236 FIRST YEAR COURSE -IN GENERAL SCIENCE 



from othe"r hills; and a mighty river carries it all to the 

 sea. 



256. The Load of Rivers.- There is much besides water 

 that is being carried to the sea by the -rivers. The load of a 

 river consists of dissolved mineral matter and rock waste 

 in the form of mud and sand. All this has been gathered 

 from every part of the land whence water has flowed into 



FIG. 124. SURFACE SPRING 



i represents impervious rock; p, h, porous rock; c, loose earth; s, a hill- 

 side spring; r, a river bed. 1. What is the source of water flowing out at 

 sf 2. Does it come out with great pressure? Why? 3. If a wall were 

 built around the spring, how deep could the water be in the basin, as judged 

 by this diagram? 4. Describe the stream that would flow from s to r. 



the river. The Mississippi River, which carries a greater load 

 than any other river in the United States, gathers it from the 

 mountains of Montana, the forests of Minnesota, the farms 

 of Kentucky, and other lands along its course. 



It is hard to realize how much solid material a river carries. 

 It deposits its load on the banks, in the bed of the stream, and 

 at the mouth. A swift current carries much material, coarse 

 and fine, and deposits none. A slower current drops coarse 

 material and carries only the finer. When a river enters a 

 lake or the sea and its current is checked, it usually drops 

 the last of its load. Whether the material settles here or 

 is carried farther and distributed by currents and waves of 

 the sea, depends upon the form of the coast and the direc- 

 tion of currents and prevailing winds. The current of the 

 Amazon pushes' out to sea and carries some of its load three 

 hundred miles from land, as is indicated by the muddy color 

 of the ocean. 



