INTERIOR LAND CHANGES. 



433 



,' I 



Circular Hollows at Polistena. 



the bottom upwards. Valleys underwent extensive and striking alterations through the 

 precipitation into them of masses from the neighbouring hills. Fissures, radiating from 

 a central point, or single horizontal openings of the ground, appeared in various places, 



as at Polistena, where the ground was rent asunder to 

 a great length and depth. A permanent chasm in the 

 district of Rosiano was a mile long, upwards of a hundred 

 feet broad, and thirty deep. Some of these fissures, after 

 swallowing up houses and men, closed and opened again, 

 so that property was recovered, and the victims of the 

 catastrophe were restored to the rites of burial. The most 

 singular landslip occurred near Seminaria, where a large 



olive-ground descended 

 from the heights into 

 the valley, retaining its 

 compactness, a house 

 upon it standing firm, 

 and the olives continued 

 to grow in their new 

 situation, bearing an 

 abundant crop the same 

 year. In the plains, a 

 considerable number of 

 circular funnel-shaped 

 hollows were formed, 



filled with water or sand, a consequence of the vorticose or whirling motion of the earth. 

 These are a sample of the effects in one region, of a cause, to the influence of which a 

 vast area of the globe is exposed. We are presented with a continued series of such 

 operations from the earliest times of which we have any knowledge, and hence the fact 

 is sufficiently obvious, that the aggregate has largely altered the physical condition of the 

 globe, though we cannot estimate the amount of the change. The ancients were not 

 much addicted to physical inquiry ; they contented themselves with general tillusions in 

 their writings to natural phenomena ; yet we learn enough from these slight notices 

 to know that, in their day, " Vulcan's habitation " was rife with " terrific flashes," with 

 " noise and terror ; " 



Vulcani domus 



Fulgores terrificos, sonitumque metumque: 



and, brief as is the reference of Thucydides to the earthquake at Euboea, writing four 

 centuries before Christ, the leading features of the account will apply to that at Lisbon, 

 or Messina, twenty-one centuries afterwards. 



We are left entirely to hypothesis as to the cause of earthquakes and volcanic eruptions, 

 but of the oneness of that cause no doubt remains. The theory first started by Sir 

 Humphrey Davy, suggested by his discovery of the metallic bases of the earths and 

 alkalis, and since elaborated by Dr. Daubeny, has found very general acceptance. 

 According to this hypothesis, which is that of Subterranean Oxidation, the earth is 

 supposed to contain in its interior, at a great depth and in sufficient quantity, the earthy 

 and alkaline metalloids, iron, sulphur, and sulphuretted salts. These are substances 

 which combine with oxygen with avidity, a high temperature and strong inflammation 

 being the result of the combination. A supply of water reaching the interior of the earth, 

 becomes decomposed by contact with the metalloids, and yields its oxygen to them, 

 occasioning the phenomena of combustion and explosion, which may be imitated upon a 



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