UPPSALA, SWEDEN—Industrial-scale production of tar in the eighth-century A.D. allowed the Vikings to waterproof large numbers of ships and raid other parts of Europe, according to a report in The Guardian. Andreas Hennius of Uppsala University says that pits uncovered during a road construction project and dated to between A.D. 680 and 900 were not used for making charcoal, as had been previously thought, but instead for tar manufacture. The pits, discovered near pine forests, were filled with pine wood, covered with turf, and set on fire. Each production cycle could have resulted in about 80 gallons of tar, Hennius said. Smaller tar kilns dating to between A.D. 100 and 400 have also been found. For more, go to “The First Vikings.”