How Are Columnar Basalt Formed?

The shape, formation and texture of a basalt is usually determined by the way it erupted and also where it erupted in terms of if it erupted in the sea, in an volatile cinder eruption or as creeping pahoehoe lava flows, the standard image of Hawaiian basalt eruptions.

The Columnar Basalt is produced during the period of the cooling of the thick lava flow, which forms contractional joints or fractures. The flow usually shrinks in the vertical measurement without fracturing, and cannot manage to sink in horizontal direction until the cracks are formed. This exclusive fracture networks results into the columnar formation. Some of the famous columnar basalts formed are Giant's Causeway, Devil's Postpile, Narooma Basalt (Narooma, New South Wales, Australia), Samson's ribs and Isle of Staffa, Inner Hebrides