According to M. Elie de Beaumont, Etna is an irregular crater of elevation. The original deposits were nearly horizontal, and lavas were poured through fissures in these, and accumulated at first in layers; afterwards the whole mass was upheaved and a crater formed.[20] The upheaving force does not appear to have acted at one point, but along a line traversing the Val del Bove. The latter he refers to a subsidence of a portion of the mountain. He divides the rocks of Etna into six orders: 1. The lowest basis of the mountain would appear to consist of granite, because masses of that rock have from time to time been ejected. 2. Calcareous and arenaceous rocks, of which the mountains surrounding Etna are composed, and which appear capped with lava near Bronte and elsewhere. 3. Basaltic rocks, which are met with near Motta S. Anastasia, Paterno, Licodia, and Aderno, and in the Isole de'Ciclopi. 4. Rolled pebbles, which form a range of slightly rising ground between the first slopes of Etna on the southern side and the plain of Catania. (Lyell speaks of this rising ground as consisting of "argillaceous and sandy beds with marine shells, nearly all of living Mediterranean species, and with associated and contemporaneous volcanic rocks.") 5. Ancient lavas forming the escarpments around the Val del Bove; and 6th, Modern lavas. He considers that the fissures which abound on Etna are shifts or faults produced by dislocation, and that the minor cones are points along such fissures from which ashes and lava have been ejected. He admits the existence of two cones. The geological map of Etna prepared by M. Elie de Beaumont to accompany his memoir can scarcely be regarded as a great addition to our knowledge of the mountain. For although in the main points it is correct, so many details have been omitted that the map must be considered to have now been quite superseded by those of Von Waltershausen and Friedrich Hoffmann. [20] "Récherches sur la structure et sur l'origine du Mont Etna." 1836.