Roofless Caves, a Polygenetic Status of Cave Development with Special References to Cave Regions in the Eastern Calcareous Alps in Salzburg and Central Alps, Austria

Povzetek

O pojavu brezstropih jam je že zgodaj poročal B. Dawkins (1874). F. Kraus je ugotovil, da so take jame stopnja v razvoju od normalnih jam do vrtač in sotesk, iz katerih kasneje nastanejo normalne doline. Kot primer navaja Rakov Škocjan in še posebej jamo Lončarevec pri Postojni. V Alpah so pleistocenski ledeniki zniževali površje in odprle so se jame. Ponekod je danes veliko kratkih jam - ostankov nekdanjih sistemov. Značilne so za “nivo jamskih razvalin” (Höhlenruinen-Nivo) na planotah, kot so Steinernes Meer, Hagengebirge, Tennengebirge, v višinah 2 000 - 2 300 m. Avtor podrobneje obravnava primere iz salzburških Apneniških Alp, področji Hennenkopf in Rotwandl v pogorju Steinernes Meer, Sondkar v pogorju Tennengebirge in Hochtor v Centralnih Alpah (Visoke Ture).

The phenomenon of roofless caves was reported early by Boyd Dawkins (1874). Franz Kraus found that roof collapses are the first steps in the development from a normal subterranean cave to dolines and to a gorge and to normal valley. As an example he showed Rakov Škocjan and specially “Lončarevec Cave” near Postojna. Karst in alpine regions is often dominated by glacier erosion. The ice flow of Pleistocene glaciers carved the plateau surfaces. Thus cave systems opened. In some areas there are a lot of short caves as parts of a former cave system. They characterise the “cave-ruin-niveau” (Höhlenruinen-Niveau) on plateaus such as Steinernes Meer, Hagengebirge, Tennengebirge, in an altitude of 2000-2300m. Special reference is given to the Salzburg Calcareous Alps, including Hennenkopf and the Rotwandl region in the massif of Steinernes Meer, the region of Sandkar in the Tennengebirge and of Hochtor in the Central Alps (Hohe Tauern).