pylväkitesit

Pylväkitesit are pillar-like rock formations found in volcanic and sedimentary settings. The term is Finnish and describes vertical columns of rock that rise from cliffs or bedrock, often appearing in regular patterns.

Formation and characteristics: Pylväkitesit typically form when rocks crack and separate into vertical columns, or when lava cools and contracts to create jointed columns. The most familiar examples occur in volcanic rocks such as basalt, where the columns commonly have hexagonal cross-sections and can reach several meters in height. In sedimentary rocks, pillar-like concretions may develop around organic material or mineral-cemented elongate structures, and differential erosion can leave upright columns standing after surrounding rock wears away.

Size, shape, and distribution: Columns vary from a few centimeters to many meters tall. Cross-sections are often hexagonal but can be irregular, depending on the cooling rate, rock type, and initial jointing. Pillar formations are found in many parts of the world, with the best-known basalt examples widely referenced in geological literature.

Context and terminology: In Finnish geology, pylväkitesit is used to describe such pillar structures, particularly in contexts where columnar jointing is evident. In English-language geology, the phenomenon is more commonly described as columnar jointing or basalt columns, with well-known examples including the Giant's Causeway and Fingal's Cave. The concept illustrates how cooling, erosion, and rock properties interact to create striking vertical rock features.