Diablak is a not very prominent but geologically very interesting summit in the northern part of the Kaczawskie Foothills, approximately 1.5 km south of Wilków. The summit reaches an elevation of 390 metres above sea level. To the south, it transitions into a narrow, rocky ridge that descends steeply into the Bystrzyk (Wilcza) valley.
The elevation is composed of basalt, which occurs in the form of a vertical vein with a width of several meters and a length of about 100 metres. It penetrated through Triassic and Cretaceous sandstones, which are much less resistant to weathering than basalt. Therefore, the formation of a ridge occurred, undercut with cliffs reaching heights of up to 20 metres. The cooling of basaltic lava led to the formation of columnar jointing, with columns arranged in various orientations, ranging from vertical to inclined at an angle of about 45°.
A geological curiosity is a large oval sandstone xenolith, about 1.5 metres in length, embedded in the lava. It is exposed in a small, old excavation undercutting the southern end of the ridge and stands out against the dark basalt with its light colour. A xenolith, that is a fragment of rock through which basaltic lava penetrated, detached from the wall of a volcanic chimney, exhibits columnar jointing, with the columns having only a few centimetrrs in diameter. Places of this type are very rare in the Sudetes (the nearest one is located near the town of Łupki in the Izera Foothills, and others are known from the Czech part of the Western Sudetes).
Description: Piotr Migoń
