G46 



OBJECTS DISCOVERED IN 



[Ch. XXV. 



Pomp 



Herculaneum 



the case is different. Although the substance 

 which fills the interior of the houses and the vaults in that 

 buried city must have been introduced in a state of mud, like 

 that found in similar situations in Pompeii ; yet the super- 

 incumbent mass differs wholly in composition and thickness. 

 Herculaneum was situated several miles nearer to the vol- 

 cano, and has, therefore, been always more exposed to be 

 covered, not only by showers of ashes, but by alluviums and 

 streams of lava. Accordingly, masses of both have accu- 

 mulated on each other above the city, to a depth of nowhere 

 less than 70, and in many places of 112 feet.* 



The tuff which envelopes the buildings consists of com- 

 minuted volcanic ashes, mixed with pumice. A mask em- 

 bedded in this matrix has left a cast, the sharpness of which 

 was compared by Hamilton to those in plaster of Paris ; nor 

 was the mask in the least degree scorched, as if it had been 

 imbedded in heated matter. This tuff is porous ; and, when 

 first excavated, is soft and easily worked, but acquires a con- 

 siderable degree of induration on exposure to the air. Above 

 this lowest stratum is placed, according to Hamilton, 'the 

 matter of six eruptions/ each separated from the other by 

 veins of good soil. In these soils Lippi states that he col- 

 lected a considerable number of land shells — an observation 

 which is no doubt correct ; for many snails burrow in soft 

 soils, and some Italian species descend, when they hybernate, 

 to the depth of five feet and more from the surface. Delia 

 Torre also informs us that there is in one part of this super- 

 imposed mass a bed of true siliceous lava (lava di jpietra dura) ; 

 and, as no such current is believed to have flowed till near 

 1,000 years after the destruction of Herculaneum, we must 

 conclude, that the origin of a large part of the covering of 

 Herculaneum was long subsequent to the first inhumation of 

 the place. That city, as well as Pompeii, was a seaport. 

 Herculaneum is still very near the shore, but a tract of land, 

 a mile in length, intervenes beneath the borders of the Bay 

 of Naples and Pompeii. In both cases the gain of land is 

 due to the filling up of the bed of the sea with volcanic 



* Hamilton, Observ. on Mount Vesuvius, p. 94. London, 1774. 







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