A WELSH ROADSIDE. . 151 



bossed surfaces of the native rock worn by 

 the glaciers which heaped up these refuse- 

 piles roches moutonndes, as they call them in 

 Switzerland perfect domes of bare stone, 

 even now sharply grooved and marked with 

 the striae scratched upon them by the super- 

 incumbent ice-stream. 



It is impossible to avoid noticing that the 

 walls are very much thicker than they need be 

 for any practical purpose ; indeed, in some 

 places they are as much as four or five feet 

 broad. The truth is, such walls are rather a 

 simple way of getting rid of the boulders 

 than a protective margin to the fields. In 

 trying to cultivate these glacial slopes, the 

 first thing to do is to weed out the surface 

 boulders ; and the easiest plan of doing so is 

 to pile them up all round the stubbed portion 

 of the field. The thickness of the wall 

 depends upon the number of the boulders. 

 Where they are many the field is small and 

 the wall big ; where they are few the field is 

 larger and the wall not quite so clumsy- 



