Otto Salvigsen

Deglaciation of Finnmark, North Norway

Altitude relationships between shore forms and their sea levels are investigated. Raised shore lines are measured in a large number of localities. Equidistant shore-line diagrams are constructed and used for relative dating purposes. Late Glacial shore lines older than the Main line (Younger Dryas time) seem to have larger gradients than assumed in previous studies. Selected glacial landforms are mapped and interpreted. In the investigated area, the ice reached beyond the coast of Finnmark during the last Glacial maximum. Distinct end moraines mark numerous halts during the subsequent ice recession. Margins of sub-stages are traced, and local glaciers and accumulation centres are located. The Main sub-stage moraines are best developed regionally. Important aspects of deglaciation patterns and ice-directed drainage are described. Streamlined forms are analysed in relation to topography, and axes of fossil inland dunes measured.

Northwest Svalbard during the last glaciation: Ice-free areas existed

The possibility that ice-free areas existed during the late Weichselian glaciation of the Svalbard archipelago has been debated for several decades. This study reveals the first geologic evidence that nunataks existed on the islands of northwest Svalbard. Several 10 Be exposure ages were obtained from bedrock and glacial erratics on Danskoya and Amsterdamoya Islands. Exposure ages for glacial erratics laid down in block-field‐covered plateaus .300 m above sea level show that the last ice sheet that completely covered the islands deglaciated .80 k.y. ago. Dating of marine sediments close to sea level reveals that full ice-free conditions were achieved by ca. 50 ka. During the late Weichselian, the coastal lowlands were glaciated, and the major fjords and troughs controlled glacier flow. The existence of nunataks at this time opens the possibility for glacial survival of plant species.

Radiocarbon-dated Mytilus edulis and Modiolus modiolus from northern Svalbard: Climatic implications

Eighteen new age determinations on Mytilus edulis shells from northern Svalbard and two new age determinations on Modiolus modiolus shells are presented. Mytilus edulis appeared on the northern coast of Spitsbergen c . 9400 yr BP. Its maximum extension there seems to have been c . 7250 yr BP, which is also indicative of a climatic optimum. The first finding of Modiolus modiolus shells from northern Spitsbergen is reported, and revealed the age of c . 8300 yr BP, which is also indicative of marine climatic optimum conditions. Mytilus lived at the head of Woodfjorden until at least 5300 yr BP, but it is not possible to date its final disappearance from the northern coast. Mytilus has been absent from large parts of the coasts of Svalbard during the entire Holocene, indicating limited influence of warm Atlantic water there. Recent reports of living Mytilus edulis on Bjørnøya indicate a probable new occurrence there, and the question about a further immigration to Spitsbergen should be kept in mind. Such a faunistic change may provide data about a more general climatic warming in this part of the Arctic.

Glacial history, Holocene shoreline displacement and palaeoclimate based on radiocarbon ages in the area of Bockfjorden, north-western Spitsbergen, Svalbard

Age determinations of bivalve shells indicate that Bockfjorden, a fjord in north-western Spitsbergen, Svalbard, was deglaciated shortly before 10 Kya, and that the upper marine limit in this area, with an altitude of about 50 m a.s.l., has the same age. During most of the Holocene, the glaciers in Bockfjorden were less extensive than they are today. Their maximum Holocene extension occurred during the Little Ice Age. The initial shoreline emergence after the deglaciation was rapid, and former shorelines younger than 8.5 Ky are below the present sea level. A mid- Holocene transgression of the sea is traced as well as a transgression during the last thousand years.

The seasonal water temperature cycle in the Arctic Dicksonfjord (Svalbard) during the Holocene Climate Optimum derived from subfossil Arctica islandica shells

Future climate change will have significant effects on ecosystems worldwide and on polar regions in particular. Hence, palaeo-environmental studies focussing on the last warmer-than-today phase (i.e. the early Holocene) in higher latitudes are of particular importance to understand climate development and its potential impact in polar systems. Molluscan bivalve shells constitute suitable bio-archives for high-resolution palaeo-environmental reconstructions. Here, we present a first reconstruction of early Holocene seasonal water temperature cycle in an Arctic fjord based on stable oxygen isotope (δ18Oshell) profiles in shells of Arctica islandica (Bivalvia) from raised beach deposits in Dicksonfjorden, Svalbard, dated at 9954–9782 cal. yr BP. Reconstructed maximum and minimum bottom water temperatures for the assumed shell growth period between April and August of 15.2°C and 2.8°C imply a seasonality of about 12.4°C for the early Holocene. In comparison to modern temperatures, this indicates that average temperature declined by 6°C and seasonality narrowed by 50%. This first palaeo-environmental description of a fjord setting during the Holocene Climate Optimum at Spitsbergen exceeds most previous global estimates (+1–3°C) but confirms studies indicating an amplified effect (+4–6°C) at high northern latitudes.