Basalt Column

Basalt columns are impressive geological formations formed by the cooling and shrinking of lava. They have a hexagonal shape and often form regular patterns reminiscent of natural stone walls. These fascinating structures are a typical feature of basaltic rocks and can be observed in various places around the world, including La Palma, the Giant's Causeway in Ireland, and the columns of Svartifoss in Iceland [2External link].

Basalt is a basic effusive rock composed primarily of a mixture of calcium-iron-magnesium silicates (pyroxenes), calcium- and sodium-rich feldspar (plagioclase), and often olivine [1External link]. It is the volcanic equivalent of gabbro, a slowly crystallizing plutonite deep in the Earth's crust with a similar chemical composition to basalt.

The formation of basalt columns is closely related to the cooling of lava. During the solidification process, contractions occur, leading to the formation of cracks and fissures. These cracks propagate perpendicular to the interfaces of the lava flows and eventually form the characteristic hexagonal basalt columns. The columns are usually contiguous and often range in diameter from 10 cm to 1 m, although larger or smaller sized columns may also occur [5External link].

The exact formation of basalt columns can be studied by physical means. Factors such as thermal contraction, fluid behavior, and crystallization processes play a role [2External link]. These processes lead to the formation of the regular hexagonal patterns that we can admire in basalt columns.

However, the use of basalt is not limited to geological phenomena. Basalt is also used as a building material, especially for paving stones. These stones are extremely durable due to the hardness and durability of basalt and are often used in pedestrian areas and other high-traffic areas. The dark color of basalt also gives the paving stones an appealing aesthetic [6External link].

Location of the basalt columns near the village of Themar

Image: Thomas Voigt