294 



SOILS. 



abundant rainfall between the Mississippi river and the At- 

 lantic coast is due to the moist winds coming from the warm 

 waters of the Gulf of Mexico and Caribbean sea, whose access 

 is not interfered with by any cross-ranges of mountains. But 

 the Great Plains lying between the Mississippi and the Rocky 

 Mountains are not within the sweep of the Gulf winds, whose 

 trend is SW to NE; while they are equally out of reach of 

 moisture from the Pacific, all that having been successively de- 

 posited on the intervening mountains; hence their deficient 

 rainfall. 



Northward of the temperate zone the rainfall generally de- 

 creases as we approach the arctic regions ; except where the in- 

 fluence of warm ocean currents to windward creates com- 

 paratively local exceptions, as in the case of Norway and 

 Alaska. 



* 



Fie. 52. Composite Curve showing distribution of Rainfall in Europe, Africa and America pro- 

 jected on 100 Meridian \V. L. 



The general Distribution of Rainfall on the globe is well 

 shown in the annexed diagram, which is copied by permission 

 of the author from his treatise on the " Evolution of 

 Climates," l and represents the mean deduced from data given 

 in the Atlas of Meteorology by J. G. Bartholomew. It is a 

 composite curve derived from the consolidation of four curves 

 showing the distribution of rainfall, viz, on the meridians of 



1 " The Evolution of Climates"; by Marsden Manson, July, 1903; also Amer 

 Geologist, Aug.-Oct. 1897. 



