THE QUATERNARY PERIOD 457 



regions is on the average a better soil than the residual sandy 

 clays which are produced by the ordinary weathering of many 

 rocks. In some places, notably in parts of New England and 

 eastern Canada, however, the till contains so many bowlders 

 that cultivation of the soil is very laborious. Among the best 

 harbors in the United States are the glacial fiords and bays of 

 the New England coast. These facilities early helped to lead 

 the people of the region to engage in fishing and to become 

 the best seamen and shipbuilders of the country. 



The general derangement of rivers by the ice sheets hindered 

 inland navigation in a measure, but at the same time it con- 

 ferred large benefits in the form of available water power from 

 the many falls and rapids. The abundance of these falls 

 near the centers of trade in northeastern United States has 

 assisted in making that region a great manufacturing district. 

 As the progress of invention makes it possible to transmit 

 electric power over longer and longer distances, these falls 

 will be used more extensively ; and as the fuel resources of 

 the country are gradually depleted, more and more depend- 

 ence will be placed on electricity from water power. The 

 glaciated regions are thus likely to retain their interest and 

 importance in the manufacturing industry. 



THE GLACIAL EPOCH OUTSIDE OF THE ICE SHEETS 



In the rest of the United States and in other continents the 

 events of the Quaternary period were much like those of the 

 preceding Tertiary. By the erosion of running water, pla- 

 teaus were being cut into hills and mountains, winds were carv- 

 ing out the softer rocks in the deserts, and waves were eating 

 back the rocky coasts. Along low-lying plains and river bot- 

 toms, gravel, sand, and mud were strewn ; while the waves and 

 winds built barriers and sand dunes along the edges of the 

 shallow seas. 



There is a decided contrast between the conditions and ap- 

 pearance of the recently glaciated and the unglaciated parts of 

 the land (Figs. 474 and 475). Over much of the region where 



