§H. 



MOUNT ETNA. 827 



A remarkable fact, arising from a similar cause, is men- 

 tioned by Count Strzelecki, as having come under his notice 

 in the valley of the Derwent in Van Diemen's Land. 

 Opalized coniferous wood is abundant, and in some parts 

 the truncated stumps are imbedded in porous and scoriaceous 

 basalt, and trachytic conglomerate, and in many instances 

 the basalt contains hollows, which are the moulds of trees that 

 have been consumed. It appears that the stems which had 

 been silicified withstood the intensity of the incandescent 

 lava ; while other trees, placed in circumstances unfavourable 

 to their previous petrifaction, were charred, but not de- 

 stroyed; and from their having been either green, or 

 saturated with water, they resisted the progress of com- 

 bustion, so as to leave cylindrical upright cavities in the 

 basaltic scoriae, with impressions similar to the rugged 

 bark of a carbonized tree. Into some of these hollows 

 a second eruption of lava has formed casts of the consumed 

 trunks in basalt.* 



14. Mount Etna. — This volcanic cone, which is situated 

 in the island of Sicily, and is entirely composed of erupted 

 mineral substances, rises majestically to the height of 

 upwards of two miles (or 10,872 feet), the circumference of 

 its base exceeding 180 miles ; on a clear day it may be dis- 

 tinctly seen from Malta, a distance of 150 miles. Compared 

 with this prodigious mass of igneous products, Vesuvius 

 sinks into insignificance ; for while the lava streams of the 

 latter do not exceed seven miles, those of Etna are often 

 from fifteen to thirty miles in length, and five miles in 

 breadth, and from fifty to one hundred feet in thickness, f 

 The surface of Etna presents three distinct regions: around 

 the base for an extent of twelve miles, the country is richly 

 cultivated, and abounds in vineyards and pastures, and is 

 the site of many towns, monasteries, and villages. The 



* Physical Description of New South Wales, 

 f Dr. Daubeny on Volcanoes. 



