bletterbach gorge in the dolomites in italy

butterloch bletterbach gorge radein redagno aldein aldino ueberetsch unterland oltradige bassa atesina south tyrol trentino alto adige italy lead zinc mineralisation cephalopod bank west waterfall carbonaceous siltstone lenses coal bituminous sandstone dolomitic limestone galena sphalerite carbonate concretions dolomites alps italian georg george old mining hiking north valley