168 DYNAMICAL GEOLOGY. 



level. All this was done so quietly that it was unre- 

 marked by contemporaneous writers. 



There is good reason to think that the whole took 

 place between A. D. 1200 and 1600. Writers of the six- 

 teenth century say that in 1530 one might stand on the 

 cliff, b, and fish in the sea ; this, therefore, was during 

 the period of subsidence. Now, in 1198 a great earth- 

 quake destroyed Pozzuoli, and in 1535 Monte Nuovo was 

 formed by eruption. It is probable, therefore, that the 

 history of events was briefly this : After the earthquake 

 of 1198, the sinking commenced, and continued until it 

 reached twenty-one feet ; it remained in this condition 

 until the eruption of 1535, when it began to rise again. 

 During the interval of subsidence, sediments, volcanic 

 ashes, etc., filled up the bottom twelve feet deep, and 

 protected the lower part of the columns, and only the 

 part representing clear water was bored. 



Other evidences of movements up or down are found 

 all along the coasts of the Mediterranean. The ruins of 

 the Temple of the Nymphs are now in water. The bridge 

 of Caligula is bored several feet above the sea-level, etc. 



3. Sweden and Norway. The examples thus far given 

 are in volcanic countries, and possibly caused by volcanic 

 forces ; but such movements are by no means always asso- 

 ciated with volcanism ; for example, Scandinavia is re- 

 markably free from volcanism, and yet the whole coast, 

 both on the Atlantic and the Baltic side, has been for a 

 long time, and is still, rising out of the sea. The rate is 

 less in the southern part and increases northward, the 

 average being about two to three feet per century. That 

 this has been going on for a long time is shown by old 

 beach-marks at various levels up to six hundred feet above 

 sea-level, showing an elevation to that extent, and that 

 during the present geological epoch. At the rate of two 

 and a half feet per century, this would require two hun- 

 dred and forty centuries, or twenty-four thousand years. 



