ON EMBANKMENTS, PIERS^ HARBOURS, &C. 375 



SECTION XII. 



Embankments, Piers, Harbours, and gaining Land from 



the Sea. 



IN various sections of the present chapter, and particularly that 

 on Inundations, we have seen the dry land occasionally encroached 

 upon to a very considerable extent by the natural action of different 

 seas or rivers. In other instances, and particularly in the section of 

 a preceding chapter, which treats of the formation of new islands, 

 we have seen the dry land make similar encroachments upon the 

 surrounding beds of water. " In this manner the boundaries of 

 organized life are alternately extending and diminishing; in the 

 former instance sometimes thrown up all of a sudden by the dread 

 agency of volcanoes, and sometimes reared imperceptibly by the 

 busy agency _of corals and madrepores. Liverworts and mosses 

 .first cover the bare and rugged surface, when not a vegetable or 

 any other kind is capable of subsisting there, they flourish, bear 

 fruit, and decay ; and the mould they produce forms an appropriate 

 bed for the higher order of plant-seeds which are floating in the 

 breeze or swimming on the deep. Birds next alight on the new- 

 formed rock, and sow with interest the seeds of the berries, or the 

 eggs of the worms and insects on which they had fed, and which 

 pass through them without injury. Thus the vegetable mould be- 

 comes enriched with animal materials; and the whole surface is 

 progressively covered with herbage, shaded by forest trees, and ren- 

 dered a proper habitation for man and the domestic animals thai 

 attend upon him. 



** The tide that makes a desolating inroad on one side of a coast 

 throws up vast masses of sand on the opposite. The lygeum or 

 sea-mat weed, that will grow on no other soil, thrives here and 

 fixes it, and prevents it from being washed back or blown away. 

 Thus fresh lands are formed, fresh banks upraised, and the boister- 

 ous sea repelled by its own agency, and there are a variety of other 

 plants whose roots or ramifications have an equal tendency to fix the 

 quicksand, and produce the same effect: such, especially., as the 



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