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

A study of the Ivrea and Belvedere morainic amphitheatres is included in the Project "Proactive management of geological heritage in the Piedmont Region: innovative methods and functional guidelines for promoting knowledge and supporting geoconservation activities (PROGEO-Piemonte - coord. M. Giardino)" proposed by the Earth Sciences Department of Turin. This multidisciplinary research aims to achieve a new conceptual and operational discipline in the management of the geological heritage of the Piemonte Region by means of the development of techniques for recognizing and managing its rich geodiversity at the local and regional scale. The Ivrea Morainic Amphitheatre (IMA) is the main product of the Aosta Valley glacialism at the outlet of the Dora Baltea Valley. It is one of the widest (505 km2) amphitheatres of the Italian Alps and the first to be studied (since 1844). The IMA consists of a branched complex of lateral and end moraines and kame terraces, dated from the end of the Early Pleistocene to the end of the Late Pleistocene (900÷20 ky BP). This succession is partible into ten stratigraphic units, potentially correlable to the whole sequence of the main Quaternary glaciations registered in the marine oxygen isotope stratigraphy. The IMA shows remarkable evidence of the glacial sedimentation and erosion: above all the Serra d'Ivrea lateral moraine and the Colli d'Ivrea bedrock outcrop area. The present Belvedere Glacier (9 km2) is the biggest of the Piedmont, placed below the eastern face of the Monte Rosa in the uppermost Anzasca Valley. This debris covered glacier is well-known because of its supraglacial "ephemeral lake", but it is also notable for the Holocene morainic apparate essentially referable to the Little Ice Age. The following scientific research actions will be developed with the aim to improve the already available data: 1) Surveys about sedimentologic, stratigraphical and morphological features of the Serra d'Ivrea moraine. 2) Investigation of the relations between glacial activity and bedrock features responsible for the modelling of the Colli d'Ivrea subglacial landforms. 3) Climatic significance of the Lateglacial-Holocene sequences of the Terre Ballerine and Tomalino peaty records in the Colli d'Ivrea sector. 4) Stratigraphy of the Late Pleistocene sequence of the Andrate glaciolacustrine plain. 5) Reconstruction of the T. Chiusella fluvial deviations related to the IMA right lateral sector edification. 6) Geological study of the gold placers and the ancient mines distributed at the IMA outer edge, including the Bessa Roman aurifodinae. 7) Survey of the IMA erratic blocks, according to the Piedmont regional law about the protection of erratics. 8) Research on the Holocene climatic changes derived from the stratigraphy of the Belvedere morainic complex. Research methods will consist of geological survey, photointerpretation and borehole execution, supported by radiocarbon dating, pedological, petrographic and palinological analyses and SEM-EDS gold microanalyses. The IMA geomorphologic exemplarity makes it excellent for scientific education, mainly geologic, geomorphologic and palaeoclimatic. In spite of its remarkable human settlement (93 communes), the IMA preserves wide expanse of country and woody land. The soil protection and the agricultural and natural landscape preservation have to be supported by the diffusion of a scientific knowledge of the territory. Actually a 2% of this valuable land is under the protection of two parks: the Bessa and Baragge Regional Park at the eastern edge of the IMA and the Candia Lake Provincial Park into its internal depression. Also the suggestion of further parks and geosites must be documented and well-founded. So an important aim of the project is the popularization of the results by a coordinate output of brochures, posters and geologic itineraries books, as well as lectures, workshop and short courses for teachers and naturalist guides.