The formation of the Alcantara riverbed dates back to about 300,000 years ago, however the current appearance of the river in the Gorges stretch dates back to the flows that occurred in the last 8,000 years. The presence of Monte Moio led initially to attribute the formation of the Gorges to this secondary cone.

Recent studies lead instead to distinguish three lava flows from open mouths in the Monte Dolce area, in the medium-low Etnean side, which overlapped and which are still visible along the wall on the left bank of the river; the oldest is the one that reached the Ionian Sea at Capo Schisò (Giardini Naxos), while the most recent is the one that formed the columnar basalt of the Gorges; the presence of the river water and the relative percolation inside the magma mass caused a faster cooling giving rise to deep irregular fractures (some even chaotic) which, intersecting, form prismatic structures of various configuration: wood-pile (Arranged horizontally),”harp” (slightly arched), “rosette” (radial pattern). The most regular formations are vertical, “organ-shaped”, and can even reach 30 meters.