Stones that rise up

Normally the concept of “stone” is associated with its weight, …“heavy as a rock”, “drop like a stone”, “stones in water go straight to the bottom”…. And in fact it almost never happens in nature that stones can rise up, especially over long tracts with big differences in height.

And yet in the Grotta del Vento it has happened, the proof is undeniable and documented with photographs.

Right from the start of the work to open the cave to the public there was the hypothesis of a water connection between the initial siphon, which tourists pass by means of a short man-made tunnel, and the area of the Acheronte River, situated in the deepest part of the “second itinerary”, where there are many smooth round pebbles and light sand. But this connection was not visible and, thinking that it was buried by detritus, around the end of the 80’s an excavation was made on the bottom of the initial siphon, but no passage was found. However it was noticed that on one wall there was a hole of about 60 centimetres in diametre, which was immediately explored for a length of about fifteen metres, until a point where the extremely narrow tunnel disappeared into the water and mud.

The search was therefore abandoned, but on the 20^th October 2013 something unexpected happened which confirmed the hypothesis of a connection. During the night a violent storm caused the Acheronte river to rise up 60 metres in level, making it overflow into the 1^st itinerary, causing water to flow out of the entrance with a capacity of 6 cubic metres per second.

A few weeks later, at the bottom of the initial siphon, by that time dried up, it was noticed under the hole in the wall which had previously been explored a very diverse pile of rounded stones, mixed with light sand. Both the stones, some of which weighed more than half a kilo, and the sand, were identical to those which make up the river bed of the Acheronte. Stones and sand of that type had never been seen in any other part of the Cave.

To have raised those stones up 30 metres (that is the difference in level which separates the  Acheronte from the initial siphon) the water current must have been extremely violent. To have that speed it has been hypothesized that the conduit must be particularly narrow and smooth, maybe impracticable for man, and above all without any expansion which, slowing down the current, would have provoked the decantation of solid matter.