As you turn off Road 54 and drive less than a mile towards Gerðuberg Cliffs, you begin to see this impressive wall stretching for 1,640 feet. You will assume it is manmade. The origin of these basalt columns is volcanic. They were formed as lava cooled irregularly from top to bottom, causing fractures in the rock as it contracted. When the columns form a straight row (similar to a colonnade), the result is called columnar jointing.
