360 THORLEIFUR EINARSSON 



the high point of the Last Glacial was more than 100 m lower than today. 

 Due to these facts there have probably been ice-free and dry areas also on the 

 northern coastal shelf of Iceland. 



The present interpretation of the pollen diagrams seems to support the 

 opinion of botanists (Steindorsson, 1954; Love and Love, 1956) that a part of 

 the Icelandic flora has survived on ice-free areas during the Last Glacial 

 (see also Fig. 3). 



The Betula immigrates rapidly into southern Iceland about 9000 B.P. as 

 the Sogamyri diagram (Fig. 2) indicates. The diagram then shows the first 

 5eri//fl-maximum followed by the Atlantic Betula-mmimma.. The younger 

 Betula-msLXivmxm. is thereafter very distinct. The slight rise of the Betula-curve 

 in pollen zone D (historic time) may be a result of re-bedded pollen grains 

 that were blown into the bogs from the hills in the vicinity. The loess soils 

 were eroded very rapidly in historic times and the dust, too, was re-bedded 

 partly in the bogs. 



Raised beaches are known in all parts of Iceland (Fig. 7). The evidence of 

 higher sea-level are gravel terraces, old sea-cliffs and bedded marine clays with 

 sub-fossil molluscs. The height of the marine hmit differs from place to place 

 in Iceland. In southern Iceland (Holt, Hreppar, Landssveit) the marine Hmit 

 is ca. 1 10 m, at Reykjavik ca. 45 m, in Borgarfjordur 80-100 m, and in western, 

 northern, eastern, and southeastern Iceland 40-50 m, i.e. the raised beaches 

 are much lower at the coast than farther inland. The highest shorehne seems 

 to be synchronous all over the island. The varying height of the raised beaches 

 is a result of the different downwarping of Iceland caused by the ice-sheet 

 during the last glaciation, and of the subsequent isostatic recovery. 



The age of the highest shoreline is still not definitely known. The first 

 investigators believed, that the marine limit was of Post-glacial age according 

 to the heat-demanding molluscs in the raised marine deposits (all these sub- 

 fossil molluscs exist today along the Icelandic coast), equating the Late 

 Glacial Icelandic subfossil mollusc fauna with that of Scandinavia, without 

 regard to the great eustatic changes of sea level and the different land-sea 

 distribution in the Pleistocene. The Gulf Stream had much more influence on 

 the Icelandic coast during the Glacials, and especially in Late Glacial times, 

 than it did on the coasts of Scandinavia. According to Kjartansson (1958) the 

 sea level had sunk approximately 10-15 m below its maximum height at the 

 end of the Budi stage. He concludes, that the Biidi stage may be comparable 

 to the Salpausselka-Raerne stage in Scandinavia, i.e. Younger Dryas. Pollen- 

 analytical studies by the present author indicate that the highest shorelines 

 are probably older, but in the absence of C^^ datings this cannot be definitely 

 stated yet. 



The isostatic recovery was relatively rapid, as the sea level had reached the 

 present level by 9000 B.P. The lagoon Seltjorn near Reykjavik was isolated 

 at this time and normal peat formation started in the basin. Only the deepest 



