Brown earth and podzol: soil genesis illuminated by microfossil analysis

Andersen, S. Th. 1979 03 01: Brown earth and podzol: soil genesis illuminated by microfossil analysis. Boreas , Vol. 8, pp. 59–73. Oslo. ISSN 0300–9483.
Pollen and other plant microfossils were studied in soil profiles from a Fagus-Quercus petraea woodland in eastern Jutland, Denmark. Fungal hypha fragments in the soil show characteristic length frequency distributions, which indicate comminution by large arthropods and microarthropods (Oribatei) during the burial. Distribution of the hypha fragments within the podzol indicates development from a former brown earth. The pollen sequence in a humus deposit reflects recent vegetational development. Modification of pollen assemblages in the mineral soils can be explained by mixing during burial by soil fauna. Development from brown earth to podzoloid and podzol follows the models assumed by pedologists. The various stages are related to vegetational changes and the processes were completed within a few hundred years.     

The deglaciation between Skjerstadfjord and Svartisen, north Norway

Six successive zones with distinctive marginal moraines are recognized. Based on radiocarbon dates the ages of the three oldest zones are believed to be: older than 11,100 years B.P. (Vasdal event), about 10,900 B.P. (Glomfjord-Straumöy events), and between 10,400 and 9500 B.P. (Skjerstad event). The three youngest zones are Preboreal. Corresponding marine sediments, shorelines, glaciation limits and other glacial features are described.     

Sedimentation in ice-covered Lake Hoare, Antarctica

The sedimentation mechanisms that occur in ice-covered Lake Hoare, Antarctica are examined, to determine how sediment enters the lake, and how the sedimentation pattern affects blue-green algal growth at the lake bottom. The 3 m-thick ice cover contains pebbly sand as much as 2 m below the surface. Sediment with similar texture and mineralogy is found at the lake bottom. This evidence, together with the lack of sediment in the inflowing stream and the markedly different texture of sediment from the other terrains around the lake suggest that most of the sediment at the lake bottom comes in through the ice cover. Sand grains intermittently migrate through porous ice on the surface, water-filled vertical gas-channels penetrating two-thirds of the ice cover, and possibly through cracks in the ice that act as conduits. The algae at the lake bottom are able to survive in part because sediment that comes through the ice cover does not obliterate them.     

The deglaciation of Norway after 10,000 B.P.

Several distinctive marginal moraines of Preboreal age have been observed in Norway. They are grouped into three major morainal zones that are radiocarbon dated at about 9900±100, 9600±100 and 9300±100 B.P. respectively. The following deglaciation of central Norway was rapid and most likely completed about 8500 B.P. Evidence of glacier fluctuations up to recent time is discussed. The results are based partly on observations by the field parties of the I.G.C.P. project 'Quaternary Glaciations in the Northern Hemisphere'.     

Quantitative study of the distributary braidplain of the Preboreal ice-contact Gardermoen delta complex, southeastern Norway

This raised delta structure is an ice-contact deltaic complex with a volume of c. 4.4.10⁹ m³, deposited c . 9500 yr BP in a shallow wide 'fjord' during the retreat of the Scandinavian ice cap. The delta plain lies at an altitude of 200–223 m. It aggraded c . 20 m above the contemporaneous sea level during a regional marine regression. The braidplain palaeochannel characteristics indicate a peak meltwater discharge of 7–9 10³ m³/s. Calculations based on a glacial ablation model indicate a mid-summer discharge of c . 5.5 10³ m³/s. However, the fluvial topset of the delta has an erosive base whose altitude decreases upstream and indicates stream incision by more the 6 m below the contemporaneous sea level. The deep scour is ascribed to episodic floods over the relatively short delta plain, which exceeded direct ablation-associated discharges. The depositional time-span of the delta is assessed to have been 70 years, calculated from coastal gradient and shoreline displacement curves. The average sedimentation rate of the delta is thereby inferred to have been extremely high, c . 6. 10⁷ m³/yr. The sedimentation is thought to reflect 'extreme' ice-margin conditions, where the sediment and water discharge was maximized by full-scale ablation, with simultaneous subglacial, englacial and supraglacial sediment and water supply. These conditions might further coincide with an abundant rainfall in the catchment area or the drainage of dammed waters, initiating episodic floods which eroded deep beneath sea level. As a whole, the study illustrates the hydrological conditions of proglacial sedimentation at the front of the rapidly retreating last Scandinavian ice cap.     

Size, age and spawning frequency of landlocked arctic charr Salvelinus alpinus (L.) in Svartvatnet, Svalbard

This contribution reports the analysis of a sample of landlocked arctic charr collected with gillnets in Svartvatnet, Svalbard, 1964. This is the first scientific sample from a landlocked charr population from Svalbard. We found a very prominent modal group of large, old and sexually adult fish of both sexes. Their length ranged from 15 to 62 cm, but 92% of the fish were longer than 40 cm and 62% of them fell in the 45 to 54 cm interval. The age range was 7 to 31 years, but 93% were 14 years or older and represented 18 year-classes. The length-at-age of the charr seemed to increase steadily until they reached the size and age of the modal group. The growth rate decreased sharply after that. The mortality rates within the age span of the modal group seemed to be low. The ages at first spawning for most of the charr in the sample were between 7 and 9 years and spawning cycles of two years were indicated.     

Weichselian before 15,000 years B.P. at Jæren-Karmø in southwestern Normay

On the basis of studies of many stratigraphical profiles, together with radiocarbon dates, Thorium-Uranium dates and amino-acid dates, the following preliminary stratigraphy is proposed: (1)Late Weichselian. Stavanger Stadial. The glacier covered the coast and deposited the upper drift sheet. - (2) Middle Weichselian.(a)Sandnes Interstadial (30,000?-39,000 years B.P.). Thick units of marine deposits underlie the Stavanger Stadial drift. The lithology, the foraminiferal fauna, the molluscan fauna and the pollen flora all record cold, partly near-ice environment during their deposition. Elements of a boreal type foraminiferal fauna suggest that certain phases of the Sandnes Interstadial could have been slightly warmer. The shore level was very high. (b) Jæren Stadial (40,000? 1000 years B.P.). Tills and glaciomarine deposits at several locailites are correlated with a Jæren Stadial. (c) Nygaard Interstadial (41,000–50,000? years B.P.). Marine deposits representing a low shore-level phase, record cool to cold conditions. - (3)Early Weichselian. (a) Karmøy Stadial (older than 47,000 years B.P.). Gravelly and very bouldery tills at low stratigraphical levels in several prifles are correlated with a Karmøy Staidial.(b) Older deposits. Marine deposits which lie below the Karmøy Stadial till and on top of Eemian deposits at Bø II on Karmøy are being studies.