DESEET SANDS 343 



Kong mountains) ; at another place it is the Arabian coast 

 range, Lebanon, and the Beluchi hills ; at a third, it is the 

 Himalayas and the Chinese heights that intercept and 

 precipitate all the moisture from the clouds. But, from 

 whatever variety of local causes it may arise, the fact still 

 remains the same, that all the great deserts run in this 

 long, almost unbroken series, beginning with the greater 

 and the smaller Sahara, continuing in the Libyan and 

 Egyptian desert, spreading on through the larger part of 

 Arabia, reappearing to the north as the Syrian desert, and 

 to the east as the desert of Rajputana (the Great Indian 

 Desert of the Anglo-Indian mind), while further east again 

 the long line terminates in the desert of Gobi on the Chinese 

 frontier. 



In other parts of the world, deserts are less frequent. 

 The peculiar combination of circumstances which goes to 

 produce them does not elsewhere occur over any vast area, 

 on so large a scale. Still, there is one region in western 

 America where the necessary conditions are found to per- 

 fection. The high snow-clad peaks of the Rocky Moun- 

 tains on the one side check and condense all the moisture 

 that comes from the Atlantic ; the Sierra Nevada and the 

 Wahsatch range on the other, running parallel with them 

 to the west, check and condense all the moisture that 

 comes from the Pacific coast. In between these two great 

 lines lies the dry and almost rainless district known to the 

 ambitious western mind as the Great American Desert, 

 enclosing in its midst that slowly evaporating inland sea, 

 the Great Salt Lake, a last relic of some extinct chain 

 of mighty waters once comparable to Superior, Erie, and 

 Ontario. In Mexico, again, where the twin ranges draw 

 closer together, desert conditions once more supervene. 

 But it is in central Australia that the causes which lead to 

 the desert state are, perhaps on the whole, best exemplified. 



