CONTINENTS; OCEANS 



193 



some period a region which had been dry land was sub- 

 merged; then later it was again elevated. Some continents 

 have lost by slight subsidences along their borders. After 

 hundreds of years such changes have brought the shore line 

 farther inland than it was at a former time in history. 



A curious example of successive falling and rising of the 

 borders of a continent is found at Pozzuoli, Italy. A temple 

 built near the sea long 

 before the Christian era 

 was afterward partly 

 submerged as the land 

 sank. There is no 

 written history of this 

 event and none is 

 needed, for the story 

 is told on the stone 

 pillars of the temple. 

 Upon the stone many 

 feet above the level of 

 the sea, which is now 

 quite distant from the 

 temple, are marks made 

 by sea shells that had 

 grown upon the pillars. 

 They were as securely 

 fastened there as barna- 

 cles are on rocks of 



the shore to-day, raindrops on half dried mud. It also tells 



These shells were below tha * an animal with a foot resembling a 



bird s walked over the mud. 



water when they were 



parts of living animals; therefore their present position 



shows the re-elevation of the coast. 



An evidence of continued wearing away by waves is seen 

 in the diminishing size of the island of Helgoland in the 

 North Sea. In the year 800 it had a circumference of one 



FIG. 100. .FOSSIL RAINDROP 

 IMPRESSIONS 



This piece of shale is an old weather 

 report. It tells of a short shower of heavy 



