MOUNTAIN FORMATION 



man. But earthquakes are doing constructive work as 

 well; or, at any rate, they are usually present when 

 constructive work is being done. Destructive forces, 

 such as erosion, are wearing down the structure of the 

 globe, while earthquakes are the only known forces that 

 are building it up. It is true that when an earthquake 

 occurs rocks often fall, loose sediment is shaken down, 

 and other settlements occur, but the real constructive 

 work consists in upheavals, little by little, as it may be, 

 of beaches, islands, coasts, plateaux, and perhaps larger 

 areas. These elevations are actually witnessed in certain 

 earthquakes. 



Many islands in the sea have been raised from time to 

 time within even living memory. 



The south-western part of the island of Crete has been 

 elevated within the historical period. 



The region about Pozzuoli and the Bay of Naples has 

 suffered both elevation and depression. There is the 

 famous instance cited by Sir Charles Lyell nearly eighty 

 years ago of the Temple of Jupiter Serapis. This 

 temple had many columns ; and they are now situated 

 on dry land. The pillars are forty-two feet in height, 

 and for twelve feet upwards they are of smooth undis- 

 figured marble. Then for another twelve feet they are 

 pitted with the holes made by a marine shell-fish called 

 LithodomuS) the stone-dweller. What are we to judge 

 from this? The temple was first built on dry land. 

 Then the land sank taking the temple with it, and the 

 columns were submerged in sea sediment to a depth of 

 some thirty feet above their pedestals. The lower por- 



181 



