best age-esti-mates of the LGM for the southern part of the studyarea.

6. General stratigraphy and the age of the LGMlimit in the eastern part of the study area

Seven cross-sections have been reconstructed fromthe borehole data and the stratigraphical interpreta-tion of these cross-sections for the area from LakeKubenskoye northwards to Lake Lacha is shown inFig. 4. In addition, four exposures were investigatedand geomorphological studies in the field were car-ried out to define the extent of the last glaciation.

Cross-section A–AX in Fig. 4 indicates that an icelobe occupied the Kubenskoye Basin during themaximum stage of the Valdai glaciation as also

Ž .noted by Arslanov et al. 1970 . However, further tothe east and to the west of the Kubenskoye Basin,

ŽMoscow till is the topmost till unit see Fig. 4;X.cross-section A–A . The other six cross-sections

shown in Fig. 4 reveal the general lithostratigraphyof the area where at most three separate glacial till

Ž .units Pre-Moscow, Moscow and Valdai tills wererecognised. In all of the cross-sections, except incross-section D–DX, the Valdai till is present indicat-ing that the Scandinavian Ice Sheet did overrun thestudy area. However, in sections along the VagaRiver and in exposures between towns Vologda andVelsk the Valdai till is absent.

Geomorphological observations combined withthe borehole data suggest that the glacial relief of the

study area show clear geomorphological features thatare related to the last glaciation. These geomorpho-logical areas can be grouped into the following.

Ž .1 The ice-proximal zone where glacial erosionhas dominated and later post-glacial, lacustrine sedi-

Žments filled the basins for example, White Lake andKubenskoye–Vozhe–Lacha depression, see also

X X X .cross-sections E–E , F–F and G–G in Fig. 4 ,Ž .2 The end-moraine belts that form upland areas

Žand comprise glacigenic ridges for example, southof the White Lake, east of Kubenskoye, Vozhe andLacha basins and around Njandoma, see also cross-

X X X .sections B–B , C–C , D–D in Fig. 4Ž .3 The distal zone characterised by relatively

even topography, gently undulating ground surfaceŽwith distal outwash plains for example, the Kirillov

.area and the areas east of Njandoma .The Valdai till is not present in the southern part

of the River Vaga valley, south of Osinovskaya ca.Ž30 km north of the Vaga Section cf. Larsen et al.,

.1999 . Based on geomorphological observations andborehole data, it is suggested that the LGM limitsituated in the end-moraine belt in the Njandomaarea. Further south between the Kubenskoye Basinand the Njandoma area, the LGM limit can be placedbetween the end-moraine and outwash plain zones asindicated in Fig. 6.

The age of the LGM is difficult to determine forthe eastern part of the study area. An OSL date from

Ž .a silty sand unit beneath the uppermost i.e. Valdaitill, in the Njandoma area yield an age of 39"3 ka.A 14C age from organic material beneath silty sandyield an age of 52 400q4300ry2800 BP. Thesedates indicate that ice overrode the area and movedpossibly few tens of kilometres towards the east toits maximum position after 39"3 ka. On the otherhand, observations made in a section in the VagaRiver valley show the absence of the Valdai till inthat area. The absence of till post-dating a till bedthat was deposited during the Moscow glaciation inthis part of the Vaga valley shows that ice did notenter the area during the Valdai cold stage. Theice-wedge cast horizon that occur above thepebblercobble lag layer in the section was depositedsome 14.9"1.2 ka. However, further north, some

Ž .35–50 km along the Vaga River, Larsen et al. 1999described and dated the sediments in sections andconcluded that in this area maximum position of the

( )J.P. Lunkka et al.rGlobal and Planetary Change 31 2001 407–425 421

Fig. 6. Ice dammed lakes and their drainage directions, main sandur and sandur delta complexes, and the ice extent at the LGM. DistributionŽ .of lakes is modified after Kvasov 1979 . Dashed line indicates the previous estimate of the Valdai glaciation limit.

Scandinavian Ice Sheet was reached ca. 17 ka anddeglaciation could have started some 14.8 ka ago.The ice margin had already retreated to the SE

ŽOnega basin by 14.2 ka ago Saarnisto and Saarinen,.2001 .

7. Palaeoenvironmental interpretation

Palaeonvironments of the study area during thelast glacial cycle are briefly discussed here using the

data presented above. In addition, ancient shorelinealtitudes, delta levels and threshold elevations pre-

Ž .sented by Gey and Malakhovskiye 1998 have beenused to reconstruct the extent of palaeolakes andtheir drainage routes at the Last Glacial MaximumŽ .Fig. 6 .

