58 UPRAISED STRATA IN SWEDEN AND NORWAY, CHAP. III. 



century to century, and the insensible rate of variation in 

 the geographical distribution of organic beings in our own 

 times, we may presume that an extremely lengthened period 

 was required, even for so slight a modification in the range 

 of the molluscous fauna, as that of which the evidence is 

 here brought to light. There are also other independent 

 reasons for suspecting that the antiquity of these deposits 

 may be indefinitely great as compared to the historical 

 period. I allude to their present elevation above the sea, 

 some of them rising, in Norway, to the height of 600 feet or 

 more. The upward movement now in progress in parts of 

 Norway and Sweden extends, as I have elsewhere shown,* 

 throughout an area about 1000 miles north and south, and 

 for an unknown distance east and west, the amount of eleva- 

 tion always increasing as we j^roeeed towards the North 

 Cape, where it is said to equal five feet in a century. If w^e 

 could assume that there had been an average rise of two 

 and a half feet in each hundred years for the last fifty cen- 

 turies, this would give an elevation of 125 feet in that period. 

 In other words, it would follow that the shores, and a con- 

 siderable area of the former bed, of the North Sea, had been 

 ujilifted vertically to that amount and converted into land 

 in the course of the last 5000 years. A mean rate of con- 

 tinuous vertical elevation of two and a half feet in a century 

 would, I conceive, be a high average; yet, even if this be 

 assumed, it would require 24,000 years for parts of the sea- 

 coast of Norway, where the post-tertiary marine strata 

 occur, to attain the height of GOO feet. 



* Principles, 9th ed. ch. xxx. 



