|Location:||A9 exit Pegnitz-Grafenwöhr, B85/B470 towards Auerbach/Grafenwöhr, turn right at kilometre 3,0 on forest road. At parking lot Alte Veste take the Habicht trail towards west for 700m.|
|As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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The Großer Lochstein (literally Big Rock with Hole) is a karst tower, a limestone tower formed by intensive karstification under sub tropic or tropic conditions. It is typical for the socalled tower karst or cockpit karst. The karstification forms cave, then they collapse, form roofless caves, valley, poljes and finally there is a connected plain with limestone towers with vertical walls. This is a sort of inverse relief to what we know in cool humid climates, well known from Aisa, but almost unknown in Germany.
Actually this tower is not a result of the recent karstification. It is a relict of an early karstification under tropic conditions. During the Lower Cretaceous (Ma) the Malm of the Frankian Jura was karstified, as it formed an island in the Cretaceous sea which covered most of central Europe. During some 40Ma the typical tower karst formed. But then the area was downlifted again, and during the Upper Cretaceous the caves and valley were covered by sea and filled with sands. In the southern part of the Frankian Jura such completely filled caves were discovered in quarries. Here, in the northern part, the sand was almost completely removed by later erosional processes. The towers were decovered and the caves opened.
Since the end of the Upper Cretaceous this area has been due to erosion continually. First the Cretaceous sediments were removed almost completely, but when the Jurassic surface reappeared it was also eroded. This changed the face of the surface and there is little left from the Cretaceous tower karst nowadays. But the area of the Veldensteiner Forst is different, the sediment cover remained very long and was eroded a very short time ago (in geologic terms) during the quarternary. And while modern erosion has begun to chnage the form of the towers, the original Cretacious karstification is still visible.
The Großer Lochstein is a 20m high cliff consisting of the typical Frankian dolomite. It is crossed by a spacious, some 10m long cave at its foot.