CHAPTER VI 

 LAKES AND SHORES 



GENERAL FACTS CONCERNING LAKES 



Definition. A lake is an inland body of standing water larger 

 than a pool or a pond; but the term is also sometimes applied to 

 the widened parts of rivers (Fig. 106), and to bodies of water which 

 lie along coasts, even when they are in direct connection with the 

 sea (Fig. 148). Most lakes are fresh, but a few, like Great Salt 

 Lake and the Dead Sea, are much more salty than the sea itself. 



Distribution of lakes. 1. Lakes occur in most latitudes, but 

 they are more abundant in high latitudes than in low, because the 

 former- have been more extensively glaciated than the latter. 

 2. Lakes are abundant in some mountains, especially in those which 

 have been glaciated in recent times. 3. Lakes occur along some 

 rivers. Outside of glaciated regions, they are common only along 

 streams which have low gradients and wide flats, where the origin 

 of the lakes is connected with the changing of the river channel 

 (PL XVII, p. 64). 4. Lakes are rather common along coasts Fig.) 

 1, PL XXXVIII, p. 133 and Fig. 148), though many coasts are with- 

 out them. Coastal lakes stand in no apparent relation to latitude, 

 and their levels are nearly or quite the same as that of the sea. 

 5. Lakes are found on low lands near the sea in some places, as in 

 Florida, where they are as abundant as in the glaciated parts of 

 the United States. 6. Lakes occur on some plateaus even where 

 there has been no glaciation. Examples are found in the great 

 lakes of central and southern Africa, and there are numerous 

 shallow lakes on the Great Plains (plateaus) of the United States, 

 even where the climate is dry. 7. Lakes occur in a few other situ- 

 ations, as in the tops of some volcanic mountains, and in mountain 

 valleys where landslides or lava-flows have made temporary dams. 



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