AGEICULTURAL AND MATERIAL EESOUECES. 583 



River, are unsurpassed in the value of their water power, which can be 

 made uniform throughout the year by using the lakes tributary to these 

 streams for reservoirs. Probably much of the wooded portion of the coun- 

 try that was covered by Lake Agassiz will be cleared and used as farming- 

 land; while the waterfalls and rapids which abound on rivers within the 

 Archean part of the wooded district will become the sites of manufacturing- 

 villages and cities. 



VARIETY AND DISTRIBUTIOST OF THE SOILS. 



Over nearly the entire prairie district of Lake Agassiz and upon the 

 higher and more undulating or rolling country that stretches thence west- 

 ward, a sandy clay, often with some intermixture of gravel and occasional 

 bowlders, forms the soil, which has been colored black to a depth of 1 or 2 

 feet below the surface by decaying vegetation. The alluvial and lacustrine 

 beds, or the glacial drift, the same as the soil, excepting that they are not 

 enriched and blackened by organic decay, continue below, being usually 

 yellowish gray to a depth of 10 or 15 feet, but darker and bluish beyond, 

 as seen in wells. The glacial drift contains many fragments of Cretaceous 

 shale, magnesian limestone, granites, and crystalline schists; and its fine 

 detritus and the silty deposits carried into Lake Agassiz by its tributaries 

 are mixtures of these pulverized rocks, presenting in the most advantageous 

 proportions the elements needed by growing- plants. 



The till or glacial drift of this region is remarkably contrasted with 

 that of New England and the other Northern States westward to the Missis- 

 si2)pi River by its containing- a smaller proportion of bowlders, cobbles, or 

 com])aratively small rock fragments and gravel. On an average the surface 

 of the till in this southwestern part of the area of Lake Agassiz has prol^a- 

 bly not more than one-twentieth as many bowlders as the average in the 

 States farther east. They are so few that they present no obstacle to 

 the cultivation of the soil, except on the occasional morainic belts, where 

 bowlders are plentifid, often strcAving the ground upon limited tracts, 

 which usually are knoUy and hilly. These tracts can not be profitably 

 subjected to tillage, l)ut have generally a fertile soil and afford excellent 



