126 



ETON NATUEE-STUDY 



parts of the road into the gutter. Instead, now, of a road, imagine 

 a mountain chain, and you will at once realise how streams rise on 

 either side of the ridge, and wash down the soil into the plains on 

 either side : nay more ; each of the little rivulets may often be seen 

 to be an exact copy of a very great river, consisting first of many 

 tributaries joining to form one which eventually breaks up into 



From a photograph by Charles Welch. 



FIGURE 118. A valley showing the windings of the river which made it. 

 The "Happy Valley," Mourne Mountains. 



several, and runs through a delta of sand. Just as the rivulets 

 tend to level the road and gradually wash it down into the gutters, 

 so the ultimate action of streams is to cut down and level all uprising 

 ground and carry the detritus to the sea. Then again, some roads 

 are paved with cobbles in the middle. The action of the rain will 

 affect the sides of the road more than the centre, causing the cobbles 

 to stand up, perhaps an inch or two, above the rest of the surface, so 



