388 SIGURDUR THORARINSSON 



whereas Einarsson (1958) regards it as Pliocene. The present author is 

 inclined to place it in the Giinz-Mindel Interglacial. According to Lindal, 

 leaf impressions of Dryas octopetala and Betula nana are common in these 

 sediments and on the whole they must indicate a somewhat colder climate 

 than does the Svinafell flora. But here one must take into account the 

 difference in climate between the Svinafell and the Bakkabrunir areas as 

 well. 



In the plant-bearing sediments at Ellidavogur no remnants of Alnus have 

 been found. If we regard these sediments as most likely belonging to the 

 Riss-Wijrm Intergalcial, a reasonable although not the only possible con- 

 clusion will be that Pinus possibly, but not likely, survived the Giinz Glacial, 

 that Alnus survived both Giinz and Mindel, but became thoroughly extinct 

 during the Riss Glacial, and that Betula survived all four main Pleistocene 

 Glacials. 



The investigation of the Svinafell layers is still in its early stages, and what 

 has been stated about them here is primarily intended to draw attention to 

 the fact that these are layers which require systematic and detailed research, 

 both macroscopic and microscopic, and both of the organic remains and of 

 the sediments as such. Morphometric measurements are particularly desirable. 

 The extent of the layers and their stratigraphy must also be more closely 

 investigated. 



What has been stated here about the need for closer investigation of the 

 Svinafell layers also applies to all other fossil-bearing interglacial sediments in 

 Iceland. There is probably no other place where so much of such sediments 

 has been preserved in a country that has been for the most part covered by 

 ice during the Pleistocene Glacials, the conditions for their preservation being 

 rather unique, as volcanoes were very active during both the Glacials and 

 Interglacials and sediments could therefore easily be covered either by lava or 

 tephra and thus be protected against glacial or fluvial erosion. Thorough and 

 systematic study of the fossil-bearing interglacial sediments in Iceland is one 

 of the most urgent tasks in the Quaternary geology of Iceland. 



ABSTRACT 



77?^ "'Svinafell layers"" are plant-bearing sedimentary deposits which form 

 the base of the mountain Svinafellsfjall in southeast Iceland. These deposits were 

 discovered in 1955 and have hitherto been only provisionally studied. The 

 minimum thickness of these sediments is 150 metres. Impressions of leaves are 

 abundant. Characteristic for the flora is the dominance o/' Alnus. 77?^ species 

 has been determined as A. viridis. Other trees that have grown in the area are 

 Betula sp., Sorbus sp. and probably Prunus padus, besides many species of 

 Salix. The flora indicates a climate as warm as now or somewhat warmer. 

 Stratigraphical and magneto-geological studies place the Svinafell layers in the 



