10 soil-samples for plant-macrofossil analysis were collected from 9 features related to the longhouse at Kvarnbo; and 5 samples – 4 from different post-holes and 1 from the wall construction – will this weekend travel to Uppsala in Sweden, where these will be analysed for plant-macrofossils at the Department of Archaeology and Ancient History, Uppsala University.
In general, plant macrofossil analysis (i.e. looking at the parts of plants preserved in the soil) is used in order to build up a picture of past environments, reconstruct past vegetation and, thereby, gain insight into past landscapes and their development; but this method can also provide important information about the use of structures in archaeology. The purpose of the plant-macrofossil analysis of Kvarnbo material is, however, first and foremost, to find datable material with low own age (for radiocarbon dating) such as, charred seeds – these can remain preserved in soil for a considerable time span and can sometimes be found in the absence of all other organic remains. Yet, using macrofossils for dating of features such as post-holes, it is important that the sample would come from the secondary fill of the post-hole, because only then there is a hope for the fill containing residues from the floor level of the construction and, thereby, be contemporary to the construction. The primary fill is the material that surrounds and supports the post once it has been installed, i.e. it is the backfilled earth connected to the installation of the post, and this fill is therefore not containing structure-contemporary plant-macrofossils (but might contain older material). In any case, post-holes are pretty good traps for macrofossils – after the post is removed from the construction, the hole is normally filled pretty fast again with the material from the surrounding. Inside a house, this fill-after-removing-the-post is often consisting of the floor; therefore, the analysis of the material from the post-hole might provide not only datable material, but also insight into the activities that have been going on in the vicinity of the post-holes.
Although only the very bottom of the post-hole features are preserved at the longhouse site in Kvarnbo, the samples sent to Sweden are all representative in terms of the amount of soil needed in order to run the analysis (every sample contains ca 2 liters of soil), also, all the samples were collected from the uncontaminated contexts meaning that these should not be corrupted by younger material from the subsequent use of the area. Now, it is only to hope that these will contain at least some plant-macrofossils, too (because, you know, these could be empty of such material as well………).