Beginning on June 8, 1783, the multi-year eruption of the volcanic system including Grímsvötn and Þórðarhyrna (sometimes referred to in Icelandic as the Skaftáreldur, Skaftá Fires) filled the river valley with lava, including a gorge thought to have been 200 meters deep, diverting its flow into the multiple shallow channels that now characterize its course.