File talk:Small mountain stream disappearing at lower slope in Stubai Alps.jpg
File renamed (originally was Ponor, Stubaier Alpen.jpg)
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The phenomenon depicted in the photograph was, according to the original file name, identified as a ponor, i.e. an entry to a cave system completely swallowing a (small) stream, typically found in regions underlain by karstified carbonate rocks.
However, if the coordinate is correct (and there is no reason to doubt that), then the photo was taken in the Stubai Alps, in the upper part of the Sulz Valley (Sulztal). This region belongs to the Central Eastern Alps and hence geologically is dominated by gneisses and schists, not by carbonate rocks, and thus is unlikely to have karst features. The reason for the stream disappearing at this point is that the underground changes there from solid rock to the debris which has accumulated at the lower slopes to form extensive screes. These screes probably have a dense framework of cavities through which the water can travel further downhill without being visible on the surface, at least as long as the water volume carried by the stream is small enough.
Hence I have renamed the file, giving it a more appropriate name not implying a karst phenomenon. Gretarsson (talk) 23:47, 13 July 2024 (UTC)
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