EARTH Q UAKE-PHENOMENA. 5 1 5 



or night. On the night of the 29th, flames issued from the ground 

 near the baths of Nero, the earth rose and burst at the top with tre- 

 mendous roar, and discharged steam, gas, pumice, mud, and ashes. A 

 mountain 1,000 feet high was formed, known as Monte Nuovo, which, 

 at the present time, is 8,000 feet in circumference, and 440 feet above 



Fio. 1. 



Monte Nuovo. 



the bay. The present aspect of Monte Nuovo is represented in Fig. 

 1, and the region around is shown in the frontispiece, from the last 

 edition of Lyell's " Principles of Geology." 



The Phlegrsean Fields, of which Monte Nuovo now forms a part, 

 have, in the opinion of Sir Charles Lyell, a " mutual relation with Ve- 

 suvius a violent disturbance in one district serving as a safety-valve 

 to the other both never being in full activity at once." 



In the Sandwich Islands, in 1868, Mauna Loa and the craters of 

 Kilhauea on its flank were in active eruption. The valleys of the 

 mountains were filled with rivers of fire, and a cloud of smoke and 

 vapor arose, it is said, over the mountain, to a height of eight 

 miles. During these fearful phenomena, which continued more than 

 a month, 1,500 earthquake-shocks occurred, 300 of which were counted 

 in five days. But whether shocks occur in the immediate vicinity of 

 volcanoes during eruptions, or whether activity of the one diminishes 

 the violence of the other, it is certain that they have a mutual relation, 

 and probably a common origin. 



The opening and closing of fissures and chasms in the ground dur- 

 ing earthquakes is a common phenomenon. Men, animals, and dwell- 

 ings, are sometimes swallowed in them, and forever disappear. In 

 1848 an earthquake shook a large portion of New Zealand, and a 

 fissure of great depth opened along a chain of mountains from 1,000 



