Basalt fissure

The Basalt Spalte of Tieschen lies in the rolling hills of south-eastern Styria. It sits on a private plot near the hamlet of Pichla, roughly 361 metres above sea level. A short walk north-west brings the visitor to the summit of the extinct Königsberg volcano, 462 metres high. To the west, the village of Tieschen sits at 260 metres, its farmhouses and church spire visible across the fields. The feature itself is a long, narrow crack in the ground where molten rock once forced its way through older layers. The surrounding farmland is quiet, broken only by the occasional tractor.

The Spalte is a relic of eruptions that took place about sixteen million years ago. Thin lava streams cooled quickly at the surface, stacking up into thick basalt columns. Over time these columns were quarried for road metal early in the twentieth century, leaving the deep, straight trench we see today. In the rock walls small drill holes mark where charges were placed. A notice points out a red xenolith embedded in the basalt, a piece of the Earth’s crust carried up by the magma.

Visitors follow a narrow path down into the trench, where the columns stand like organ pipes on either side. The walls rise three or four metres, their grey surfaces patterned with horizontal cracks. Above, the sky is framed by beech and oak trees whose roots grip the rim. A short scramble brings the walker to the xenolith, a rust-coloured block no larger than a fist, set into the rock. From the trench floor the Königsberg ridge looms close, its gentle slopes covered in vineyards and meadows.