162 PHYSIOGRAPHY 



the glowing lava in the cracks of the crater's floor lights up the clouds 

 of steam which hover over the mountain. It is for this reason that 

 Stromboli is known as "the lighthouse of the Mediterranean." 

 The eruptions of Stromboli are occasionally so violent that the roar 

 of the escaping steam may be heard for miles, while the lava is 

 hurled so high and so far that it is scattered not only over the entire 

 mountain, but into the surrounding sea. 



Vesuvius. Vesuvius, near Naples, Italy, is probably the best 

 known \*olcano. Its cone is a mountain about 4,000 feet high. 

 Its present cone (Fig. 163) rises within the half-destroyed rim of 

 an older and much larger crater. 



Previous to 79 A. D., Vesuvius was, so far as then known, only 

 a conical mountain in whose summit was a deep crater three miles 

 in diameter. The slopes and even the bottom of the crater were 

 covered with vegetation. In that year a terrible explosion occurred, 

 which blew away half the rim of the crater. Much of the rock 

 blown out was broken into such small pieces as to constitute dust 

 (often called volcanic ash) , and as it fell on the surrounding country, 

 it buried and destroyed not only plants, but even cities. Pompeii, 

 a city of some 20,000 inhabitants, was thus buried, and about 2,000 

 of its people were killed. Heavy rains accompanied or followed 

 the eruption. Falling on the volcanic dust, the water gave rise 

 to streams of hot mud. Herculaneum was overwhelmed by such 

 a stream. The present cone of Vesuvius was built up inside the 

 remnant of the rim of the older cone after this eruption. 



Since the outburst of 79, Vesuvius has had other violent erup- 

 tions, separated by periods of quiet. The eruption of 1631 was 

 especially violent, destroying some 18,000 lives. Another eruption 

 of great violence occurred in 1872. For several months before there 

 had been slight eruptions, during which steam and small fragments 

 of rock issued from the crater, and lava flowed from the cracks on 

 the mountain-side. The activity gradually increased in violence 

 until April, when two huge fissures and several smaller ones opened 

 on the flanks of the cone, and from them streams of lava flowed 

 into the neighboring valleys, overwhelming two villages. At the 

 same time, two large openings were made at the summit, from which 

 enormous quantities of steam, dust, and masses of molten rock 



