ABSTRACT

Institutt for plante- og miljøvitenskap

Orstad is an Early Bronze Age clearance cairn field in a cultural landscape in the municipality of Klepp, at Jæren, in southwest Norway, with traces of land use back to the Neolithic. Soil pollen analysis, soil micromorphology, pF- analysis, and standard soil-analytical methods, were combined to reconstruct the land use history on the site with focus on the time from the Late Neolithic to the Early Iron Age, and to elucidate the potential of soil pollen analysis for such reconstructions. Samples were taken from an 84 m long excavated trench with mainly podsolic soils, and from two profiles, located about 10 m south of the southernmost point of this trench.

Five phases of the local vegetation- and land use history were reconstructed: From ca. 4500-4000 uncalibrated 14C years BP, the forested site has been locally cleared, and used for pasture. Then, the site was presumably not in use until ca. 3600 uncalibrated 14C years BP. From this time on, it seem to have been re-used for pasturing. Presumably, people sporadically cultivated barley and wheat on the middle part of the site, and wheat on the southwestern part of the site. The fields seem to have been made arable by fire-clearance. From about 3200 uncalibrated 14C years BP, and in the Early Iron Age, Orstad was possibly inhabited. The fields were moved further up the slope towards north, and obviously manured with podsolic and peaty topsoil material, transfered to the site from the vicinity. During the Early Iron Age, heather vegetation began to spread on the site. But on fields located outside of the investigated parts, cultivation presumably continued sometimes after. Heather vegetation, used for grazing, dominated on the site until recent times.

The partly low porosity in the soils at Orstad, locally presumably caused by the prehistoric cultivation activities, seem to have had a positive effect on the pollen preservation. In some profiles on the site, a slight relation between the pollen distribution and the variations in soil texture seem to be apparent. With increasing depth, an increasing share of the pollen grains recorded in the thin sections was found in void spaces and not in the matrix material. This result may indicate processes of transport with the water flow. Site-specific studies of pollen in thin sections and their relations to void spaces, and of soil hydraulic properties, may therefore be useful tools to select or reject certain soil layers for palaeoecological reconstructions.


LIST OF PAPERS
Paper I. Sageidet, B.M. (in press). Soil pollen analysis of a podzol and a clearance cairn, confirms Bronze Age Agriculture at Orstad, Southwestern Norway. Journal of Nordic Archaeological Science 15 (2005).

Paper II. Sageidet, B.M. (2005). Sub-local differences in Late Holocene land use at Orstad, Jæren in SW-Norway, revealed by soil pollen stratigraphy. Environmental Archaeology 10,1, 51-71.

Paper III. Sageidet, B.M. & Sørensen, R. (submitted). Soil micromorphological evidence to soil deposition and late Bronze Age/Early Iron Age turf manure at Orstad, southwestern Norway. Submitted to Geoarchaeology (02.12.04).

Paper IV. Sageidet, B.M., Tau Strand, L. & Haugen, L.-E. (manuscript). Pollen distributions in the soils at Orstad, Klepp in SW-Norway, elucidated by pollen records, thin section studies and soil hydraulic properties.



Oppdatert: 16.08.05
Utskriftsvennlig versjon : Arkiv : Tips en venn