It has to be stressed that in all of the sectionsstudied several hiatuses occur and therefore the sedi-ments reveal only certain and often very brief timeslices of the period between the Moscow and theLate Valdai glaciations. Nevertheless, an attempt is

( )J.P. Lunkka et al.rGlobal and Planetary Change 31 2001 407–425422

made to shed light on major events and changes inpalaeoenvironments in the study area.

Till deposited during the Moscow glaciation ap-pears as the oldest glacigenic unit in the sectionsinvestigated, although pre-Moscow tills have occa-sionally been encountered. The Moscow glaciationwas undoubtedly more extensive than the Valdaiglaciation and the ice sheet during the Moscowglaciation entered the southern part of the study areafrom between 3208 and 208, while the ice flow intothe eastern part came from the west.

Mikulino sediments in sections are represented bypeat in most of the boreholes and normally they reston the Moscow till. However, for example in bore-holes N21, N20 and N24 Mikulino sediments weredeposited in lacustrine environments at 100 to 115 mabove the present sea level.

Data for the Early and Middle Valdai palaeoenvi-ronmental reconstruction is very limited. Although itis evident, according to the borehole, terrace andpalynological data that lacustrine conditions per-sisted at least for some time in major depressions,like in the Prisukhonian and Mologa–Sheksnian de-pressions, and in the Vaga river valley, lake levels ofindividual basins probably did not exceed 120 ma.s.l. Above this altitude, fluvial sediments are com-mon. For example, at the Puchka II section, fluvialsediments dominate the sedimentary succession fromthe Middle Valdai time and the palaeocurrent mea-surements indicate water flow towards the KubeskoyeBasin.

Ž .Gey and Malakhovskiye 1998 recently discussedpalaeoenvironmental conditions during the LGM andpost-LGM time. They reported several terrace levelsalong major lake basins in the area that were formedat or just after the LGM. Previous observations onlake terraces and sandur delta levels, combined withthe borehole data shown in this paper, suggest thatrelatively extensive lakes were formed in front of theice just after the ice-retreat from the Kubenskoye

Ž .basin as also noted by Kvasov 1979 . The waterlevel of these lakes was at ca. 130 m a.s.l. and they

Ž .were connected via wide straits Fig. 6 . At theŽShadrina section, glaciolacustrine sediments includ-

.ing waterlain tills are well represented in the se-quence and occur immediately beneath the Late Val-dai till. This suggests that the ice-front oscillated andwas directly in contact with a glacial lake in the

Molaga–Sheksnian Basin. In the Vaga section atabout 100 m a.s.l., lacustrine or glaciolacustrinesediments may have been deposited at this level atthe time of the LGM. However, the lag horizon andcryoturbated sand units dated to 14.9"1.2 ka indi-cate that this lake dried out when the ice-frontreceded towards north and opened a drainage route

Ž .to the east see Fig. 6 .

8. Discussion

The position of the Scandinavian ice margin at theLGM in the northwestern Russian Plain has previ-ously been defined using mainly geomorphologi-

Ž .cal methods prominent end-moraine systems com-bined with stratigraphical evidence. As Gey and

Ž .Malakhovskiye 1998 have discussed, more than 30different LGM positions have been previously sug-gested for the area surrounding Lake Kubenskoye,White Lake, lakes Lacha and Vozhe, and the Ry-biskoye Reservoir. Comprehensive geological workcarried out between the 1960s and 1980s, the resultsof which are partially presented in this paper, indi-cate that ice did not reach the Rybinskoye Reservoirduring the Late Valdai. Instead, it occupied theWhite Lake and Kubenskoya depressions and the icefront had a lobate form in the marginal zone close tothese basins. East of the Kubeno–Vozhe–Lacha de-pression, the LGM limit is more difficult to define.However, according to evidence shown above, it isclear that the Scandinavian ice sheet did not enter theVaga river valley during the Valdaian stage. Wesuggest that the ice margin terminated in the Njan-doma area, at the prominent end moraine zone there.East of Njandoma, the landscape is gently undulatingand sandurs and sandur deltas dominate it. Furthersouth, between Njandoma and north of Lake Kuben-skoye, the LGM limit is defined using prominent endmoraine systems and outwash plains.

