106 PHENOMENA OF SUBMARINE ERUPTIONS. 



without any apparent ejection ; and, in 1806, it formed a cone which might 

 be seen from Unalaska, and upon it were four other smaller ones, on the 

 north-west side. 



Santorin. The Mediterranean also furnishes a fine example of submarine 

 eruptions, in the midst of the space comprised between the islands of San- 

 torin, Teresia and Aspronisi (Jig. 193), which, according to the ancients, 

 appeared above the water several centuries before the Christian era, in con- 

 sequence of violent earthquakes. In this circuit, Hiera arose first, 186 years 

 before our era, which subsequently grew by little islets rising on its borders 

 in the years 19, 726, 1427 ; then, in the same way, Micra-Kameni, in 1573, 

 and Nea-Kameni, in 1707, were formed ; and successively growing in 1709, 

 1711, 1712, &,c. No crater was formed in either of these islands, and we 

 only hiive there the appearance of volcanic matter in form of a do?ne, which 

 seems to have covered the orifice through which it escaped. There was no 

 volcan there, according to the terms of our definition, but a tendency to form 

 one at some future time. The islands of Milo, Argentiera, Polino, Policau- 

 dro, Poios, &c., are formed of the same materials, and probably had the same 

 origin. 



13. Wliat passes in these phenomena. These submarine phe- 

 nomena are announced by incandescent matters ejected above 

 water ; by scoriss and pumice, which float on the surface ; by burn- 

 ing rocks, which appear in the midst of waves of vapour, and by 

 the boiling of the sea, the temperature of which becomes very 

 much increased. All these things occurred in our own times, at 

 Julia, at Sabrina, &c., and are such as authors mention in detail, in 

 all their accounts. Father Goree has given us a history of the 

 upheaval of Nea-Kameni, of Santorin, in 1707; and all the cir- 

 cumstances he relates agree with what Strabo, Pliny, Plutarch and 

 Justin tell us of the appearance of Hiera, in the midst of flames, 

 and a violent ebullition of the sea. 



But the circumstances we have just spoken of are not always all present 

 at the same time. Sometimes no solid rock appears above water ; this 

 was the case at Kamtschatka, in 1737, where jets of vapour, great ebul- 

 lition of the sea, and pumice-stones floating on the surface, were all that 

 was perceived ; but when the spot could be approached, there was found a 

 chaia of submarine mountains, where there had been previously a depth of 

 more than a hundred fathoms. In certain cases there is not even a jet of 

 vapour, and the phenomenon is manifested by the heat of the water only ; 

 this happened in 1820, at the island of Banda, among the Moluccas, where 

 the bay, which was upwards of fifty fathoms deep, was filled by the tranquil 

 elevation of compact basa'ltic matter, probably pre-existing, which formed 

 an elevated .promontory composed of large blocks piled one on the other; 

 and its appiarance was manifested by the heat of the water only. It also 

 beems, that after eruptions, there is often a peaceful and slow upheaval, as 

 in the island formed before Unalaska, and at Santorin, according to the 

 observations of M. Virlet. Indeed, between Micra-Kameni and the port of 

 Phira, where there is an abrupt submarine mountain, there was, at the be- 

 /inning of the present century, fifteen fathoms of water above the highest 

 part , but there were only four fathoms in 1830, and little more than two in 

 1834. It is presumed a new island, that is, the summit of a new cone, 

 will appear in the gulf, and the appearance will, probably, be accompanied 

 by sur.h phenomena as we mention. 



13 What pnenomena occur in submarine eruptions ? 



