Geological trail along the Val Pogallo

The geological trail, known as the ‘Linea del Pogallo’, forms a thematic extension of the more extensive ‘Via GeoAlpina’, which crosses the north-eastern part of the Geopark in seven stages.

The route follows the Sutermeister Trail and runs largely through metamorphic rocks of the geological unit known as the Strona-Ceneri zone. This zone consists of two types of paragneiss, metamorphic rocks of sedimentary origin: the Gneiss Minuti (stop 1) and the Gneiss Ceneri (stop 2), both of Cambrian age. Intercalated amongst these are lenses of orthogneiss (stop 3) derived from granites that intruded during the Ordovician. All these rocks were transformed, around 340 million years ago (Ma), by metamorphism associated with the Hercynian orogeny when they were subducted to depths of at least 20 km and subjected to temperatures exceeding 500°C. In the subsequent Permian period (270 Ma), intense magmatic activity led to the intrusion of granites into these formations, which, however, were virtually unaffected by the events that subsequently (from around 90 Ma) led to the formation of the Alps. Once past the wooden footbridge (stop 4), milonites come to the surface; these are rocks formed by friction during the movement that occurred along the Pogallo fault. On the final stretch before Pogallo, you pass through kinzigites (stop 5), which are also metamorphic rocks but do not form part of the Laghi Series; rather, they belong to the adjacent Ivrea-Verbano zone.