Val d’Otro

The Val d’Otro is an excellent example of a glacially formed hanging valley. It is, in fact, a secondary valley of the Valsesia – the main valley – to which it is connected via a glacial step with a height difference of around 500 metres. Indeed, just as the Otro stream is now a tributary of the Sesia, the Otro Glacier was once a tributary of the Valsesian Glacier.

During the Last Glacial Maximum (around 20,000 years ago), Valsesia was covered by a complex glacial system consisting of several glacial flows originating in the side valleys and converging into the main valley. The individual glacial flows had varying erosive capacities and intensities. The glacier originating from the Val d’Otro was smaller than the main Valsesian glacier; for this reason, the current profile of the Valsesia lies at a significantly lower altitude than that of the side valleys. Once past this rocky threshold and upon reaching Otro, the terrain gives way to much gentler slopes, which have been utilised by people to establish their settlements. The hamlets of Otro are in fact situated on what remains of an ancient glacial terrace, formed by successive processes of deposition and erosion by the glacier that once crossed the Val d’Otro.