West of Mt. Krafla are trails of explosive craters, including two 500 m wide craters in the oldest row. Víti and the largest craters in Hveragil are more than 300 m in diameter. During an eruption which occurred towards the end of the last ice age, a large section of Mt. Krafla was blasted off the mountain. Later the craters were filled but their outlines are clearly visible. In the course of the eruptions, light coloured pumice mixed with basaltic tephra and scoria was extruded. During the eruption in Hveragil, about 10,000 years ago, the eruption column was carried to the southwest and a pumice layer from it is found on the slopes of Mt. Dalfjall. Víti erupted as the Mývatn fires began in the spring of 1724. The pumice and scoria which was expelled during the initial phase of the eruption, can be found at the base of a 10 m thick layer of mud and rock debris in the southern rim of the crater. This eruptive material originated from mud and steam eruptions due to boiling of the geothermal system. The Víti tephra may be traced to the south beyond the road east of Námaskarð where it is 1 cm thick.