Glarus Thrust

The Glarus thrust is a major thrust fault in the Swiss Alps, cropping out across the cantons of Glarus, St. Gallen and Graubunden, where its near-horizontal orientation and the region's steep relief expose it over an unusually wide area. Along it the Helvetic nappes were pushed more than 100 kilometers northward over the external Aarmassif and the Infrahelvetic complex, bringing older Permo-Triassic rock into direct contact above much younger Jurassic, Cretaceous and Paleogene strata. Its most famous outcrops lie near the town of Glarus and at the Tschingelhorner cliff between Elm and Flims, where the thrust plane is pierced by the Martinsloch, a triangular hole roughly 6 by 18 meters wide; in 2008 the surrounding area was inscribed as a UNESCO World Heritage Site, the Swiss Tectonic Arena Sardona, covering 32,850 hectares across 19 communities in recognition of its exceptional exposure of mountain-building through continental collision. The thrust's visibility and accessibility made it historically important to developing the modern understanding of how thrust faults and mountain belts form. This entity documents the Glarus thrust specifically as a geological formation.