Notice of Active and Extinct Volcanos. 273 



The central portion of Italy is occupied by a vast deposit 

 of blue clay or marl containing numerous and thick beds of 

 gypsum, with sulphur and the sulphurets of iron and copper. 



" The crystals of sulphat of strontian, found in the sulphur 

 mines are unrivalled for their beauty; and are mixed with 

 those of sulphur, lining the fissures, often in large and regu- 

 lar octahedral 1 



The celebrated mud eruptions especially at Macaluba, 

 which sometimes throw mud, bitumen and gases, mixed, to 

 the height of two hundred feet are attributed by Professor 

 Daubeny to the slow combustion of beds of sulphur. But we 

 dismiss subordinate considerations that we may bestow the 

 greater attention on iEtna. 



Mtna. 



" This mighty and imposing mountain, which rises in solitary 

 grandeur to the height of above ten thousand feet, and embraces. 

 a circumference of one hundred and eighty miles, is entirely 

 composed of lavas, which, whatever subordinate differences may 

 exist between them, all possess the appearance of having been 

 ejected above the surface of water, and not under pressure. 



" In the structure of this mountain, every thing wears alike 

 the character of vastness. The products of the eruptions of Ve- 

 suvius may be said almost to sink into insignificance, when com- 

 pared with these coulees, some of which are four or five miles in 

 breadth, fifteen in length, and from fifty to one hundred feet in 

 thickness, and the changes made on the coast by them are so con- 

 siderable, that the natural boundaries between the sea and land 

 seem almost to depend upon the movements of the volcano. 



" The height too of Etna is so great, that the lava frequently 

 finds less resistance in piercing the flanks of the mountain, than 

 in rising to its summit, and has in this manner formed a number 

 of minor cones, many of which possess their respective craters, 

 and have given rise to considerable streams of lava. 



" Hence an antient poet has very happily termed this volcano 

 the parent of Sicilian mountains, an expression strictly applica- 

 ble to the relation which it bears to the hills in its immediate 

 neighborhood, all of which have been formed by successive ejec- 

 tions of matter from its interior. 



" The grandest and most original feature indeed in the physi- 

 ognomy of Etna, is the zone of subordinate volcanic hills with 

 which it is encompassed, and which look like a court of subaltern 

 princes waiting upon their sovereign. 



" Of these, some are covered with vegetation, others are bare 

 and arid, their relative antiquity being probably denoted by the 



Vol. XIII.— No. 2. 10 



