Sub-till sediments at Rokoberget, Southeastern Norway
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- Artikler 
A dark blue-grey, silty clay below till is described from a locality 230 m a.s.l. in the Rokosjøen depression east of Mjøsa. The sediment is glacially deformed but interpreted to represent a deposit from a period with local lake-level at least 240-250 m above present sea-level. The depositional environments are complex and believed partly to have been a shallow fjord embayment, but glaciolacustrine conditions may also have been involved. The pollen flora of the sediment is reflecting a grass-dominated, treeless, interstadial vegetation. Two 14C-AMS dates at c. 34 and c. 47 ka suggest a Middle Weichselian age for the sediments in the described Rokoberget inter- stadial. Similar glaciolacustrine\/lacustrine\/marine deposits may have been widespread in several periods, playing an important role as parent material for parts of the 'old blue tills' and overconsolidated sub-till sediments in the Mjøsa region. Possible correlations with other known interstadial deposits in southeastern Norway are discussed, but only fragments of the Weichselian development are known at the present time.