IGNEOUS AGENCIES. 161 



beneath the sea-bed, perhaps one hundred miles off shore. 

 The arrival of the earth-wave shook down the houses. 

 Then, after a half-hour, when all was quiet, there came 

 great sea waves sixty feet high and completed the destruc- 

 tion of the city. These waves were sixty feet high at 

 Lisbon, thirty feet at Cadiz, eighteen feet at Madeira, and 

 five feet on the coast of Ireland. They were also felt on 

 the coast of Norway and on the West India Islands, after 

 having traversed the breadth of the Atlantic. 



2. In 1854 an earthquake shook the coast ,of Japan. 

 A half -hour afterward a great wave, thirty feet high, came 

 in and swept the town of Simoda clean away. The epi- 

 centrum was probably a hundred miles off shore. The 

 wave, spreading in all directions, was highest on the coast 

 of Japan, because this was near the epicentrum. But in 

 the other direction it was observed at the Bonin Islands 

 fifteen feet high, and after traversing the Pacific and 

 being nearly exhausted on the California coast, only 

 eight inches high at San Francisco and six inches at San 

 Diego. 



3. In August, 1868, a very destructive earthquake 

 shook the coast of Peru, severest about Arica. The epi- 

 centrum was not far off shore, for in five minutes after- 

 ward there came in great sea waves sixty feet high and 

 desolated the whole coast, carrying ships far inland and 

 stranding them high up on the mountain slopes. These 

 great waves were traced southward to Coquimbo and be- 

 yond, northward to San Francisco, Astoria, and Sitka, 

 southwestward to Australia and New Zealand, and west- 

 ward to Hawaii and Japan, thus having traversed the 

 whole breadth of the Pacific. Were it not for the obstruct- 

 ing continents, there is no doubt that they would have 

 encompassed the earth in their widening circles. 



In regard to these waves, there are several points worthy 

 of notice : 



a. Their velocity, though less than that of earth-waves, 



LE CONTE, GEOL. 11 



