Svartifoss

The black waterfall, named for the dark lava columns that ring it, a natural amphitheatre of columnar basalt fifteen to twenty metres high and thirty wide on the southern edge of the Skaftafell plateau. The mostly hexagonal columns carry regular horizontal grooves five to twenty centimetres apart, each one recording a stage in the fracture as the lava cooled and shrank. New sections break off at the base faster than the falling water can wear their edges down, which is why the rocks below are so sharp. These columns are the model behind Hallgrímskirkja and the National Theatre.