No abstract

Detailed sedimentological studies and parallel sampling for 14C and infra-red stimulated luminescence age assays were undertaken at six sites lying beyond and below the tree-line with the objective of establishing the historical development of aeolian landforms in Lapland. The main issues were: (a) the timing of dune activity and processes of stabilization; (b) the specific processes responsible for the past and contemporary activity. New data indicate that many of the primary dunes were active for several millennia after deglaciation. Diachronous stabilization at both local and regional scales appears likely. Initial stabilization occurred in local interdune areas and where regional dune fields were colonized by pine (generally before 7 ka). Local large dunes and some regional dunefields only became stable around 4.3 ka, when the regional groundwater table rose and late pine colonization was possible. The latest episode of aeolian activity dates from ad 1100–1650 across the area. A unique deflation triggering factor was not identifiable, suggesting that several agents acted in combination. Climate-vegetational parameters, especially the‘Little Ice Age’ event, together with reindeer trampling, appear responsible for the continuing aeolian activity at the tundra sites. At the margin of the pine forest zone, forest fires may be the cause of aeolian reactivation.

No abstract

A section excavated through two adjacent turf-banked solifluction lobes has revealed buried soils beneath each solifluction sheet. Five radiocarbon dates are reported from the buried soils and these reveal evidence of soil movement which probably extends over nearly 3,000 years until the present. The initiation of the movement appears to be linked to the late Sub-Boreal climatic deterioration and Neoglacial glacier expansion which induced the development of a late-lying snow patch at the study site. The first period of movement appears to have been faster than that during the later phase. It is suggested that this reduced rate is associated with a decrease in slope angle and to increased distance from the latelying snow bank at the head of the slope, rather than to a less severe climatic environment. RÉSUMÉ. Indices de solifluxion néoglaciaire d Okstindan, dans le nord de la Norvège. Une section creusée à travers deux lobes de solifluxion adjacents et bordés de gazon a révélé la présence de sols enfouis sous chaque nappe de solifluxion. Les auteurs présentent cinq radiodatations de ces sols enfouis, qui donnent la preuve d'un mouvement du sol qui s'étend probablement sur 3,000 ans jusqu'au Présent. Le début de ce mouvement semble lié à la détérioration du climat à la fin du Subboréal et B l'expansion des glaciers au Néoglaciaire, qui ont provoqué le développement d'une flaque de neige tardive sur le site étudié. La première période de mouvement semble plus rapide que la seconde. Les auteurs suggèrent que ce ralentissement est lié à une réduction de la pente et à I'éloignement progressif du banc de neige tardif au sommet de la pente, plutôt qu'à un milieu climatique moins sévère.