VOLCANOES. 



841 



eastern limit, since the country beyond the Caspian 

 and sea of Aral is scarcely known. The southern 

 boundaries of the region include the most northern 

 parts of Africa, and part of the desert of Arabia. 

 We may trace, through the whole of the area com- 

 prehended within these extensive limits, numerous 

 points of volcanic eruptions, hot springs, gaseous 

 emanations, and other signs of igneous agency ; 

 while few tracts of any extent have been entirely 

 exempt from earthquakes throughout the last 3000 

 years. Besides the continuous spaces of subterran- 

 ean disturbance, of which the outline has been 

 given above, there are other disconnected volcanic 

 groups, of which the geographical extent is, as yet, 

 imperfectly known. Among these may be men- 

 tioned Iceland, which belongs, perhaps, to the same 

 region as the volcano in Jan Mayen's island. With 

 these, also, part of the nearest coast of Greenland, 

 which is sometimes shaken by earthquakes, may be 

 connected. The island of Bourbon belongs to 

 another theatre of volcanic action, of which Mada- 

 gascar probably forms a part, if the alleged existence 

 of burning volcanoes in that island shall be sub- 

 stantiated. Respecting the volcanic system of 

 Southern Europe, it may be observed, that there 

 is a central tract, where the greatest earthquakes 

 prevail, in which rocks are shattered and cities laid 

 in ruins. On each side of this line of greatest com- 

 motion, there are parallel bands of country where 

 the shocks are less violent. At a still greater dis- 

 tance, as in Northern Italy, there are spaces where 

 the shocks are much rarer and more feeble. Beyond 

 these limits, again, all countries are liable to slight 

 tremors at distant intervals of time, when some 

 great crisis of subterranean movement agitates an 

 adjoining volcanic region ; but these may be con- 

 sidered as mere vibrations, propagated mechanically 

 through the external crust of the globe, as sounds 

 travel almost to indefinite distances through the 

 air. Shocks of this kind have been felt in England, 

 Scotland, Northern France and Germany, particu- 

 larly during the Lisbon earthquake. 



We shall now give some account of a few of the 

 principal volcanic vents, dispersed through the great 

 regions before described, and consider the composi- 

 tion and arrangement of their lavas and ejected 

 matter. From the first colonization of Southern 

 Italy by the Greeks, Vesuvius afforded no other 

 indication of its vol- 

 canic character than 

 such as the naturalist 

 might infer from the 

 analogy of its structure 

 to other volcanoes. 

 These were recognised 

 by Strabo. The an- 

 cient cone was of a very 

 regular form, terminat- 

 ing, not, as at present, in two peaks, but with a 

 flattish summit, where the remains of an ancient 

 crater, nearly filled up, had left a slight depression, 

 covered in its interior by wild vines, and with a 

 sterile plain at the bottom. On the exterior, the 

 sides of the mountains were covered with fertile 

 fields, richly cultivated, and at its base were the 

 populous cities of Herculaneum and Pompeii. But 

 the scene of repose was at length doomed to cease, 

 and the volcanic fire was recalled to the main chan- 

 nel, which, at some former, unknown period, had 

 given passage to repeated streams of melted lava, 

 sand and scoriae. The first symptom of the revival 

 of the energies of this volcano was the occurrence 



of an earthquake. A. D. 63, which did considerable 

 injury to the cities in its vicinity. From that time 

 to the year 79, slight shocks were frequent ; and in 

 the month of August of that year, they became 

 more numerous and violent, till they ended at 

 length in an eruption. The elder Pliny, who com- 

 manded the Roman fleet, was then stationed at 

 Misenum ; and, in his anxiety to obtain a near view 

 of the phenomena, he lost his life, being suffocated 

 with sulphureous vapours. His nephew, the younger 

 Pliny, remained at Misenum, and has given us, in 

 his Letters, a lively description of the awful scene. 

 A dense column of vapour was first seen rising ver- 

 tically from Vesuvius, and then spreading itself out 

 laterally, so that its upper portion resembled the 

 head, and its lower, the trunk or the pine, which 

 characterizes the Italian landscape. This black 

 cloud was pierced, occasionally, by flashes of fire as 

 vivid as lightning, succeeded by darkness more pro- 

 found than night. Ashes fell even upon the ships 

 at Misenum, and caused a shoal in one part of the 

 sea. The ground rocked, and the sea receded from 

 the shores, so that many marine animals were seen 

 on the dry sand. The appearances above described 

 agree perfectly with those witnessed in more recent- 

 eruptions, especially those of Monte Nuovo, in 

 1538, and of Vesuvius, in 1822. In all times and 

 countries, indeed, there is a striking uniformity in 

 the volcanic phenomena; but it is most singular 

 that Pliny, although giving a circumstantial detail 

 of so many physical facts, and enlarging upon the 

 manner of his uncle's death, and the ashes which 

 fell when he was at Stabiae, makes no allusion 

 whatever to the sudden overwhelming of two large 

 and populous cities, Herculaneum and Pompeii. 

 Tacitus, the friend and contemporary of Pliny, 

 when adverting, in general terms, to the convulsion, 

 says merely, that " cities were swallowed up or 

 buried" (haustce aut obrutK urbes. Hist. lib. i.). It 

 does not appear that, in the year 79, any lava flowed 

 from Vesuvius: the ejected substances appear to 

 have consisted entirely of sand and fragments of 

 older lava. In 1036, the first eruption of flowing 

 lava occurred. A second happened in 1049, and a 

 third in 1 138 ; after which a great pause ensued of 

 168 years. During part of 1301, earthquakes had 

 succeeded one another with fearful rapidity ; and 

 they terminated at last with the discharge of a lava 

 stream from a point named the Campo del Arso, 

 not far from the town of Ischia. This lava ran 

 quite down to the sea a distance of about two 

 miles. Its surface is of a reddish-black colour ; 

 and it is almost as sterile, after a period of five 

 centuries, as if it had cooled down yesterday. The 

 next eruption occurred in 1306 ; between which 

 era and 1631, there was only one other (in 1500), 

 and that a slight one. During this interval, a me- 

 morable event occurred in the Phlegraean fields 

 the sudden formation of a new mountain in 1538. 

 Frequent earthquakes for two years preceding dis- 

 turbed the neighbourhood of Pozzuoli ; but it was 

 not until the twenty-seventh and twenty-eighth of 

 September, 1538, that they became alarming, when 

 not less than twenty shocks were experienced in 

 twenty-four hours. At length, on the night of the 

 twenty-ninth, two hours after sunset, a gulf opened 

 between the little town of Tripergola, which once 

 existed on the site of the Monte Nuovo, and the 

 baths in its suburbs, which were much frequented. 

 A large fissure approached the town with a tremen- 

 dous noise, and began to discharge pumice-stones, 

 blocks of unmelted lava, and ashes mixed with 



