396 HISTORICAL GEOLOGY. 



and the old river-beds are now found on the top of the 

 present divides. 



Phenomena similar to those discussed are found in 

 Europe and in all other high-latitude regions, both north 

 and south of the equator. 



Some General Results of Glacial Erosion. 



1. Fiords. If one examines an accurate map of coast- 

 lines, he will see that, in the region affected by Quater- 

 nary oscillations, there is a bold, deeply dissected coast- 

 line. In Norway these deep inlets are called fiords, 

 and therefore this structure, wherever found, is called 

 fiord-structure. We find it strongly marked in Green- 

 land and in Alaska. This structure, in Norway, is 

 partly due to the action of waves (page 45), but also, and 

 mainly, to the submergence of old glacial valleys. In 

 Greenland and Alaska they are still partly occupied by 

 glaciers. 



2. Lakes. Examine your map of North America. 

 See how the whole northern part is dotted over with lakes, 

 while the southern part is almost destitute of them. See 

 also that the lake-area is also the area of the drift. Now, 

 although lakes may be formed in many ways, and exist in 

 all parts of the world, yet undoubtedly the small lakes at 

 least, which are so thickly sprinkled over the drift-region, 

 have been produced by glacial agency. 



There are several ways in which glacial lakes were 

 formed : 1 . They are sometimes rock-basins, scooped out by 

 glacial erosion. 2. They are often formed by the damming 

 of drainage waters behind old terminal moraines. These 

 two kinds are thickly strewed all over high mountain- 

 regions in the pathways of old glaciers. Standing on the 

 crest of the Sierra, fifty may sometimes be counted at 

 one view. 3. In flat regions, as in northern Minnesota 

 and British America, they are simply hollows produced 



