Glaciation and deglaciation: geomorphic signatures on morainic amphitheatres of Ivrea and Belvedere

Home : Geothematic Areas : Glaciation and deglaciation: geomorphic signatures on morainic amphitheatres of Ivrea and Belvedere

The Ivrea and Belvedere morainic amphitheatres are sites of great scientific, aesthetic and cultural value. They provide an excellent gym in science education, through the various information they provide in geologic, geomorphologic and paleoenvironmental topics, very important to reconstruct the evolution of the area.

The Ivrea Morainic Amphitheatre (IMA) is one of the largest amphitheatres of the Italian Alps and the main evidence of the Aosta Valley Glacier, built from late Lower Pleistocene to late Upper Pleistocene (900 000-20 000 years ago). It corresponds to one of the first amphitheatres studied in Italy and several publications testify to the interest from prominent Italian and foreign researchers.

The IMA extends over 500 square kilometers at the outlet of the Dora Baltea Valley. It is formed by a complex set of glacial circles, comprising frontal and lateral moraines and kame terraces. The succession of glacial sediments appears now differentiated in ten stratigraphic units, perhaps to the entire sequence of the main Quaternary Glaciations recorded, in the marine environment, by the oxygen isotopes preserved in sediments.

The IMA is characterized by a strong morphologic contrast between a wide and flat internal depression (about 200 km²) and the high moraines that surround it (about 300 km²), resulting in strong height differences (over 400 m). It was described as «il più chiaro, il più parlante, il più imponente fatto geologico dell’alta valle del Po» (GASTALDI, 1869), «forse il più grandioso degli anfiteatri glaciali d’Europa» (SACCO, 1890) and «le plus considérable des amphitéatres de la glaciation alpine» (PENCK et al., 1894), considering the large size and the tipycal features of the landforms.

The Belvedere glacier is the largest glacier in Piemonte region. It is located at the head of the Anzasca Valley, dominated by north eastern side of Monte Rosa, an alpine valley showing a strong geodynamic activity during recent years, sometimes causing also risk conditions.

The climatic context appears to play a fundamental role in enhancing the slope instability phenomena occurring at high altitude. Currently ice collapses and rock falls are increasing and consequently the surface debris cover is increasing its self too, giving the glacier the typical appearance of debris covered Glacier. On 25th August 2005 one of the major ice avalanche happened in the last hundred years in the Alps occurred, the latest event in a series that has been radically changing the Himalayan aspect of the east wall of Monte Rosa.

Image gallery (click to enlarge)

[Not a valid template]