Over the millenniums the water of the Bletterbach stream has cut a gash in the mountainside as it descends from the Corno Bianco/Weisshorn mountain (7,602 ft/2,317m). The gorge measures 8 kilometres in length and up to 400 metres deep and 400 metres wide.
A part of the gorge with a geological theme trail is accessible to walkers. Guided tours are available, though visitors can also follow the trail alone obtaining their information from the numerous information boards along the way. They describe the history of the earth in this part of South Tyrol in an easily comprehensible but scientifically well-founded manner, leading walkers through millions of years of geological history and explaining how the Dolomite landscape was formed. The gorge is rich in fossils and saurian footprints, a selection of which are on display in the Geomuseum in Redagno/Radein.