hexagonal columnar joined basalt cross-section view in studlagil canyon (the basalt canyon), iceland

basalt brown canyon cliff closeup column columnar cross east europe formation frozen geology geometric geometry gorge hexagon hexagonal iceland icelandic joined jokla jokuldalur landmark landscape lava magma mountain natural nature pattern pillar precipice ravine river riverbank rock scenery shape stone studlagil surface texture tourism travel valley vertical view volcanic wall cross-section iceland