Where did the immense glacier that spilled out onto the plain, creating the Ivrea Morainic Amphitheater, originate? Its colossal catchment basin largely coincides with what is today an entire region: the Aosta Valley. It extends across 3,355 square kilometres along the valley carved by the Dora Baltea over 90 kilometres (the final 10 in Piedmontese territory), and includes some thirty tributary valleys and side valleys. Among the source areas of the Balteo Glacier are some of the greatest mountain massifs in Europe: Mont Blanc, Monte Rosa, the Matterhorn, and Gran Paradiso. Their height and relative proximity to the plain explain the enormous “energy” of the Balteo, which, between 900,000 and 11,500 years ago, over the course of at least nine successive glaciations, sculpted the entire Ivrea Morainic Amphitheater.
Nothing withstood the force of millions upon millions of cubic metres of moving ice: this solid river, reaching depths of up to 700 metres, dragged along the immense variety of rocks it encountered on its path and deposited enormous erratic boulders — still clearly visible today — up to 30 kilometres from their point of origin, generating pressure sufficient to erode even the extremely hard bedrock that forms the Colli d’Ivrea. A titanic undertaking that, after decades of study, we are finally able to understand and reconstruct.
