Tar truth revealed by Viking Age finds

Words about words


Photos: Lindeblad et.al.
Tar pit and schematic drawing of its function (Legend in Swedish: MÖH means “elevation in meters” and MOT N means “to the north”).

Asker, Norway

Tar is a thick, dark, flammable liquid used in road building and for coating and preserving wood, made from the destructive distillation of organic substances. Today, there are two main types of tar, depending on the substance from which it is made. In northern Europe, “tar” refers to a viscous liquid derived from the controlled combustion of wood. 

The earliest records of its being made are Scandinavian, dating from around 400 A.D., and include mention of the Old Norse word tjara (tjære in modern Norwegian). Around 1665, a method for producing tar from coal was discovered. It was designated “coal tar” to distinguish it from the older “wood tar”, so today “tar” principally means “coal tar” in English, French, and German.

Tarring, the application of wood tar to wood, is a boatbuilding technology that helped trigger the Viking Age (793-1066). As mentioned in the Erik den Rødes Saga (Saga of Erik the Red), tarring of the hulls of Viking longships kept the destructive shipworm (Toredo Naualis mollusk) at bay, which enabled the long voyages of the Vikings. The wonderfully preserved Oseberg Ship (built in 820 and discovered in a burial mound in 1904, now on display in the Viking Museum in Oslo) is evidence of how well the tarring worked. 

But how and where the tars used to preserve it and other longships were made remained unknown. However, as reported in the October 2018 edition of the scientific journal Antiquity (Further reading), historical coincidence suggests that in the eighth century (when sails arrived in Scandinavia and the Oseberg ship was built), the improvement in nautical technology afforded by tarring triggered an upswing in longship building that in turn expanded the demand for tar. That led to the building of tar pits into slopes throughout Scandinavia.

Further reading:

Viking Age tar production and outland exploitation, by Andreas Hennius, Antiquity, Vol. 92, issue 365, Oct. 2018, pp. 1349-1361: doi.org/10.15184/aqy.2018.22

This article originally appeared in the April 17, 2020, issue of The Norwegian American.

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M. Michael Brady

M. Michael Brady was born, raised, and educated as a scientist in the United States. After relocating to the Oslo area, he turned to writing and translating. In Norway, he is now classified as a bilingual dual national.