Dating of the LGM for the area covered by thesoutheastern part of the Scandinavian Ice Sheet haspreviously been based on14C-dates obtained fromorganic matter beneath the Valdai till, which bynecessity are older than LGM by unknown number

Ž .of years. As discussed above, Arslanov et al. 1970Ž .reported an age of 21 410"150 BP 25 ka cal BP

on organic matter beneath the Valdai till at the

( )J.P. Lunkka et al.rGlobal and Planetary Change 31 2001 407–425 423

Puchka I section, close to Lake Kubenskoye. Furthersouthwest, in the section of the Neman river near thevillage of Gozha in Belorussia, a14C-date of 18 730

Ž ."1230 BP ca. 22 cal BP was obtained fromorganic-rich lacustrine silt deposited prior to deposi-

Žtion of the Late Valdai till cf. Faustova, 1984 and.references therein . On the basis of several OSL

dates from the River Vaga valley, adjacent to theŽ .present study area, Larsen et al. 1999 concluded

that the maximum position of the Scandinavian IceSheet there was attained after ca. 17 ka, whiledeglaciation from the area started at ca.14.8 ka. TwoOSL dates presented in this paper from the Kirillovpit suggest that the Scandinavian Ice Sheet reachedits maximum position between 19.3"1.2 and 17.6"1.3 ka in the Kubenskoye–White Lake area. Thisage estimate for the LGM is comparable to that

Ž .obtained by Larsen et al. 1999 , although the icemight have reached its maximum a little earlier in

the Kubenskoy–White Lake area compared to that ofthe northern Vaga basin.

A curve illustrating the onset of the ScandinavianIce Sheet glaciation during the late Middle and Late

Ž .Valdai Weichsel can be presented, knowing the ageestimate of the LGM for the southern part of the

Ž . 14study area Fig. 7 . Since new AMS C-dates formammoth bones from the Late Weichselianglacigenic sediments across Finland are now avail-

Ž .able Ukkonen et al., 1999 and range from 33 000 to25 000 cal BP some preliminary discussion of the icegrowth can be given. Since mammoths did occur insouthern Finland as late as 25 000 cal BP, it seemsobvious that the growth rate of the Scandinavian IceSheet was very fast. According to calibrated14Cdatings and OSL results the build up of ice fromsoutheastern Finland to the LGM position, some1000 km southeast in the northwestern Russian Plain,

Ž .took only 7000 years. Saarnisto and Saarinen 2001

Fig. 7. Glaciation curve for the growth and decay of ice in the southeastern sector of the Scandinavian Ice Sheet. Ages for the ice growth are14 Ž .based on OSL dates at Kirillov and on previously published AMS C-dates on mammoth bones from Finland Ukkonen et al. 1999 . Dates

14 Ž .for deglaciation are based on paleomagnetics, varve chronology and calibrated C dates presented by Saarnisto and Saarinen 2001 .Ž .Numbers in the inset: 1sGulf of Bothnia the Ii River , 2sHaapajarvi, 3sNilsia, 4sKirillov, 5 ssouthern shore of Lake Onega,¨ ¨

6sHelyla, northern part of Lake Ladoga, 7s the Second Salpausselka.¨ ¨

( )J.P. Lunkka et al.rGlobal and Planetary Change 31 2001 407–425424

present their results for the deglaciation of the Scan-dinavian Ice Sheet from Lake Onega to the SecondSalpausselka in southern Finland. Taking these re-¨sults and the age estimate of the LGM at ca. 18 kainto account, it can be concluded that the ice retreatfrom Lake Kubenskoye to the northern parts of Lake

Ž .Ladoga and Lake Onega took ca. 5 ka Fig. 7 ,approximately 60–80 mryear.

Environments in the study area at and after theLGM are slightly revised by us, compared to e.g.

Ž .Kvasov 1979 . The average water level of glaciola-custrine basins stood around 130 m a.s.l. in thesouthern part of the study area and the drainage wastowards the south via River Volga. In the Vagabasin, lacustrine conditions could also have existedŽ .e.g. Kvasov, 1979 and the drainage was mostprobably towards the south into the Sukhona rivervalley. Later, when ice retreated, the drainageswitched towards the northeast as indicated in Fig. 6.

9. Conclusions

Based on the results presented in this paper, thefollowing main conclusions can be made:

Ž .1 Previous estimates on the extent of the LastŽ .Glacial Maximum LGM are slightly too large.

Ž .2 The Scandinavian Ice Sheet reached its maxi-mum in the Lake Kubenskoye area ca. 18 ka. Thisestimate is similar to that obtained by Larsen et al.Ž .1999 in the northern Vaga area. However, it seemsthat the ice reached its maximum position a thousandyears earlier in the Kubenskoye–White Lake areathan in the Vaga area.

