Mount Etna otherworldly associations of the great, volcanic mountain of their new home. 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. Caesarius employs in his account the Latin phrase "in monte Gyber" ("within Etna") to describe
Mount Etna accessible record of Etna's eruptive history. 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. Mount Etna is moving towards the Mediterranean Sea at an average rate of 14 mm per year, the massif sliding on an unconsolidated layer above the older sloping terrain. Eruptions of Etna follow a