Marmore Falls has a very ancient natural history. This history is strictly linked to the geological vicissitudes that the territory suffered during the last 500.000 years and dictated the conditions so that the Velino river at a certain point joined with the Nera River in the area known today as Marmore.
The Marmore Waterfall is an important regulation axis of superficial water drainage over a wide area, in a hydrological point of view it meets two great depressions: the Rieti and the Tiber basins.
But it hasn’t always been in this way. These two areas, known in geological terms as mountain basins are of tectonic origins and strictly linked to the elevation of the Apennine mountain ranges. The Velino river, influenced by these events which caused the geological evolution of the Rieti basin, interested more and more the northern area of the basin. Here, the faults created a narrow way between the mountainous ranges, known today as “Piano di Canale”.
A research published in a recent book points out that about 100.000 years ago, this opening allowed the Velino river to break in the North to mix its water with the Nera river that, in the meanwhile, followed the phases of the geological evolution of the Ternanan basin, the southern area of the Tiber basin. In that time the Nera river flowed about70 metres higher than today and the confluence came through a series of rapids and little stairs more or less marked.
With the passing of the years, while the Nera river deepen its course, the Velino, above all in the confluence area, accumulated great quantities of travertine, seeing that the waters are enriched by calcium carbonate from the springs located at the bottom. Here, the morphological conditions, together with the great quantity of vaporized water from the falls and from the rapids, created an enormous travertine dam. The consequence was to stop completely the only opening which allowed to evacuate all the canalized waters which collected in the Rieti basins.
Therefore the block at Marmore caused an accumulation of water at the bottom, swamping the Reatina Plain. We are almost in an important period in which in a short time, we see development of a great hydraulic engineering scheme work: the Romans, foresaw the enormous power of the soils fertility that form the swamp beds, engraved with a channel the surface area of a travertine plastron and in this way the waters of the Velino recommended to fall internally in the bed of the Nera River recreating ,also, a waterfall at Marmore.
In the naturalistic area of the Marmore Falls exists more than 300 natural caves, all these are explored by the Bat Speleological group of CAI (Italian alpine club) of Terni.