68 



WAITING IN THE WILDERNESS 



gray granite from Pike's Peak, yellow lava from 

 Yellowstone, red sandstone from many states, 

 and glaciated gravel from Canada. Then there 

 are volcanic dust, shells of water life, and the 

 bones of animals. Along with these in solutioi 

 the water also carries minerals and acids, lime, 

 salt, and soda. The caves of Kentucky wen 

 made by water dissolving and washing away th< 

 lime. Altogether millions of tons each yeai 

 are carried into the sea by the Mississippi, 

 There are dozens of other large rivers each carry- 

 ing its burdens into the sea. Probably the 

 rivers of the world move as much freight eacl 

 day in the way of washed material as all th< 

 railroads move of their kind of freight. 



Big deltas of this sediment form at the moutl 

 of most rivers. No deltas are found at the moutl 

 of the mighty Amazon or the mouth of th< 

 Thames River. Here the swift ocean current! 

 sweep the material away and scatter it over th< 

 bottom of the sea. Although the Hudson an< 

 the Susquehanna rivers are daily emptyin] 

 countless tons of silt and sand into the sea, n< 

 delta shows. The mouths of these rivers wen 

 recently "drowned" that is, deeply sul 

 merged, by the sinking of the earth aroun< 

 and beneath their mouths. The water at theii 

 mouths is at present too deep for delta materi; 

 to show, but deltas are building. 



