Research Note Holocene shoreline displacement in southernmost Spitsbergen WIESLAW ZIAJA and Om0 SALVIGSEN Ziaja, W. & Salvigsen, 0. 1995: Holocene shoreline displacement in southernmost Spitsbergen. Polar Research 14(3), 339-340. Three radiocarbon dates on marine organic material from southernmost Spitsbergen are presented, making it possible t o compare the Holocene shoreline displacement in this area with that of other areas of Svalbard. The most distinct raised beach feature is the large beach ridge terrace about 10 m above sea level which most probably is the result of a marine transgression ca. 6500 years ago. Dating of 2700-year-old laminaria from about 2 m above sea level demonstrates a small rising of the land during the youngest Holocene. Wieslaw Ziaja, Jagiellonian University, Institute of Geography. Grodzka 64, 31-044 Krakbw, Poland; Otto Salvigsen, Norsk Polarinrtitutt, Middelthunsgate 29, P . 0. Box 5072 Majorstua. N-0301 Oslo, Norway. A great variety of well-developed raised beaches occur in southernmost Sorkapp Land (Fig. 1). This note deals with marine deposits and features from the middle- and late-Holocene. The main objective is to demonstrate an eastward increase in shoreline displacement in southernmost Spits- bergen. Other forms of relief and Quaternary deposits have been described by Wdjcik & Ziaja (1993). Three samples of marine organic material col- lected from Sorflya (Fig. 1) in 1991 have been dated (Table 1). Two dates are from the large beach ridge terrace about 10 m above sea level. This prominent geomorphological feature can be followed continuously for a distance of many kilo- metres (Fig. 1). A whale bone found on top of the ridge terrace 10-20cm below the surface revealed an age of 6465 ? 105 yrs B.P. (T-10860). An identical age was obtained by dating a lami- naria layer in the ridge, 9.5m above sea level and 0.7 m below the surface, 6440 * 55 yrs B.P. (T-10859). The latter is a confirmation of a former dating of laminaria from the same site, 6580 & 160 yrs B.P. (Gd-6583) reported by Wojcik & Ziaja (1993). A few kilometres t o the northeast from this site (Bettybukta), a whale bone found 9.5 m above sea level revealed the age 6580 ? 50 yrs B.P. (SRR-2174 in Forman 1990). Dating of a layer of laminaria from the left bank of the river near to Skjemmeneset and Sorkapphytta, about 2 m above sea level, resulted in the age of 2715 ? 85 yrs B.P. The radiocarbon dates presented here are in good accordance with the shoreline diagram for northwestern Sorkapp Land presented by Salvig- sen & Elgersma (1993). Their conclusion was that the Holocene transgression there was completed about 7500 years ago and was followed by a relatively stable sea level for about 2000 years. The transgression resulted in a large beach ridge Table 1. Radiocarbon dates from southernmost Spitsbergen, Svalbard Lab. No. Field No. Elevation (m) Site Material Age ''C yrs B . P . T-10861 (1) 0.2 Skjemmeneset laminaria 2715 * 85 T-10860 (2) 10 Aurodden whale bone 6465 ? 105 T-10859 (3) 9.5 Mathiasbreen laminaria 6440 ? 55 Gd-6583 W6jcik & Ziaja 1993 9.5 Mathiasbreen laminaria 6580 2 160 340 W . Ziaja & 0. Salvigsen I.=lsfjorden H.=Homsund B.=Bellsund F i g . I. Location map showing the main geomorphologic featurea of southernmost Scrkapp Land 1. Three sitcs of radiocarbon dated material indicatcd by field nos. "C 111 (Skjemmeneset). "C ['I (Aurodden). and "C [3] (Mathiasbreen, forefield) (see also Table 1). 2 Holocene terraced coastal plaina. Serflya and GrunnvAgsletta. up to 19 m a.s.1. 3. The main heach ridge terrace, 10 m i l . s . I . 1 . Fluvial deposits and allu\,ial fans. S . Glaciofluvial extramarginal deposits. 6. Old skerries of Trollstabbane and Scrflyrabbane nith fraxments of raised marine terrace5 2@-10m a.s.1. 7 . Lakes. 8. Solifluction sediments. 9 . Marginal zones of glaciers. 10. Glaciers and perennial snow 1 1 . Moraines and rock glaciers. 12 Rocky slopes with B thin cover of weathered material. 13. Rocky wrfaces o i raised cliffs. tcrracea and former skerries. The inset map shows Isfjorden ( I ) . Bellsund (B) and Hornsund (H). terrace which can be followed along the western coast from Sorkapp to north of Isfjorden (Landvik et al. 1987; Salvigsen et al. 1990: Salvigsen et al. 1991). The top level of this ridge shows some vari- ations in altitude from 1 0 m between Isfjorden and Bellsund (Landvik et al. 1987) t o 7 m o n the coast south of Hornsund (Salvigsen & Elgersma 1993). The crest level of the large beach ridge in southernmost Sorkapp Land has been repeatedly determined by a Paulin altimeter in such a way that the uncertainty is less than 2 1 m. W e can therefore conclude that the crest level there is about 3 m higher than the crest level in north- western S s r k a p p L a n d . This indicates that the southernmost part of Spitsbergen also shows an increased shoreline displacement from the west towards the east during the last 6500 years. W e think that the pattern of relative uplift is mainly caused by different isostatic depression during the last glaciation. Thus. our observations indicate a heavy Late Weichselian glaciation in the sea east of southernmost Spitsbergen. References Forrnan. S. L (comp.) 1990: Svalbard Radiocarbon Date List 1. Occasimal Paper N o . 47. INSTAAR, Boulder. 48 pp. Landvik. J . Y . Mangerud, J . & Salvigsen. 0. 1987: The Late Weichselian and Holocene shoreline displacement on the west-central coast o f Svalbard. Polar Rrs. 5 ms., 2 9 - 4 4 Salvigsen. 0.. Elgersma. A , , Hjort, C.. Lagerlund, E . . Liestldl, 0. & Svensson, N . - 0 . IYYO: Glacial history and shoreline displacement on Erdrnannflya and Bohemanflya. Spitsbergen. Svalbard. Polar Rer. 8, 261-273. Salvigsen, 0.. Elgersma, A . & Landvik, J . Y . 1991: Radio- carbon dated raised beaches in northwestern Wedel Jarlsberg Land. Spitsbergen. Svalbard. W y p r a l r y Gcograficmr /la Spifsbergen. %l6. Salvigsen, 0 . 8: Elgersma. A . 1993: Radiocarbon dating of deglaciation and raised beaches in north-western S@rkapp Land. Spitsbergen. Svalbard. Zesz. Nuuk. UJ, Prace Geogr. 94. 39-48. Wojcik. A . & Ziaja, W . 1993: Relief and Quaternary of southern Sarkapp Land, Spitsbergen. P o l . Polar Res. 14(.3). 29S308.