Natural History of the Beaver in Canada 349 



beaver's accomplishments. Its object is the formation 

 of an artificial pond to ensure a permanent waterway to 

 the entrances of their lodges and burrows. Like the 

 lodge it begins in a small way and is added to and re- 

 paired from year to year. In course of time the ponds 

 become so large as to flood the surrounding lowlands, 

 thus killing the trees and giving rise eventually to the 

 beaver meadows. Morgan's "Great Dam at Grass Lake" 

 was the most remarkable of the many examples that 

 came under his notice. It was 260 feet long, measured 

 with a tape line along the crest ; 6 feet high at the centre 

 of the great curve, with a slope of 13 feet on the lower 

 face. 



By a singular coincidence it happened that about the 

 same time that Lewis Morgan was assisting in the ex- 

 ploitation of the iron mines at Marquette, Alexander 

 Agassiz was developing the copper mines at Calumet in 

 another part of Michigan. He also turned his attention 

 to the beaver and intended to write up his observations 

 but was forestalled by Morgan, whose work he gener- 

 ously appreciated. An interesting letter from Agassiz 

 to Mr. Morgan, written in 1868, shortly after the publi- 

 cation of the latter 's book, is preserved in the recently 

 published "Letters and Recollections of Alexander 

 Agassiz," edited by G. R. Agassiz (Boston, 1913). 



The beaver meadows attracted the notice of Sir 

 Archibald Geikie. Describing, in his "Geological 

 Sketches" (New York, 1882, p. 201), an excursion to the 

 Uintah Mountains, to the south of the Bad Lands of 

 Wyoming, he says : ' ' No sooner had we reached the 

 valley bottom than abundant traces of vanished glaciers 

 made their appearance in the form of perfect crescent- 

 shaped moraine mounds thrown across the valley* * * 

 Each mound of rubbish had served as a more or less 

 effective barrier in the pathway of the stream, ponding 

 back its waters into a lake that had eventually been con- 

 verted into a meadow. But far more effective than the 

 glacier-made dams had been those of the beaver. The 