Ž .3 A preliminary age model for the ice growth ofthe Scandinavian Ice Sheet from southern FinlandŽ .25 000 cal BP to its maximum position in the NW

Ž .Russian Plain ca. 18 000 ka suggests that the icegrowth rate was relatively fast and took only 7000years.

Acknowledgements

The authors express their gratitude to TuoviŽKankainen the Radiocarbon Laboratory of the Geo-

.logical Survey of Finland and Dr Andrew MurrayŽthe Nordic Laboratory of Luminescence Dating at

.Risø, Denmark for dating results. This work wasfinanced by the EC Environment and Climate Re-

Žsearch Programme Eurasian Ice Sheets, contract no..ENV4-CT97-0563 . Funds from the Academy of

Ž .Finland project nos. 41934 and 44263 are alsoacknowledged.

References

Aikaa, O., Mantynen, P., Kankainen, T., 1992. High-performance¨¨ ¨14C gas-proportional counting system applying pulse-shapediscrimination. Radiocarbon 34, 414–419.

Arslanov, Kh.A., Auslender, V.G., Gromova, L.I., Zubkov, A.I.,Khomutova, V.I., 1970. Paleogeography and absolute age ofthe Valday glacial maximum near lake Kubena. DokladyAkademii Nauk SSSR 195, 1395–1398.

Arslanov, H.A., Breslav, S.P., Zarrina, E.P., Znamenskaya, O.M.,Krasnov, I.I., Malakhovskiy, D.B., Spiridonova, E.A., 1981.Climatostratigraphy and chronology of the Middle Valdai inthe northwest and center of the Russian Plain. In: Velichko,

Ž .A.A., Faustova, M.A. Eds. , Pleistocene Glaciations of theEast European Plain. Nauka, Moscow, pp. 12–27.

Bouchard, M.A., Gibbard, P.L., Salonen, V.P., 1990. Lithostrato-types for Weichselian and Pre-Weichselian sediments in south-ern and western Finland. Bulletin of the Geological Society ofFinland 62, 79–95.

Denton, G.H., Hughes, T.J., 1981. The Last Great Ice Sheets.Wiley, New York, 484 pp.

Faustova, M.A., 1984. Late Pleistocene Glaciation of EuropeanŽ .USSR. In: Velichko, A.A. Ed. , Late Quaternary Environ-

ments of the Soviet Union. Longman, London, pp. 3–12.Faustova, M.A., 1995. Glacial stratigraphy of the Late Pleistocene

in the northwestern part of the Russian plain. In: Ehlers, J.,Ž .Kozarski, S., Gibbard, P. Eds. , Glacial Deposits in North-East

Europe. A.A. Balkema, Rotterdam, pp. 179–182.Faustova, M.A., Gribchenko, Y.N., 1995. Lithology of glacial

deposits of the last Late Pleistocene glaciation. In: Ehlers, J.,Ž .Kozarski, S., Gibbard, P. Eds. , Glacial Deposits in North-East

Europe. A.A. Balkema, Rotterdam, pp. 183–188.Gey, V., Malakhovskiye, D., 1998. On the age and extension of

the maximum upper Pleistocene glaciation in western Vologdaarea. Izvestija Russkogo Geographicheskogo Obschestva 1,43–53.

Gey, V., Saarnisto, M., Lunkka, J.P., Demidov, I., 2001. Mikulinoand Valdai paleoenvironments in the Vologda area, NW Rus-sia. Global and Planetary Change 31, 347–366.

Grichuk, V.P., 1984. Late Pleistocene vegetation history. In:Ž .Velichko, A.A. Ed. , Late Quaternary Environments of the

Soviet Union. Longman, London, pp. 155–178.Grosswald, M.G., 1980. Late Weichselian ice sheet of northern

Eurasia. Quaternary Research 13, 1–32.Grosswald, M.G., 1998. Late-Weichselian Ice Sheets in Arctic

and Pacific Siberia. Quaternary International 45r46, 3–18.Hirvas, H., Lintinen, P., Lunkka, J.P., Erikson, B., Gronlund, T.,¨

( )J.P. Lunkka et al.rGlobal and Planetary Change 31 2001 407–425 425

1995. Sedimentation and lithostratigraphy of the Vuosaarimultiple till sequence in Helsinki, southern Finland. Bulletinof the Geological Society of Finland 67, 51–64.

