120 THE LAKE-BASINS OF IARCONN AUGHT. 



some of these lake-basins. Against it is the fact, that 

 although the beaver is known to have been an in- 

 habitant of Wales during the historic period, yet we 

 have been unable to find in the Irish annals any re- 

 cord of its existence. 1 



The great characteristic of the larconnaught lakes 

 are their " rock-basins." Such basins Professor 

 Ramsay seems to believe have been formed by ice 

 action, but of this theory Lyell writes, " It appears 

 . . . that the abrading _action of ice has formed some 

 mountain tarns and many moraine lakes, but when 

 it is a question of the origin of larger and deeper 

 lakes, ... it will probably be found that it has 

 played a subordinate part in comparison with those 

 movements by which the changes of level in the 

 earth's crust are gradually brought about." 2 



"We, however, would go even further than this 

 eminent geologist, and suggest that, unaided by the 

 other great denudants, and also by cracks, fissures, 

 and faults formed during the movements in the 

 earth's crust, ice is incapable of eroding out rock- 

 basins. 



In larconnaught, not only is meteoric abrasion 



1 There does not appear to be any real native Irish word for beaver. 

 In O'Reilly's Dictionary we find " Dobkran-leasleatkan, a beaver," but 

 he seems to have taken this from the Scotch Gaelic, as no mention of 

 beaver is known in any Irish MS. DoWiran means water-animal, and 

 leasleathan broad-tailed. The "Welsh for beaver is similar, namely, 

 " llostlydan," broad tail. 



2 " Student's Elements of Geology," p. 164. 



