BRITISH MOSSES. 53 



In some Irish bogs fir, oak, and yew, and rarely elm, 

 have been found. 



What is the cause of the disappearance of these ancient 

 forests one after the other? To this question various 

 answers have been proposed. 



The Eomans, it has been suggested, in their inroads, cut 

 ways through the forests and laid waste the land. But, 

 wide as was the spread of the wings of the Roman eagle, 

 the phenomenon in question is of far wider extension. 

 They never conquered Denmark, or Norway, or Ireland, or 

 the islands of Scotland : in Scotland, and even hi England, 

 their operations could never have covered the whole 

 country ; and as regards some of our Peat Mosses, we 

 know that they must have existed long before the Roman 

 invasion ; for at least on the borders of Sedgmoor we have 

 traces of their using peat for fuel as it is used there at the 

 present day. 



Still humbler agents have been invoked, in the suppo- 

 sition that the beaver and other rodents were the authors 

 of the destruction of the forests. So far as I can judge, 

 the cause suggested seems inadequate to the effect. 



Again, changes hi climate have been suggested. But, 

 although there may be some evidence from the succession 

 of the trees of a gradual amelioration in the climate, 

 we know of no evidence of changes of so sudden and 

 violent a character as would destroy the existing forests 

 over large areas. Moreover, with few exceptions, the 

 trees of the destroyed forests are such as are now found 

 wild, or will grow easily hi the spots where they lie 

 buried. 



