In the course of these processes profound joints were created that made the development of caves and sinkholes possible. Following the miocene karstification, the ridge was buried under loose sediments. The removal of these sediments during the &lt;a href="Eemian"&gt;Riss/Würm interglacial period&lt;/a&gt; happened asymmetrical because of the mighty down-cutting of the Mur river. As a result, the eastern slope of the Buchkogel shows a concave profile. On the western side a blind valley with numerous sinkholes and little poljes was formed. The sparse creeks run through a ponor into the mountain and emerge from the Eisbründlhöhle, a small cave about 70 meters below on the eastern foot of the hill. At that sea level the Devonian rocks meet the loamy and thus water-damming sediments of the Riss terrace. The subsurface connection at the narrowest part of the hill ridge could be scientifically verified in the 1950s via dye tracing. This means that the hill has its own closed karst water system which is not connected to the Mur valley's groundwater body.