166 DYNAMICAL GEOLOGY. 



accumulated, only gradual elevation would take place ; 

 but if the stiffness was very great, the yielding might 

 take place paroxysmally, by fracture, earthquake, and 

 sudden elevation. The normal process is, gradual eleva- 

 tion by gradual yielding. Earthquakes are but occasional 

 accidents in the slow march of these grand effects. 



But, besides these sudden elevations, there has been 

 during an immense time a gradual elevation of the whole 

 southern part of the South American Continent out of 

 the sea. The evidence of this is seen in the old beach- 

 marks one above another to the height of 1,300 feet 

 above the sea and extending along shore 2,000 miles on 

 the western and 1,100 miles along the eastern coast. 

 More recently, A. Agassiz has found on the same coast 

 dead corals of recent species sticking to the rocks 3,000 

 feet above sea. Here, then, we have continent-making 

 forces at work on a grand scale. It is not probable that 

 the whole of these effects was accomplished during the 

 present geological epoch, but they are the more interest- 

 ing on that very account, since we here trace geological 

 causes directly into causes now in operation. 



2. Italy. The most carefully observed example of 

 gradual elevation is that at the Bay of Baiae near Naples. 

 Fig. 86 is a map of the Bay of Baiae. From the present 

 shore-line there runs back a flat plain of stratified vol- 

 canic matter sloping gently to the sea, called the Starza; 

 this is terminated by a perpendicular cliff. In the vicin- 

 ity are evidences of volcanic action in the form of vol- 

 canic cones and solfataras of very recent origin. Fig. 87 

 is a section of the same. 



Now, there is abundant proof that this coast has slowly 

 sunk and risen again at least twenty feet, and that this 

 has all taken place certainly since Roman times, and 

 probably since 1200 A. D. The evidence is briefly as 

 follows : 1. The Starza consists of stratified material con- 

 taining recent Mediterranean shells. 2. The cliff which 



