REVIEv^'S — CLIMATOLOGY OF THE UNITED STATES. 31 



of California are mainly controlled by the mountains near them, and if shut from 

 the sea have arid climates, and, perhaps, a denuded, sandy, or alkaline surface ; 

 ■when if open to sea influences the reverse conditions prevail. These remarks apply 

 more particularly to Oregon and the coasts north of the 35th parallel, than else- 

 where, as the coast of Lower California is arid at all exposures." pp 88, 89. . 



This climatological division is again insisted on in tlie opening 

 paragraph of the following chapter, descriptive of the general 

 character of the Eastern United States. 



" It is necessary to make a distinction of a very decided character between the 

 parts of this continent separated by the Rocky Mountains, though the idea of this 

 distinction has hardly yet entered into the received views of the Iforth Americau 

 climate. It is still described under the characteristics vi^hich beiong only to the 

 area east of the great plains, and the homogeneous character belonging to much 

 of this great extent of surface is that recognized in Europe as the North Ameri- 

 can climate. Now that we have found this to differ so extremely from the interior 

 and Pacific districts, it is necessary to describe it separately and to designate it aa 

 the eastern area of the United States. 



So recently as the production of Guyot's able work on comparative physical 

 Geography (Guyot's Earth and Man), the distinction made between the old world 

 and the new was to assign to the new oceanic, and to the old world continental 

 climates ; the prevailing character of the Eastern States and the Mississippi Val- 

 ley being taken as the type of the whole country. The great expanse of these 

 plains gave reason for this distinction, in the then unknown condition of the in- 

 terior and Pacific coast, but it is now clear that the proportion of arid and conti- 

 nental districts and climates is as great here as in the old world. The position of 

 the plains esposed to oceanic influences is reversed, however, and instead of the 

 extensive low areas belonging to the west of Europe our western coast is very 

 narrow, and the Mississippi plain is, to some extent, the equivalent of the European 

 plain. 



But the climate of the Mississippi Valley or plain, and of the eastern side of 

 the continent generally, is not oceanic strictly ; and it differs radically from the 

 oceanic climates of the west of Europe. It has its equivalent only in a similar 

 continental position, or in China ; which is, unfortunatly, too little known to aid 

 the illustration much. As a whole, the North American continent differs little 

 from the old world, except in the comparative areas embraced by the several 

 divisions. Our oceanic districts on the west are very narrow and unimportant 

 compared with the immense aud fertile areas of like position and climate in 

 Europe ; our interior and extreme districts are differently placed from those of 

 Asia, but in other respects they differ little ; our eastern areas, which are properly 

 neither interior nor oceanic, are comparatively larger and more important because 

 of the existence here of a great interior plain opening southward to the tropical 

 heat and moisture, and partaking to some extent of tropical peculiarities 



The early distinction between the Atlantic States and the Mississippi Valley 

 has bsen quite dropped as the progress of observation has shewn them to be es- 

 sentially the same, or to differ only in unimportant jjarticulavs. It is difficult to 

 designate any important fact entitling them to separate classification ; they are 

 alike subject to great extremes and to the same extremes, they both have marked 



