High Route 1 — Stage 1: Donnas → Perloz

Ciencias de la Tierra

Geología y paisaje

This stage crosses the southern margin of the Penninic Zone, where micaschists and augen gneiss of the Hercynian crystalline basement (~300 Ma) outcrop on upper slopes. Below 800 m, Mesozoic limestones and calcschists of the lower Penninic stack dominate, often masked by eluvial-colluvial cover. The terraced slopes of Donnas and Pont-Saint-Martin display paleosols on carbonate bedrock with post-glacial differential erosion. Along the Dora Baltea, Würmian fluvial terraces carry sub-rounded pebbles of gneiss and marble. Pleistocene moraines are sparse in the valley floor but documented on regional maps. The lithological transition toward Perloz marks entry into the Austroalpine metamorphic domain of Mont Mars, with mica schists and quartzites.