The mountain stretch of the Tagliamento testifies how variable and versatile "our" river course has been over the millions of years (even when no one had yet given it a name), changing route several times and leaving an indelible mark on the features of Carnia and its valleys.
The combination of fluvial actions and descents of glacial tongues which occurred over the course of geological eras, all guided by more or less erodible lithologies and still active tectonic lineaments, has been beautifully illustrated by various geosites (according to the definition of the FVG Region, these are the places that best represent the geological, tectonic, paleontological, mineropetrographic, geomorphological evolution and geological processes) accessible and easy to interpret.
For example, between Forni di Sotto and Caprizzi the Upper Tagliamento Valley tells us of a series of post-glacial landslides, which also occurred in historical times, with direct consequences on the destruction of an entire village – Borta, destroyed in 1692 – and on the formation of lakes, not all persistent over time, but which convey the idea of the dynamism and variability of a landscape wherever a river is involved.
Further downstream, in the village of Cesclans, the geosite called ‘Rupe’ exhibits the rocky content composed of tenacious conglomerates, old varicolored gravels firmly cemented. They are witnesses of an ancient river route abandoned by “ours” (i.e. the current one) at the end of the last glaciation and headed south, towards the plain that today hosts Lake Cavazzo. The same rocks are also found upstream up to Ampezzo, within a long series of relatively low and flat hills: they clearly highlight previous paleo-routes of the Tagliamento even in places now crossed by other watercourses. The discovery of such well-preserved remains of a paleovalley is a rather rare case for the southern Alps!
Walking among the Tilaventine geosites of Carnia takes us back in our imagination to a lost world of a few million, thousands or even just hundreds of years ago, observing a landscape and geography that are sometimes very different from the current ones, thanks to pre and post river digressions glacials of this noble river.