Geoffrey D. Corner

Asynchronous response of marine-terminating outlet glaciers during deglaciation of the Fennoscandian Ice Sheet

This is the accepted manuscript version. Published version is available at http://dx.doi.org/10.1130/G35299.1

Postglacial relative sea-level change and stratigraphy of raised coastal basins on Kola Peninsula, northwest Russia

A relative sea-level curve for the Holocene is constructed for Polyarny on the Kola Peninsula, northwest Russia. The curve is based on 18 radiocarbon dates of isolation contacts, identified from lithological and diatomological criteria, in nine lake basins situated between 12 and 57 m a.s.l. Most of the lakes show a conformable, regressive I–II–III (marine–transitional–freshwater) facies succession, indicating a postglacial history comprising an early (10,000–9000 radiocarbon years BP) phase of rapid, glacio-isostatically induced emergence (∼5 cm year−1) and a later phase (after 7000 years BP,) having a moderate rate of emergence (<0.5 cm year−1). Three lakes together record a phase of very low rate of emergence or slight sea-level rise at a level of ∼27 m a.s.l., between 8500 and 7000 years BP, which correlates with the regional Tapes transgression. Pollen stratigraphy in the highest lake shows that the area was deglaciated before the Younger Dryas and that previously reconstructed Younger Dryas glacier margins along the north Kola coast lie too far north.

Distribution of recent benthic foraminifera in a subarctic fjord-delta: Tana, Norway

Analysis of benthic foraminifera (living + dead fauna) in surface sediments from a deltaic and fjord environment at Tana, northern Norway, shows a marked contrast in foraminiferal assemblages between delta platform and delta slope-fjord basin provinces, and a correspondence between test abundance, percentage living of total foraminifera and inferred rate of sedimentation. The relatively shallow (<25 m), high-energy, sandy delta platform province is characterized by an absence or low abundance of foraminifera and a dominance of calcareous forms. Delta plain and tidal strait environments of this province contain a sparse Elphidium albiumbilicatum assemblage and a resedimented Cibicides lobatulus assemblage, respectively. The deeper (25–125 m), lower energy, silty-sandy to sandy-muddy delta slope-fjord basin province is characterized by a relatively high abundance of foraminifera and a dominance of agglutinated forms comprising an Adercotryma glomerata-Spiroplectammina biformis assemblage. Foraminiferal abundance in the delta slope-fjord basin province tends to increase with increasing depth and distance from the river mouth, suggesting a correlation with sedimentation rate. A generally high percentage of living foraminifera is thought to mainly reflect high sedimentation rates in the deltaic environment. Local variations in foraminiferal abundance, percentage living foraminifera, and faunal composition are ascribed mainly to local variations in sedimentation rates and processes, and postmortem changes.

Recent natural and anthropogenic changes in a regulated river delta: Elvegård, northern Norway

Digitized images of maps and aerial photographs of the Elvegard fjord–head delta, northern Norway, were compared to document recent (1912–1990) changes to the delta plain before and after river regulation in 1977 and sediment extraction since 1955, and to evaluate the role of natural and anthropogenic processes in deltaic evolution. A 1:4000 scale contoured reference map showing morphogenetic features in 1989 was constructed. Major changes to fluvial features on the delta plain before regulation include a 500 m westward shift of the outlet channel and formation and abandonment of several secondary channels. Little change has occurred following regulation. Wave processes before and after regulation have caused some beach erosion, slow filling of abandoned channels, and rapid growth of beach ridges where sediment extraction has disturbed equilibrium conditions.

Deglaciation of Fugløy, Troms, North Norway

Corner, G. D. 1978. Deglaciation of Fugloy, Troms, North Norway. Norsk geogr. Tidsskr. Vol. 32, pp. 137-142. Oslo, ISSN 0029-1951. The deglaciation of Fugloy is dated on the basis of raised shorelines and deglaciation limits. A probable lateral moraine of the Weichselian ice sheet is tentatively dated to pre-Bolling (Middle Weichselian). Cirque glaciation after the retreat of the Weichselian ice sheet is probably between Younger Dryas and Bolling in age.

A Younger Dryas moraine ridge and fjord delta in Valldal, Norddalsfjorden, Møre og Romsdal, Norway

The fjords and valleys of Norway have been shaped during several glacial cycles of the Quaternary period. Subaquatic ridges that formed at or close to the grounding lines of glacier termini during stillstands or readvances within the last deglaciation are commonly found within the fjords. An example is a prominent moraine ridge representing a readvance of the Fennoscandian Ice Sheet during the Younger Dryas ( c. 12.9–11.5 ka BP) in Norddalsfjorden, More og Romsdal, Norway. Fjord deltas may form in the same setting at the mouths of tributary valleys or at fjord heads following deglaciation. They may grow to relatively large dimensions and have morphological features that reflect the dynamic environment that exists across the fluvial–marine transition. One such delta is located close to, and partly drapes, the proximal slope of the moraine ridge at Norddalsfjorden. Norddalsfjorden is a narrow (0.8–3.5 km wide) and relatively deep (up to about 500 m deep) fjord situated between high mountain peaks and intermittent valleys (Fig. 1). A transverse, subaquatic ridge is situated on a bedrock sill just SW of the Valldal tributary valley. High-resolution multibeam data clearly depict the ridge as a well-defined topographic high with an arcuate crest that is convex down-fjord (Fig. 1c). The crest of the ridge is c. …

Using LiDAR data to characterize and distinguish among different types of raised terraces in a fjord-valley setting

Abstract Depositional terraces of diverse origin are common in Norwegian fjord valleys. They differ subtly morphologically and may be difficult to distinguish from one another without detailed field and stratigraphic investigation. We used LiDAR elevational data to describe previously identified glaciofluvial, glaciodeltaic, fluvial, and fluviodeltaic terraces in the Målselv valley, northern Norway, and show how they differ morphologically. Fluvial terraces are divided into two subtypes based on their difference in morphology. One type shows an undulating surface, often with a ridge-and-swale topography (scroll bars) associated with lateral accretion of moderate-to-high-sinuosity (meandering) channels, while the other shows remains of channels and braid bars associated with low-sinuosity channels. Fluviodeltaic terraces are generally flat and featureless, probably as a result of wave and tidal reworking of the terrace surface as it was raised above sea level. Glaciofluvial terraces show braided channel forms and occasional eolian dunes, while glaciodeltaic terraces are generally flat and featureless, in some cases having a moraine ridge on top and small beach ridges on the proximal, ice-contact slope. Terraces also show a distinct distribution pattern, with glaciofluvial and glaciodeltaic terraces graded to the marine limit occurring at higher elevations than fluviodeltaic and fluvial terraces. Based on the results presented here we show that a distinction can be made between different terraces based on morphological criteria revealed by LiDAR data. Such data should be acquired where possible to improve the quality of geomorphological mapping.