Kitagawa, H., van der Plicht, J., 1998a. Atmospheric radiocarboncalibration to 45,000 yr B.P.: late glacial fluctuations andcosmogenic isotope production. Science 279, 1187–1190.

Kitagawa, H., van der Plicht, J., 1998b. A 40,000-year varvechronology from Lake Suigetsu, Japan: extension of the14Ccalibration curve. Radiocarbon 40, 505–515.

Ž .Krasnov, I.I. Ed. , 1971. The Map of Quaternary Deposits of theEuropean Part of the USSR and Adjacent Areas, 1:1 500000.Ministerstvo Geologii SSSR.

Krasnov, I.I., Duphorn, K., Voges, A., 1971. InternationaleQuartar-Karte von Europa, 1:2500000. Blatt, Moskva. Bunde-¨sanstalt fur BodenforschungrUNESCO 1971.¨

Kvasov, D.D., 1979. The Late-Quaternary history of large lakesand inland seas of eastern Europe. Annales Academiae Scien-

Ž .tiarum Fennicae, Series A III 127 , 71 pp.Larsen, E., Lysa, A., Demidov, I., Funder, S., Houmark-Nielsen,˚

M., Kjaer, K., Murray, A.S., 1999. Age and extent of theScandinavian ice sheet in northwest Russia. Boreas 28, 115–132.

Mangerud, J., Svendsen, J.I., Astakhov, V.I., 1999. Age andextent of the Barents and Kara ice sheets in Northern Russia.Boreas, 28, 46–80.

¨Mantynen, P., Aikaa, O., Kankainen, T., Kaihola, L., 1987.¨ ¨¨Application of pulse-shape-discrimination to improve the pre-cision of the carbon-14 gas-proportional-counting method. In-ternational Journal of Applied Radiation and Isotopes 38,869–873.

Miall, A.D., 1978. Lithofacies types and vertical profile models inŽ .braided river deposits: a summary. In: Miall, A.D. Ed. ,

Fluvial Sedimentology. Canadian Society of Petroleum Geolo-gists, Memoir, pp. 597–604.

Miall, A.D., 1984. Architectural-element analysis: a new method

of facies analysis applied to fluvial deposits. Earth-ScienceReviews 22, 261–308.

Saarnisto, M., Salonen, V.P., 1995. Glacial history of Finland. In:Ž .Ehlers, J., Kozarski, S., Gibbard, P. Eds. , Glacial deposits in

North-East Europe. A.A. Balkema, Rotterdam, pp. 3–10.Saarnisto, M., Saarinen, T., 2001. Deglaciation chronology of the

Scandinavian Ice Sheet from the Lake Onega Basin to theSalpausselka end moraines. Global and Planetary Change 31,¨387–405.

Sudakova, N.G., Faustova, M.A., 1995. Glacial history of theŽ .Russian Plain. In: Ehlers, J., Kozarski, S., Gibbard, P. Eds. ,

Glacial deposits in North-East Europe. A.A. Balkema, Rotter-dam, pp. 151–156.

Svendsen, J.I., Astakhov, V.I., Bolshiyanov, D.Yu., Demidov, I.,Dowdeswell, J.A., Gataullin, V., Hjort, C., Hubberten, H.W.,Larsen, E., Mangerud, J., Mellers, M., Moller, P., Saarnisto,¨M., Siegert, M.J., 1999. Maximum extent of the Eurasian icesheets in the Barents and Kara Sea region during the Weich-selian. Boreas 28, 234–242.

Ukkonen, P., Lunkka, J.P., Jungner, H., Donner, J., 1999. Newradiocarbon dates from Finnish mammoths indicating largeice-free areas in Fennoscandia during the Middle Weichselian.Journal of Quaternary Science 14, 711–714.

Velichko, A.A., Faustova, M.A., 1986. Glaciations in the EastEuropean region of the USSR. Quaternary Science Reviews 5,447–461.

Velichko, A.A., Isayeva, L.L., Makeyev, V.M., Matishov, G.G.,Faustova, M.A., 1984. Late Pleistocene glaciation of the Arc-tic Shelf, and reconstruction of Eurasian Ice Sheets. In:

Ž .Velichko, A.A. Ed. , Late Quaternary Environments of theSoviet Union. Longman, London, pp. 35–44.

Velichko, A.A., Kononov, Yu.M., Faustova, M.A., 1997. The lastglaciation of Earth: size and volume of the ice-sheets. Quater-nary International 41r42, 43–51.