Every horizon has a symbol that makes it unique, recognisable above all others. The symbol of the Ivrea Morainic Amphitheater is the imposing and regular perfection of the Serra. Widely admired and described as far back as 1909 by Penck & Brückner as “the greatest moraine in the Alps,” it is a textbook example of glacial sedimentation that has struck researchers from around the world with its scale and exceptional regularity. Technically, this straight ridge, extending for 21 kilometres and rising to 690 metres above the valley floor, is the left lateral moraine of the Balteo Glacier.
As is almost always the case with moraines — the deposits of rock and debris accumulated by a glacier during its advance — the Serra has a steeper inner face, while the outer slope descends more gently toward the plain. Its crest, which from a distance appears to have been drawn with a ruler, is in fact made up of seven parallel moraine ridges that slope gently downward at an average gradient of 2.75%, forming what amounts to an immense wall separating the Canavese from the Biellese. One curiosity: this is not the only Serra. Between Andrate and Bollengo there is also a Piccola Serra, which, joining the frontal moraine of Strambino and the right lateral moraine of Parella, forms an “amphitheater within the Amphitheater.”
