16 SOILS 



to the action of moving water. Moving water has 

 been given the gigantic task of world levelling, and 

 is working at it industriously and successfully. 

 The mountains, hills and knolls are worn away; 

 water carries the particles down the valleys and 

 deposits them as soil. Lakes and ponds are being 

 filled with soil washed from higher land. The 

 flat lands about the lakes and streams are made 

 mostly of soil worn away from the surrounding 

 highlands. The streams carry great quantities 

 of soil and deposit it in the shallows and bends. 

 The coarser and heavier materials, as gravel and 

 sand, are deposited first and the finer material, as 

 clay, is deposited only when the current becomes 

 sluggish. At the mouths of streams, where the 

 current is sluggish, a "delta" is often formed by 

 the accumulation of soil carried down by the 

 streams. It has been estimated that the amount of 

 soil carried to the Gulf of Mexico every year by the 

 Mississippi River would cover a square mile of 

 territory 268 feet deep. At this rate, the American 

 continent might be reduced to sea-level in four and 

 one-half million years. This is but a small pro- 

 portion, however, of the total amount of soil that 

 these rivers carry, for most of it is left along 

 their banks. According to reliable measurements, 

 England is 550 square miles smaller now than at 

 the time of the Norman Conquest, owing to the 

 soft chalk and clay shores being crumbled away 

 by waves. 



Every stream is constantly changing its course; 

 many a valley farmer has had the river take away 

 a large slice of his farm and give it to his neighbour 

 down stream. Brooks states that within a genera- 

 tion the Connecticut River has gradually taken 

 several hundred acres of rich meadow land from 



