26 TALKS ABOUT THE SOIL. 



each piece as it goes. In time the stream comes to 

 more level ground, and runs slower and slower. The 

 current, not being able to push the larger stones any 

 farther, leaves them all by themselves. As it goes 

 slower and slower, it is still weaker, and drops the 

 coarser sand, and then the finer sand. Lastly, the 

 finest dust suspended in the water must be dropped 

 in smooth beds of mud ; and the water flows away to 

 the sea quite clear, having left its loads behind in the 

 lowlands, and all correctly sorted out, the gravel 

 by itself in one place, the sand in another, the fine 

 mud in another. Running water is the great soil- 

 mover. It takes the broken fragments of rocks from 

 the hills, and transports the material to distant plains, 

 perhaps hundreds of miles away. The bits of rock 

 broken off by the cold in the White Mountains may 

 be transported by the Connecticut River, and left 

 as rich soft mud on the meadows about Hartford. 

 The yellow mud of the Mississippi may drift a thousand 

 miles across the continent, and lay the dust of Penn- 

 sylvania hills among the sugar- plantations of Louisiana. 

 The first rains that fell on the oldest primeval rocks 

 became the first soil-movers ; and the work has gone 

 on for countless centuries on centuries, precisely as we 

 see it going on to-day. Floods and storms may have 

 hastened the work. Mountains of volcanic dust may 

 have been swept away by a single storm, and scattered 

 over the plains for a hundred miles in every direction. 

 There is every reason to think, that, in the geological 

 past, the streams and rivers wore down and carried 



