Deciphering the complexity of a 'simple' mesolithic phenomenon: Indicators for construction, use and taphonomy of pit hearths in Kampen (the Netherlands)

Pit hearth features form a common phenomenon in the Mesolithic of North-West Europe, and the Netherlands and adjacent parts of Germany and Belgium in particular. Using soil micromorphology, we investigated the genesis and taphonomy of several pit hearth features, embedded in sandy podzolic soils from Kampen (the Netherlands). This is one of the first studies to investigate one of such pits in its entirety, instead of only the lower, charcoal-rich fill. Our results show that the upper fill of these pits contains considerable amounts of noncharred degraded organic matter. The lower fill typically contains fragments of charcoal and some wood tar, but also black coatings around sand grains, that is interpreted as charred humus from a podzol B-horizon. These coatings indicate that material from the upper horizons of a podzol profile - e.g. in the form of turves - was used to control a fire on the floor of the pit. Fine charred material postdepositionally leached from the pit feature into the underlying deposits, associated with increased formation of limped clay coatings. This indicates that ash-induced alkaline charcoal degradation and associated clay translocation played a role in this process. The Kampen case provides strong evidence that fine charred organic material may contaminate underlying archaeological or sedimentary units.