Columns can form in a variety of patterns, mainly hexagonal (but can be found with anywhere from 4-8 sides). They can vary in size from only a few centimeters to meters across. They form when a thick body of cooling magma starts to contract and cracks begin to form. These cracks start at/near what is called the “cooling surface”, which might be the top or bottom (or sides) of the lava flow, magmatic intrusion or ash deposit. The cracks propagate into the cooling material making (upon close examination) stacks of plates that form the columns. The plates are usually aligned parallel to the flow surface, while the columns form perpendicular to the cooling surface. If you look closely at a column, you will see feather-like fracture patterns called “pluma” that represent the cracking of the cooling material in response to the strain that the material is feeling as it contracts.