five distinct craters — the Northeast Crater, the Voragine, the Bocca Nuova, and the Southeast Crater Complex (2).

archeomagnetic dating-75

The steep walls of the valley have suffered subsequent collapses on numerous occasions.

The strata exposed in the valley walls provide an important and easily accessible record of Etna's eruptive history.

In Greek Mythology, the deadly monster Typhon was trapped under this mountain by Zeus, the god of the sky and thunder and king of gods, and the forges of Hephaestus were said to also be located underneath it.

Mount Etna is one of the most active volcanoes in the world and is in an almost constant state of activity.

The most recent collapse event at the summit of Etna is thought to have occurred about 2,000 years ago, forming what is known as the Piano Caldera.

This caldera has been almost entirely filled by subsequent lava eruptions, but is still visible as a distinct break in the slope of the mountain near the base of the present-day summit cone.

Mediaevalist Roger Sherman Loomis quotes passages from the works of Gervase of Tilbury and Caesarius of Heisterbach ( dating from the late twelfth century ) featuring accounts of Arthur's returning of a lost horse which had strayed into his subterranean kingdom beneath Etna.

Caesarius quotes as his authority for the story a certain canon Godescalcus of Bonn, who considered it a matter of historic fact of the time of Emperor Henry's conquest of Sicily circa 1194.

The name Mongibel is found in Arthurian Romance, as the name of the otherworld castle ( or realm ) of Morgan le Fay and her half-brother, King Arthur, localised at Etna, according to traditions concerning them derived from the stories told by the Breton conteurs who accompanied the Norman occupiers of Sicily.