STREAMS WEAR AWAY THE LAND 



363 



been washed into rivers. Many a farmer dreads the heavy rain 

 which washes or erodes away his top soil and leaves ruts and 



FIG. 229. A gully worn out by erosion. 



gullies on his farm (Fig. 229). Streams and rivers flow toward 



the sea and carry with them sand, pebbles, and debris. When 



rocks are exposed along streams, they weather and crumble 



into fragments which slowly 



slide down into the water 



flowing at the foot of the 



rocks. Rocks and stones, 



dislodged by rain, wind, and 



animals, fall into streams, 



loose soil slips slowly down 



hills and also becomes part 



of the stream. A river is 



loaded by these materials, 



and it adds to this load by 



picking up loose materials 



from its bed and banks. 



All of this load the river FlG - 230. These rocks are rolled down- 



stream at high water. 



carries to the sea. Sand and 



loose soil particles are carried in suspension as sediment buoyed 



up by constantly eddying currents. Substances dissolved from 



