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Description: These polygonal blocks of rock are basalt – a fine-grained, mafic igneous rock resulting from cooling of lava at, or near, the surface of Earth. Polygonal columns of basalt, often 3, 4, 5 or 6-sided, formed due to differential cooling of a lava flow from the top and bottom toward the center of mass. As lava cools, it contracts, and the resulting volume reduction causes regular fractures to form that propagate toward the center of the flow as it cools forming ‘columns’. Columnar basalt can be observed in many locations along the North Mountain Basalt of Nova Scotia, with some of the most striking examples being found in the Digby area.