Eldgjá canyon was formed in an eruption in the year 939 – 940 and the lava it produced is typical for the Katla Volcanic System.  It is a 75 km long crack, up to 600 meters wide and 200 meters deep – the longest volcanic canyon in the world.  The eruption produced about 4.5 km3 of aerosols and 18 to 19 km3 of lava which spread over 800 km2 – making it the largest lava field in historic times.

Ófærufoss is an interesting waterfall that was formed in the eruption. The waterfalls are two and there used to be a very spectacular stone arch across the lower one. It was very popular to walk over this stone bridge but, alas, in spring floods in 1993 the stone arch collapsed.