Iceland is called 'The Land of Ice and Fire' for a good reason. The glaciers and cold climate mixed with volcanoes and geothermal activity is undeniably an interesting combination. There is seldom eruptions, but activity is going on all the time. Nature is for real up here, in all its mystery, which you will see when you travel here.
East of Reykjavik, Iceland lies the mountain, Hengill. Hengill was formed from a Palagomite tuff, it is a central volcano and has a giant magma chamber beneath it. When thick basalt lava flows cool, they form hexagonal cracks, called columnar joints. These can be found also in Ireland & Scotland.