The Ögmundarhraun lava flow formed in an eruption in the year 1151 AD. In that year a 25 km long fissure opend obliquely across the Reykjanes peninsula. Lava flowed from the fissure apart from its central part forming one major flow to the south (Ögmundarhraun) and another to the north (Kapelluhraun). Where the Dúpavatnsleið road meets the road along the south coast are beautiful small row of craters formed in the eruption and fossilized lava cascade down the mountain slopes.
Haukur Jóhannesson, 2010