North Wales. 401 



Bay. This I shall presently prove, for having brought 

 our ice so far south, it is now time to explain the part 

 played by the mountains of Wales in this glacial 

 history. 



When glaciers first began to form among the moun- 

 tains of the Highlands of Scotland, from 200 to 300 

 miles north of Wales, though the heights of the latter 

 region may have been far more snowy than they ever 

 are now, yet at first it is probable that the snow did not 

 continue through the year, and therefore no glaciers 

 were formed. But in time, as the great glaciers ad- 

 vanced, and the cold increased and snow in North W T ales 

 became perennial, then glaciers began to be formed, 

 first in the high valleys in the upper recesses of the 

 mountains ; and as the climate and precipitation of snow 

 grew more severe, these glaciers must have waxed in 

 size, till at length they filled all the valleys, and in- 

 truded on the plains and low undulating grounds be- 

 yond. How far south they extended from the moun- 

 tains of Merionethshire I do not know, but probably 

 the ice-flow went far into South Wales. Neither is it 

 possible to say how far these early glaciers of Snow- 

 donia stretched across the broad undulations of Ang-le- 



o 



sea, for, if they did so, the marks that they made were 

 afterwards entirely obliterated by the onward march of 

 the great northern glacier which I have already de- 

 scribed, and which I have no doubt extended southward 

 into St. Greorge's Channel. In aid of this statement I 

 would quote the opinion of the Keverend M. Close, and 

 the later observations of Professor Hull. The central 

 plain of Ireland forms a great basin, surrounded by the 

 broken mountains of the south from Kerry to Wicklow, 

 and of the west and north-west from Galway to Donegal, 



D D 



