THE CRUST OF THE EARTH. 



119. Similar swellings and depressions of the land have been 

 manifested elsewhere. Thus, for four centuries, the western 

 coast of Greenland has been continually sinking through an 

 extent of 600 miles north and south. Ancient buildings, as well 

 upon the low islands of the coast as upon the mainland, have been 

 gradually submerged, and the removal to considerable distances 

 inland of various establfshments which formerly existed upon the 

 coast, has been rendered necessary. Similar sinkings of the surface 

 have been manifested in certain islands of the Southern Ocean, 

 especially in the Indian Archipelago. 



120. It would even appear, from a comparison of the observa- 

 tions of Messrs. Boussingault and Humboldt, separated by an 

 interval of thirty years, that the whole continent of South 

 America is gradually sinking, and, if this process be continued, 

 at some distant epoch it may even be submerged. The observa- 

 tions referred to show that the altitudes of the Andes at the 

 epoch of the observations of Boussingault were less than those 

 given by the anterior observations of Humboldt; and these 

 results are confirmed by the fact that the snow-line in this 

 range of mountains has, in the interval referred to, apparently 

 risen. 



121. An interesting modern example of the subsidence of a con- 

 siderable tract of country, clothed with forests, the trees remain- 

 ing erect, although submerged beneath a river which still flows 

 over them, is described by a late American writer, and will 

 serve to illustrate these remarks. The whole district, from 

 the Rocky Mountains on the east, and the Pacific Ocean on the 

 west, and from Queen Charlotte's Island on the north, to Cali- 

 fornia on the south, presents one vast tract of volcanic formation. 

 Basalt both columnar, and in amorphous masses, veins, and 

 dykes everywhere occurs, and craters of extinct volcanoes are 

 still visible. Elevations and dislocations of the strata have taken 

 place on an immense scale ; and successive beds of basalt, amyg- 

 daloidal trap, and breccia, prove the alternation of igneous action 

 and periods of repose. Within a few miles of the falls of the 

 river Columbia, and extending upwards of twenty miles, trees are 

 seen standing in their natural position, in a depth of water from 

 20 to 30 feet. The trees reach to high or fresh- water mark, which 

 is 15 feet above the lowest level of the tide ; but they do not 

 project beyond the freshet rise, above which their tops are decayed 

 and gone. In many places the trees are so numerous, that "we 

 had to pick our way with the canoe, as through a forest. The 

 water of the river was so clear, that the position of the trees could 

 be distinctly seen, down to their spreading roots, and they are 

 standing as in their natural state, before the country had become 



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