THE ROMANCE OF A RIVER 



163 



"AT LOW WATER SANDBANKS ARE 

 The Mawddach from Panorama 



and the Amazon bring down so 

 fine mud in suspension that the 

 coloured for many miles from the 

 The Rhone is fed by melting 

 glaciers, and owing to the 

 presence of suspended rock 

 flour, is milky white until it 

 clears itself on traversing the 

 Lake of Geneva. We cannot 

 conceive the vast quantities 

 of waste which the great 

 rivers of the world are con- 

 stantly depositing in the oceans. 

 What we must keep in mind 

 is the fact that all this comes 

 from the land. It may be 

 stated as a simple rule that 

 while the land gives much 

 to the sea, the sea gives 

 nothing to the land. 



Rivers play an important 

 but not the principal nVf in 

 ■excavating the solid rocks. 

 but they are pre-eminent as 

 agents of transport. The ex- 

 cavating power of a river de- 

 pends on two factors — the 

 hardness of the rocks and the 

 quickness of fall. We have 

 already seen that when tra- 

 versing hard rocks the stream 

 is confined to a narrow channel 

 and cuts a gorge with almost 

 vertical sides, and when it 

 flows through softer material 

 it tends to widen its valley 



much 

 sea is 

 coasts. 



Tims even at a distance 

 in looking over a valley 

 we can tell at once the 

 nature of the ground. 



It is obvious, too, that 

 the more rapid a stream 

 is the greater power it 

 will exercise in deepen- 

 ing its channel. If two 

 streams have their origin 

 at the same altitude, 

 and one takes a short, 

 direct route to the sea, 

 and the other follows a 

 longer and less direct 

 course, the shorter, 

 owing to its more rapid 

 fall, will cut back its 

 channel more quickly 

 than the longer one. 

 Thus we come to see that some streams 

 are possessed of certain advantages 

 even at their l)irth which enable them to 



LEFT HIGH AND DRY 

 Walk, Barmouth. 



THE STREAM JS CONFINED 1 A NAKKv.' 

 AND CUTS A GORGE" 

 A view on the Lowther. 



