An eruptive fissure crosses the Jökulsá canyon diagonally by the Hafragilsfoss waterfall. As it erupted, one of the longest crater rows in Iceland was created, extending 70 km from Öxarfjarðarheiði in the north to Mt. Austari-Skógarmannafjöll in the south. The crater row is located in the fissure swarm of the Askja volcanic system. According to tephrochrono-logical data the eruption took place about 11,000 years ago. The crater row is discontinuous and several discrete lava flows originate from it. Randarhólar is a 4 km long section of the crater row located on the eastern bank of the Jökulsá river. The canyon exposes a cross section of Sjónnípa, one of the Randarhólar craters. The crater’s feeder dike and its interior structure is clearly visible. Geological cross sections of this kind are rare.