88 EFFECTS OP FORESTS ON MARSHES. 



coming down by Bradley's mill, and so home, much pleased, notwith- 

 standing the little disagreeables, with our little excursion." 



In regard to the effects of the work of the beaver, it is remarked 

 by Marsh, " I am disposed to think that more bogs in the Northern 

 States owe their origin to beavers than to accidental obstructions of 

 rivulets by wind-fallen or naturally decayed trees ; for there are few 

 swan-ps in those States, at the outlets of which we may not, by 

 careful search, find the remains of a beaver dam. The beaver some- 

 times inhabits natural lakelets and even large rivers like the 

 Mississippi, when the current is not too rapid, but he prefers to owe 

 his pond to his own ingenuity and toil. The reservoir once con- 

 structed, its inhabitants rapidly multiply so long as the trees, and 

 the harvests of pond lilies and other aquatic plants, on which this 

 quadruped feeds in winter, suffices for the supply of the growing 

 population. 



" But the extension of the water causes the death of the neighbouring 

 trees, and the annual growth of those which could be reached by 

 canals and floated to the pond soon becomes insufficient for the wants 

 of the community, and the beaver metropolis now sends out 

 expeditions of discovery and colonization. The pond gradually fills 

 up, by the operation of the same causes as when it owes its existence 

 to an accidental obstruction, and when, at last, the original settle- 

 ment is converted into a bog by the usual processes of vegetable life, 

 the remaining inhabitants abandon it and build on some virgin brook- 

 let a new city of the waters." 



And he adds in a foot note : — " I find confirmation of my own 

 observation on this point (published in 1863) in the ' North West 

 Passage by Land,' of Milton and Cheadle, London, 1865. These 

 travellers observed ' A long cjiain of marshes formed by the damming 

 up of a stream which had now ceased to exist,' chap. x. In chap. xii. 

 they state that ' Nearly every stream between the Pembina and the 

 Attrabasca — except the large river M'Leod — appeared to have been 

 destroyed by the agency of the beaver,' and they question whether 

 the vast extent of swampy ground in that region ' Has not been 

 brought to this condition by the work of beavers, who have thus 

 destroyed, by their own labour, the streams necessary to their own 

 existence. 



" But even here nature provides a remedy, for when the process of 

 consolidation shall have been completed, and the forest re-established 

 upon the marshes, the water now diffused through them will be 



