pylväsmuotoja

Pylväsmuotoja, a Finnish term, translates to "columnar formations" in English. This geological phenomenon refers to naturally occurring, often vertical, rock structures that exhibit a distinctive columnar or prismatic appearance. The most common cause for the formation of such structures is the slow cooling of thick basaltic lava flows. As the lava cools, it contracts, creating a network of cracks that often form polygonal (typically hexagonal) columns. These cracks propagate through the cooling rock, resulting in the characteristic upright, pillar-like shapes.

These columnar joints are a common feature in volcanic regions worldwide. Famous examples include the Giant's Causeway in Northern Ireland, the Devil's Postpile in California, and the Svartifoss waterfall in Iceland. The size and shape of the columns can vary depending on factors such as the composition of the lava, the rate of cooling, and the thickness of the flow. While basaltic lava is the most frequent precursor, other igneous rocks and even sedimentary rocks can sometimes exhibit similar jointing patterns under specific conditions, though these are less common and may be referred to by different, more specific geological terms. The study of these formations provides insights into the cooling processes of magma and lava.