Merkjárfoss / Gluggafoss
The Merkjá River has several beautiful waterfalls, but the most outstanding is Gluggafoss or Window Falls. (also known as Merkjárfoss) The upper half of the cliff is palagonite or tuff rock and the lower ledge is basalt. The river has formed tunnels and grooves through the soft rock and a series of 'windows' in the tunnels, thereby earning the name 'Gluggafoss'. At the very top of the falls, the river passes under a stone arch. As the rock is rather soft, the waterfall has changed over time.