136 



IGXEOUS AGENCIES. 



which increases as we go north until it attains a maximum of five to 

 six feet per century. These observations were made under the direc- 

 tion of the Swedish Government by means of permanent marks made 

 at the sea-level, and examined from year to year. That similar 

 changes have been in progress for thousands of years, and have greatly 

 increased both the height and the extent of these countries, is proved 

 by the fact that old sea-beaches, full of shells of species now living in 

 the neighboring seas, are found fifty to seventy miles inland, and 100, 

 200, and even 600 feet above the present sea-level. In some places, the 

 country rock, when uncovered by removing superficial deposit of beach- 

 shells, is found studded with barnacles like those which mark the 

 present shore-line (Jukes). 



The rising area is about 1,000 miles long north and south, and of 

 unknown breadth It may embrace a considerable portion of Russia. 

 Lyell estimates the average rate as not more than two and a half feet 

 per century. At this rate, to rise 600 feet would require 24,000 years.* 

 Similar raised beaches are found in nearly all countries. We give 

 these as examples of an almost universal phenomenon, which will be 

 again more perfectly described in the chapter on the Quaternary. 



Greenland. — For obvious reasons, evidences of elevation are much 

 more conspicuous than evidences of depression. One of the best-ob- 

 served instances of the latter is that of the coast of Greenland. This 

 coast is now sinking along a space of 600 miles. Ancient buildings 

 on low rock-islands have been gradually submerged, and experience 

 has taught the native Greenlander never to build his hut near the 

 water's edge. 



the deltas of the Mississippi, the 

 large rivers, there are unmistakable 

 evidences of gradual depres- 

 sion. These evidences are 

 fresh- water shells, and planes 

 ;e elEE F~ j ^[J^ of vegetation, or dirt-beds, 

 far below the present level of 

 the sea. A section of the 

 delta deposits of the Missis- 

 sippi River reveals the fact 

 that these deposits consist of 

 river sands and clays, s cl, 

 (Fig. 113), containing fres U- 

 water shells, with now and 

 then an intercalated stratum of marine origin, I, containing marine 

 shells, and at uncertain intervals distinct lines of turf ox vegetable soil, 



Deltas of Large Rivers.— In 



Ganges, the Po, and many other 



Lyell's Antiquity of Man, p. 58. 



