Analysis of the geoenvironmental conditions as morphological evolution factors of the sand-clay series of the Tiberine valley and of the Dunarobba forest preservation

The Tiberine Valley was formed during pliocenic period after a prevailingly tensile tectonic activity and is now filled up by alluvial plio-pleistocenic deposits (lacustine and palustrine). During upper Pleistoceneand Holocene erosional phenomena led to the present morphological setting represented by hilly landscape. The Tiberine deposits are characterized by sediments whose heterogeneity, typical of fluvial environments, is given by lateral and vertical facies heteropies (clays, sands and conglomerates); they are sorrounded by limestone and marly limestone whose permeability is very high as a consequences of the dense network of joints and karstic phenomena. In such sistems, given by rock masses having different extension and permeability, hydraulic regimes developed since its formation where preferntial drainage pathways, fed both by the surficial and deep circulation waters, interfere with liquid phases of finer sediments. The research's principal aim is the definition of the geological, hydrogeological, geophysical and geochemical processes which allowed the preservation of the vegetable matter inside the Tiberine Valley. The definition of the processes which led to the lignification of coevi deposits is important as a term of comparison and in order to better interpret the whole environmental evolution.