The Morainic Amphitheater of Ivrea is the winegrowing heart of the Canavese area. Lands of glacial origin are ideal for winegrowing. The microclimate is mild, protected by the hills and balanced by the presence of many lakes. Furthermore, the area benefits from the constant breeze blowing from the nearby Valle d’Aosta Alps.
The Morainic Amphitheater of Ivrea (usually abbreviated in Italian as AMI) is a morainic hill of glacial origin located in the Canavese area. From the administrative point of view, it extends from the province of Turin to the provinces of Biella and Vercelli. The AMI dates back to the Quaternary period and was formed by the deposits transported towards the Po Valley during the glaciations in the Dora Baltea basin. With a surface of over 500 km², it is one of the world’s best-preserved geomorphological units of this kind. It is Italy’s second biggest geological formation after the one surrounding the Garda Lake. The name “amphitheater”, usually given to this kind of geomorphological complex, refers to its characteristic semicircular shape, which is evident when shown on a map.
The glacial pulses, which have produced impressive morainic deposits over time, are very evident in the area involved. Among them is the left lateral moraine of the ancient glacier, known as Serra of Ivrea: it is Europe’s largest formation of that kind. The Serra extends from the southern slopes of Mount Mombarone (2371 m. above sea level ) to the south-east for about 20 kilometers and then frays into a fringe in the hills surrounding the Viverone Lake. It consists of a series of sub-parallel crests, with a sharp difference of level of 600 m between the highest relief and the AMI’s flat internal plain in the Andrate area. Such difference of level decreases gradually down to about 250 m. near Zimone.
The rocky substratum on which the Morainic Amphitheater of Ivrea is situated can be distinguished into three geologic units, separated by the Insubric line. Such tectonics discontinuity is divided into two faults running parallel to each other in the Biella and Canavese area: the Internal Canavese Line, to the south, and the External Canavese Line, to the north. In the AMI area, to the north of the External Canavese Line, is the Sesia Lanzo Zone, consisting mostly of mica schists and rocks, which underwent deep metamorphism. The Zone comprises the Mombarone, to the hydrographic left side, and Mount Gregorio on the Dora’s opposite side. In between the two Canavese Lines is the Canavese area, an area geologically characterized by lithologic heterogeneity and emerging near the Montalto Dora and the five lakes. Instead, to the south of the Internal Canavese Line, the rocky substratum belongs to the Ivrea Verbano Zone. Among the types of rocks that form this geologic unit in the AMI area, basic granulite is rarely found, as these rocks, according to geologic studies, originated from the deepest portions of the continental crust, near the sub-boundary of the earth’s mantle. Part of the city of Ivrea was built upon this rocky substratum, which clearly emerges near the sanctuary of Mount Stella.
According to geologists, during the final phase of the Pliocene, the geologic period preceding the formation of the Morainic Amphitheater in the Canavese area, the sea, which back then extended over the Po basin and into the Aosta and Orco valleys, was gradually filled up with sediments derived from the erosion of the Alpine chain.
Instead, the AMI formed during the Pleistocene when, owing to the drop in average temperatures and increased rainfall over the Alps, an enormous mass of ice, which was brought downhill from the big glaciers, began to build up. In particular, the floor of today’s Aosta Valley was, in successive stages, completely filled up by the Balteo Glacier which, just like today’s Dora Baltea river, crossed the Canavese plain and then fanned out stretching, during the most intense glaciation phases, as far as the current towns of Caluso and Agliè.
The glacial epochs of the Pleistocene were traditionally divided into Mindel, Riss and Würm. In the past, the three main morainic rings, which form the AMI, were known by the name of these sub-periods, whose temporal subdivision was mostly based on the studies on the effects of glaciation to the north of the Alps. Later on, this classification was no longer considered to be accurate enough to describe the geologic evolution of the basins situated to the south of the Alpine chain. Therefore, the current subdivision of the morainic rings is the one shown in the table that follows (based on the Geologic Chart of the Morainic Amphitheater of Serra):
The deposits left by the oldest of the three major glacial pulses (San Michele – Borgo group) are the outermost ones and are more easily spotted on the AMI’s left side, in the Biella area of the Serra. The frontal moraine and most of the right one were covered with drift left during the following phase, which began about 700.000 years ago. During this period, the best preserved of the three morainic rings, the Serra d’Ivrea group, was deposited. In addition to the Serra’s main body, this group includes most of the frontal moraine that we can see today (approximately the area between Moncrivello and Torre Canavese) and part of the hills located at the end of the Valchiusella valley.
The hills dating back to this glacial phase are the highest ones, because they formed when the moraines had already been deposited in that area by the previous glacial pulse. The third group of deposits, called Bollengo-Strambino (or also Bollengo-Albiano) is the youngest one and is situated within the two previous groups. It includes several lower morainic ridges and the Serretta, a low hill that parts from the Serra’s main body near Bollengo. The other glacial periods in the history of the Pleistocene have left no sedimentary record in the area, because their deposits were later covered up and/or moved by the sedimentary masses associated with the three main morainic rings.
Lands of glacial origin are ideal for winegrowing. The microclimate is mild, protected by the hills and balanced by the presence of many lakes.