A number of caverns are met with in various parts of Etna; Boccacio speaks of the Cavern of Thalia, and several early writers allude to the Grotto delle Palombe near Nicolosi. The latter is situated in front of Monte Fusara, and the entrance to it is evidently the crater of an extinct monticule. It descends for 78 feet, and at the bottom a cavern is entered by a long shaft; this leads to a second cavern, which abruptly descends, and appears to be continued into the heart of the neighbouring Monti Rossi. Brydone says that people have lost their senses in these caverns, "imagining that they saw devils, and the spirits of the damned; for it is still very generally believed that Etna is the mouth of Hell." Many of the caverns near the upper part of the mountain are used for storing snow, and sometimes as places of shelter for shepherds. We have already seen to what extent Lucretius attributed the eruptions to air pent up within the interior caverns of the mountains. The surface of the mountain has been divided into three zones or regions--the _Piedimontana_ or _Coltivata_; the _Selvosa_ or _Nemorosa_; and the _Deserta_ or _Discoperta_. Sometimes the name of _Regione del Fuoco_ is given to the central cone and crater. As regards temperature, the zones correspond more or less to the Torrid, Temperate, and Frigid. The lowest of these, the _Cultivated Region_, yields in abundance all the ordinary Sicilian products. The soil, which consists of decomposed lava, is extremely fertile, although of course large tracts of land are covered by recent lavas, or by those which decompose slowly. In this region the vine flourishes, and abundance of corn, olives, pistachio nuts, oranges, lemons, figs, and other fruit trees. The breadth of this region varies; it terminates at an approximate height of 2000 feet. A circle drawn with a radius of 10 miles from the crater, roughly defines the limit. The elevation of this on the north is 2,310 feet near Randazzo; on the south, 2,145 feet near Nicolosi; on the east, 600 feet near Mascali; and on the west, 1,145 feet near Bronte. The breadth of this cultivated zone is about 2 miles on the north, east, and west, and 9 or 10 on the south, if we take for the base of the mountain the limits proposed above. The _Woody Region_ commences where the cultivated region ends, and extends as a belt of varying width to an approximate height of 6,300 feet. It is terminated above by a circle having a radius of nearly 1-1/2 miles from the crater. There are fourteen separate forests in this region: some abounding with the oak, beech, pine, and poplar, others with the chestnut, ilex, and cork tree.