DEPRESSIONS IN THE EARTH'S SURFACE. 157 



is possible thus to create an inland sea larger than the 

 Caspian. 



What the effect of inundating a large portion of 

 the desert region of Northern Africa might be is open 

 to speculation on the part of those who take an in- 

 terest in problems of mammoth proportions. The 

 contemplated sea would be too shallow for naviga- 

 tion ; and the evaporation from such an expanded 

 surface would render the water salter than the sea, 

 and thus become destructive to organic life, enforcing 

 the question, what advantage a barren sea can have 

 over sterile lands. Besides, it is now practicable to 

 bore artesian wells in rainless districts of country, and 

 bring to the surface sufficient fresh water to irrigate 

 arid wastes, making " the desert rejoice, and bloom as 

 the rose." 



Australia has a depression all through its center, 

 its general outline being compared to a dinner plate, 

 the rim on the border keeping out the ocean. In 

 places there exists a shore range of mountains ; and 

 in the south-western portion of the great island, is a 

 small river system sustained by rains and melting 

 snows. The Murray River, when full, is navigable for 

 some distance inland, yet Lake Torrens is little better 

 than a brackish lagoon, and is below sea level, though 

 it once communicated with Spencer Gulf. In droughty 

 seasons, and nearly all are such, the rivers which tind 

 a place on maps dwindle to mere " water holes," or 

 occasional basins. The Murray has been known to 

 shrink to a chain of pools with no water flowing be- 

 tween them. 



South America, like other large countries, has 

 mountain ranges, great rivers,' and desert tracts. In 

 the latter are numerous salt lakes, brackish lagoons, 



