10 PHYSICAL UROGRAPHY OF THE SEA. 



of mud and sand, which so many rivers continually carry along 

 with them into the sea. Thus at the mouths of the Nile, of the 

 Granges, and of the Mississippi, large alluvial plains have been 

 deposited, which now form some of the most fruitful portions of 

 the globe. The whole Delta of Egypt, Bengal, and Louisiana, 

 have thus gradually emerged from the waters. 



The volcanic powers, which once caused the highest mountain 

 chains to rise from the glowing bosom of the earth, are still 

 uninterruptedly active in changing its surface, and are gradually 

 displacing the present boundaries of sea and land, upheaving 

 some parts and causing others to subside. 



On the coast of Sweden, it has been ascertained that iron 

 rings fixed to rocks which formerly served for the fastening oi 

 boats are at present much too high. Flat cliffs on which, ac- 

 cording to ancient documents, seals used to be clubbed while 

 enjoying the warm sunbeam, are now quite out of the reach of 

 these amphibious animals. In the years 1731, 1752, and 1755, 

 marks were hewn in some conspicuous rocks, which after the 

 lapse of half a century were found to have risen about two feet 

 higher above the level of the sea. This phenomenon is confined 

 to part of the coast, so that it is clearly the result of a local and 

 slowly progressive upheaving. 



Whilst a great part of Scandinavia is thus slowly but steadily 

 rising, the shores of Chili have been found to rise convulsively 

 under the influence of mighty volcanic shocks. Thus after the 

 great earthquake of 1822, the whole coast, for the length of a 

 hundred miles, was found to be three or four feet higher than 

 before, and a further elevation was observed after the earthquake 

 of Feb. 21st, 1835. 



While to the north of Wolstenholme Sound, Kane remarked 

 signs of elevation, a converse depression was observed as he 

 proceeded southwards along the coast of Greenland, Esquimaux 

 huts being seen washed by the sea. The axis of oscillation 

 must be somewhere about 77° N. lat. 



At Keeling Island, in the Indian Ocean, Mr. Darwin found 

 evidence of subsidence. On every side of the lagoon, in which 

 the water is as tranquil as in the most sheltered lake, old cocoa- 

 nut-trees were undermined and falling. The foundation-posts 

 of a store-house on the beach, which the inhabitants had said 

 stood seven years before just above high-water mark, were now 



