Etna : a history of the mountain and of its eruptions . monts classification of rocks of Etna.—Hoffmansgeological map.—Lyells researches.—The period of earliesteruption.—The Val del Bove.—Two craters of eruption.—An-tiquity of Etna.—The lavas of Etna.—Labradorite.—Augite.—Olivine.—Analcime.—Titaniferous iron.—Mr. Rutleys examina-tion of Etna lavas under the microscope. The opinion of geologists is divided as to the mannerin which a volcano is first formed. Some hold that thevolcanic forces have upraised the rocks from beneath, andat last finding vent have scattered the lighter portionsof such
Etna : a history of the mountain and of its eruptions . monts classification of rocks of Etna.—Hoffmansgeological map.—Lyells researches.—The period of earliesteruption.—The Val del Bove.—Two craters of eruption.—An-tiquity of Etna.—The lavas of Etna.—Labradorite.—Augite.—Olivine.—Analcime.—Titaniferous iron.—Mr. Rutleys examina-tion of Etna lavas under the microscope. The opinion of geologists is divided as to the mannerin which a volcano is first formed. Some hold that thevolcanic forces have upraised the rocks from beneath, andat last finding vent have scattered the lighter portionsof such rocks into the air, and have poured out lavathrough the rent masses, thus forming a crater ofelevation. Others maintain that the volcanic productsare ejected from an aperture or fissure already existingin rocks previously formed, and that the accumulation ofthese products around the vent forms the mass of thevolcano and the crater of eruption. Lyell favours thelatter view; Yon Buch, Dufrenoy, and Elie de Beau-mont the
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Keywords: ., bookauthor, bookcentury1800, bookdecade1870, booksubjectvolcanoes
