To be inscribed on the UNESCO World Heritage List, UNESCO World Heritage properties must be of Outstanding Universal Value and meet at least one of ten selection criteria. The Swiss Tectonic Arena Sardona meets criterion VIII for its inscription.
Criterion (viii): Earth’s history, geological and geomorphic features and processes: The Swiss Tectonic Arena Sardona provides an exceptional display of mountains building and has been recognised as a key site for geological sciences since the 18th century. The clear exposure of the Glarus Overthrust is a key, but not the only significant, feature. The exposures of the rocks below and above this feature are visible in three dimensions and, taken together, have made substantial contributions to the understanding of mountain building. Its geological features can be readily appreciated by all visitors. The property can be differentiated from other similar sites by the combination of the clear exposure of the phenomenon in a mountain setting, its history of study, and its ongoing contribution to geological sciences.
Integrity: The property contains the full range of tectonic features necessary to display the phenomenon of mountain building. Key attributes of the site include the Glarus Overthrust and the associated folded and faulted geological exposures above and below it. Other key attributes of the property are the accessibility of the features in three dimensions, and access to the thrust surface of the Glarus Overthrust. Associated intangible values relate to the importance of the property as a formative site for the geological sciences; and the features that were part of these studies remain visible and in good condition in the present day.
You can find further information at whc.unseco.org.