Braathen Dendrokronologiska Undersökningar
Lunnevägen 2, SE-46144 Trollhättan, Sweden
Bringes in Norrlanda, Gotland
On the farm Bringes in the parish of Norrlanda, about 7 km from the east coast and about 2 km west of the church the ruin of a medieval two storeyed stone building is situated. As vernacular stone buildings in the rural and forested districts are rare, persons interested in history have been looking for answers to why the building was erected in stone and for what purpose it was erected.
Dating of the building may increase the possibility of more information to research in history.
A short cant timber with square cross section, a fire damaged stump from an outside gallery in the western facade gave the year 1187 for the outermost annual ring. The timber lacks waney edge. In the vault room on the ground floor two tie beams still remain under the vaulted ceiling. They are contemporary with the erection of the house. The northern beam has 167 annual rings and the southern beam has 222. The southern one has waney edge ( = the surface of the annual ring close to the bark) and therefore is of interest to examine. The variation in the growth of the annual rings is so weak that dating has not been possible. Some of the annual rings have a width of 0.05 mm. These can only be distinguished by means of microscope. Computer treatment of data from the 70 oldest annual rings give one singular peak of correlation with a reference chronology but the younger annual rings need to be moved one step forward in time on the time scale to get a positive correlation. When the ring width in pine is narrow as in this case 0.05 - 0.30 mm one or another ring may be only partly developed and by chance is missing in the sample. If this has happened in our case the outermost annual ring was built in 1232 and the building was erected in 1233 or soon thereafter.
The northern beam gives one of many examples that one has to be extremely careful when trying to infer on the age of an examined object only by receiving dating from a table where one single sample is selected. The outermost annual ring is dated 1139 and the innermost annual ring 973. Solely from these data one might suspect that this beam would originate from an earlier building but that is not the case. The innermost annual rings are developed normally up to a point where the sequence faces a peak of growth in the annual rings. This is characteristic when forest fire has passed over an area. After a fire the soil receives fertilizer from the ashes and for 3 - 5 years the trees increase their growth considerably until the fertilizing stuff is leached away. In our case the peak of growth was followed by very weak growth or 0.1 - 0.2 mm/year. The difference of 92 years between 1232 and 1139 corresponds to that 1 - 3 cm of wood has been cut off when the beam was shaped. An extrapolation from available data results in that 1.7 cm of wood has been cut away.
In the south-eastern part of the ruin is a fire place which has been put in place later. Two embedded re-cut timbers of pinewood at the fire place have waney edge, where the outermost annual ring is dated 1625. A dating of a piece of wood of this kind may seem to be unimportant but may possibly be of use in building history.