Ivrea Morainic Amphitheatre

The Ivrea Morainic Amphitheatre (sometimes abbreviated as AMI) is a moraine relief of glacial origin located in the Canavese region. Administratively, it encompasses the metropolitan city of Turin and, more marginally, the province of Biella and the province of Vercelli. It dates back to the Quaternary period and was created by the transport of sediment to the Po Valley that took place during the glaciations by the great glacier that ran through the Dora Baltea valley. With an area of more than 500 km², it is one of the best-preserved geomorphological units of this type in the world. As an extension, it is surpassed in Italy only by the similar formation surrounding Lake Garda. The name amphitheater, usually given to these geomorphological structures, refers to their characteristic elliptical shape that is noticeable when it is shown as a plan on a map.

Throughout the area concerned, the various glacial pulsations that have produced impressive moraine accumulations over time are clearly evident. Of particular note among these is the left lateral moraine of the ancient glacier, known as the Serra di Ivrea: this is the largest formation of its kind existing in Europe. The Serra originates on the southern slopes of Mombarone (2371 m a.s.l.) and heads in an almost straight path southeastward for almost 20 km, then fraying into the heights surrounding Lake Viverone. It consists of a series of sub-parallel ridges, the highest of which reaches a maximum elevation difference of 600 meters from the AMI inner plain in the Andrate area. This elevation difference gradually decreases eastward until it reaches about 250 meters near Zimone.

Its right-hand counterpart, less regular in shape, is represented by the elevations located between Bairo and the outlet of the Chiusella stream on the plain. Here, as well, the highest altitudes are reached in the weld zone with the alpine chain (about 800 m a.s.l. near Brosso); between Strambinello and Baldissero Canavese the continuity of the hill chain is then interrupted by the gorge by which the Chiusella veers eastward heading toward the confluence with the Dora Baltea.

The frontal moraine, on the other hand, consists of a succession of hills that extend between Agliè and Viverone and are interrupted between Mazzè and Villareggia by the gap opened by the Dora Baltea. The high point of this moraine sector is Bric Vignadoma (520 m a.s.l.), near Vialfrè.

Within the amphitheater lies the vast flat area, whose elevation is generally between 210 and 270 m above sea level, in which numerous population centers, including the city of Ivrea, are located. The continuity of this plain is interrupted here and there by isolated reliefs and a few minor hilly cordons; one of these defines within it the Small Morainic Amphitheater, centered on the towns of Strambino and Scarmagno. The catchment area of Lake Viverone is also defined not only by the outer moraine circle of the AMI, but also by smaller internal deposits; the municipalities in this area have grouped into the hill community around the lake.

According to the SOIUSA orographic classification, the elevations located on the hydrographic right of the Dora belong to the Graian Alps and, more specifically, to the Rosa dei Banchi alpine group, while the moraines on the hydrographic left are part of the Biellese Alps and therefore also of the Pennine Alps.

The AMI is traversed in a north-south direction by the Dora Baltea, which also collects water from the Chiusella and other minor streams. Some of the water carried by the Dora is collected by the Naviglio di Ivrea and, after providing water for Vercelli's rice-growing industry, is diverted to the Sesia basin. The outer slopes of the hills that make up the AMI are tributaries of the Orco (to the west) and Elvo (and east) basins.

Nestled among the various moraine cordons that make up the amphitheater are numerous lakes whose formation is closely related to the geological history of the AMI. While Lake Viverone is quite large (in terms of surface area it is the third largest body of water in Piedmont) the others are small to medium in size. Just north of Ivrea are located the 5 lakes, the largest of which is Sirio; the right side moraine, on the other hand, hosts Alice Lake and Meugliano Lake, while between the hills that make up the frontal moraine are Candia Lake and the smaller ones of Maglione and Moncrivello.