En undersøkelse av kvartære, økostratigrafiske soner i Drammen, på grunnlag av foraminiferer.

Abstract

1. The present paper is a report on a quantitative study of the fossil, benthonic foraminifera of Late- and Post-Galcial clay samples from Drammen, Norway. 2. On the basia of their content of foraminifera, it has been possible to divide the marine clays in the Drammen area into four ecostratigraphical zones, D, E, F, and G, in accordance with the zonation established by Rolf W. Feyling-Hanssen from the Oslofjord area, of which D being of Late-Glacial age; E, F and G of Post-Glacial age. 3. An attempt has been made to correlate the foraminiferal zones in Drammen with W.C. Brøgger's classical division based on Mollusca. 4. The reduced foraminiferal fauna from D, indicating originally brackish environments, combined with thick sediment deposits from the same period, may be seen in connection with a large supply of melt-water to the area, and a partial closing of the inner fjord basin by the Svelvik moraine. 5. The sharp faunistic transition between the zones D and E, must be the result of a climatic amelioration, as for the whole Oslofjord area. 6. Comparisons made between F in the Drammen and Oslofjord area, show that the fauna is more reduced in the upper part of the zone in the former area, probably because of a lowering of a salinity.