No. III. — Pausilipo and the Lago cVAgnano. ^53 



sought for only in aboriginal craters, since they were not 

 readily accounted for by the abrading influence of the water. 

 Craters no doubt may be found prior to the retirement of the 

 waters, according to this theory ; but they are extremely bro- 

 ken down, and low, and imperfect in their outline. Such we 

 may conceive to have been the case with the basin in which 

 the Lake of Agnano lies, and perhaps that of Avernus ; but as 

 to the scarped craters of Astroni, Solfatara, &c. I believe I 

 am not singular in thinking that they owe their present fea- 

 tures to eruptions subsequent to the elevation of this district, 

 or the lowering of the level of the water ; which action is most 

 probable I shall not here consider. It is at least certain that 

 Solfatara was in eruption in the 12th century, which proves it 

 in that particular. 



Respecting the hill of Pausilipo, of the features of which I 

 have given some account, it seems especially to answer to the 

 supposed course of nature above proposed. Its interior solidity 

 answers well to the supposition that it was the substratum of 

 a great elevated fluid mass, while the more refined and pumi- 

 ceous substances are disposed in strata on the top. In as far 

 as these strata follow the shape of the hill, we may be disposed 

 to admit that they were first deposited, and the elevation of 

 the subjacent mass then took place ; and we may observe, that 

 the features of the hill quite unfit it for a portion of the wall 

 of a great crater extending to Agnano, as Breislak supposes. 

 He has completely perverted the form of the promontory, by 

 giving it a turn to the westward ; instead of which, in reality, 

 its line of direction makes it tend to the island of Nisida ; and 

 the small hill of Sta. Teresa, which he enlists as a fragment of 

 this degraded crater, is far liker a small regular crater of itself. 

 Besides all this, the hill of Pausilipo will not bear the test of 

 the most established rules, as to the true designation of a volca- 

 nic crater. Daubeny judiciously remarks, I think from Von 

 Buch, that a true crater has all the lines of its stratification 

 directed to the apex of the cone which would be formed, were 

 the hill complete ; but we have seen how totally inconsistent 

 the spot before us is with such a supposition, being both inter- 

 nally and externally of a flattish saddle-shaped stratification. 

 With these few remarks, which will convey my general ideas 



