228 FIRST YEAR COURSE IN GENERAL SCIENCE 



most severe ones of modern times were undoubtedly due 

 to faulting, as no marked volcanic disturbance occurred at 

 the same time. 



In 1908 two large cities on opposite sides of the Strait of 

 Messina were almost totally destroyed by violent earth- 

 quake shocks. Seventy-five thousand people were killed 

 and as many more were injured or rendered homeless. 

 Practically every building of any considerable height was 

 wrecked. The center of the disturbance was under the sea 

 in the Strait of Messina. An earthquake second only to 

 that of Messina occurred early in 1915 in the Italian prov- 

 ince of Abruzzi in the Apennine Mountains. There are no 

 large cities in this region, but many towns and villages 

 were completely destroyed, and all communication by wire 

 and rail was cut off. The loss of life was between twenty 

 and thirty thousand. The tremors were felt to a distance 

 of three hundred miles and some of the monuments and 

 ancient buildings in Rome were damaged. 



248. Volcanoes. Scattered over the earth, sometimes 

 in groups but often singly, there are cone-shaped elevations 

 called volcanoes, or volcanic mountains. If a volcano is 

 active, steam is seen rising above its summit; fine rock dust, 

 called ash, is blown in clouds from the opening at the top; 

 and melted rock, or lava, pours down the slope'. At the 

 summit of many volcanoes there is a bowl-shaped depression 

 called the crater, which is sometimes partly filled with lava 

 even when none flows over the edges. 



A volcano is said to be dormant when for a long time 

 there has been no sign of activity. If sufficient time has 

 elapsed for the crater to become filled with rock waste or 

 water, and the sides to be covered with soil and forested or 

 cultivated, the volcano is considered extinct. Mount Shasta, 

 an extinct or dormant volcano of California, has been quiet 

 so long that glaciers have formed upon its sides. Mount 

 Lassen, another California volcano, began to send out 



