Sedimenti eolici, variazioni climatiche ed influenza antropica: considerazioni su alcune piane intermontane dell'Appennino Abruzzese

Abstract

In some plains and plateaux in the Abruzzese Apennines (Campo Imperatore Plain in the Gran Sasso Massif; Campo Felice Plain, in the Velino Massif; Upper Venafrana Valley in the Meta- Mainarde Massif; Upper Chiarano Valley, Polverino Plain, Antone Rotondo Plain, Stazzo Ospeduco Depression, Aremogna Plain in the Mi Greco Massif) eolian deposits, dated to the second half of the Holocene, have been found. In the same areas, eolian sediments formed during present times can be found, where unpaved roads cut silty soils, or around sites subjected to overgrazing. Human impact may produce environmental changes favourable to eolian deflation, and in general the studied eolian sediments have just been formed under deflation processes of silty soils developed in the first half of the Holocene. Deflation (more recent than 4,690±250 years B.P.) seems to be the consequence of regional environmental changes. Theoretically, such environmental changes could have been produced either by climatic variations or by human impact: the presence of eolian deposits proves that deflation processes took place, but it does not provide objective data to determine their cause. On the contrary, detailed studies on the morphology, direction, size and age of blow-out features, occurring in a small (0.5 km²) area of the Aremogna Plain, show that a notable change in the directions of the winds causing the deflation took place during the last 4-5,000 years. In the same period the landscape of the Aremogna Plain and the surrounding area did not change it is concluded that the variations of wind direction are to be attributed to climatic changes, human impact being not a cause. In the Aremogna Plain and in the Abruzzese Apennines, other proxy-data contemporary with the eolian deposits, prove that environmental changes occurred, being mostly linked to climatic variations.