In 2015, in Lommel (Campine region, Belgium) we excavated a similar structure. We have two radiocarbondates: approximately 7.000 cal BC. Analyses for woodtar are still going on. We hope to publish early next year. You can contact me: [email protected] 

Closer to the truth?

For the last days we’ve discovered several further features of that type. Next to one of the objects we have also found a very well preserved concentration of burning of diameter about 50 cm (Fot. 1A) and thickness of about 5 cm max, with some kind of laminar slag inside. It looks very similar to the remains of kiln’s input after burning that we have in our experiments with a method of birch tar production without the use of ceramics. What is particularly interesting here, this is a “segregated” material, what means that we can distinguish three layers inside. The lowest part was probably lying on some type of container/plate because its surface is very flat, little bit wavy with a kind of rounding in some places, looking like a negative of the container’s wall over the bottom (fot. 1B). It consists of black powdered material, which is very cracked. It could be possibly an old birch tar because it looks (at the first glance) very similar to the substance of this type I’ve sampled recently from the Mesolithic slotted point from Tłokowo. The highest layer of the material consist mostly charcoals but also the remains of bark, that looks similarly to the birch one (Fot. 1C). Between these two layers it can be found a layer of a kind of very porous slag (Fot. 1D, E), that looks very familiar to the effect of pyrolysis of the birch bark. All together is very convincing but to be sure we must date the substance and make chemical analysis (for now we plan EDX, GC-MS and IR).

For now we can conclude that our hypothesis about the Mesolithic birch tar kilns on the Paliwodzizna site (taking also into consideration the information from Ferdi Geerts, for which I’m very grateful) looks even more likely. Of course if anyone has other suggestions we will be very grateful for them….

It would be good to do an analysis of the residues in and around the features to confirm the presence of birch-bark tar or other wood tars.  Many things can appear black when aged and/or heated so some chemical analysis is needed to confirm.  If these are truly wood tar kilns this would be very exciting as how it was produced in prehistory has always been a subject of lively discussion.

 Dear Valerie Steele, first of All thank You for interesting in our excavations and generally work. Of course we plan to make different chemical analyses (for now we have a possibility to make EDX, GC-MS and IR, what should give quite clear picture of what we are dealing with), similarly as precise dating of the features. Please remember that for us these structures are also something new, unexpected and really exciting. I fully agree that the confirmation of their suggested function could be something very important but must be properly documented to be reliable. This is also a reason I’ve asked this question. 

Ps. I’ve spent very nice week on the conference in Bradford last year, I like Your city a lot :-)

We have good data concerning the destilation of wood tar from the fragment of pottery dated to the paraneolithic layer on site Chwalim 1, western Poland. See: Jóźwiak at al. From the studies of manufacturing and utilisation of timber tar in the Niemen Culture. Sprawozdania Archeologiczne 58:2006 pp. 355-375.

Dear Professor Michał Kobusiewicz, thank You very much for this suggestion. Of course we will take it into a consideration during our studies.