On account of Mount Etna (Europe’s largest volcano), the island of Sicily is peppered with geological wonders. Starting with the summit craters of the volcano itself, right through to over 200 caves formed within lava tubes, the island is packed with volcanic sights.Chief among them is Gole dell ‘Alcantara, a system of gorges formed 8,000 years ago in the course of the river Alcantara in eastern Sicily.
The network of gorges have a maximum depth of 40 m and a width of up to 5 m. They are the result of intense, deep erosion, of 300,000 year old basaltic rocks, by flowing water. The lavas were once thought to originate from the nearby Monte Moio; an unusual crater not linked to the main Etna volcanic plumbing system. More recent research, including detailed petrographic studies, points towards the craters of Monte Dolce, in the medium-low side of Etna, as being the source of the lavas exposed in the Gole dell ‘Alcantara.
As today’s featured image shows, the lavas exposed throughout the gorge walls are remarkable. Erupting in river waters meant that the lavas cooled faster than they would have done otherwise, giving rise to fractures which formed prismatic structures. Some are chaotic, but others are arranged horizontally (locally known as the woodpile), slightly arching (the harp) and in a radial configuration known as the rosette. The most common configuration is the ‘organ pile’ where vertical fractures form, up to 30m high.
Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.