Origin of Evolved Rocks in the Hrúthálsar–Eggert Central Volcano Herðubreiðarfjöll on the north-lobe of the Askja fissure swarm is a cluster of three hyaloclastite mountains formed during the last glaciation with a combined volume of about 10 km 3.
Herðubreiðarfjöll eru klasi þriggja móbergsfjalla frá síðasta kuldaskeiði ísaldar norðanvert á sprungusveimi Öskju, samtals um 10 km 3.