PERIODICAL LITERATURE 



917 



The types of the great Intcr-moimtain Plateau province are of a 

 transitional character. As a whole, the dominant characteristic of the 

 rainfall distribution west of the Rockies is the cold-season maximum. 

 On the plateau we find a combination of the marine rainfall region 

 of the Pacific Coast and the continental region of the interior. 



Two well-defined types, one in the north, one in the south, are 

 recognized. The North Plateau type shows a winter maximum of 

 only 2 inches, with a secondary maximum in May — a continental fea- 

 ture — and the minimum in July and August. The South Plateau type 

 is more complex, most clearly developed in Arizona. The minima 

 occur in the fall and spring, April, May, June, rising then rapidly 

 almost suddenly to a decided maximum in July and August and a 

 secondary one in February. The cold-season rains help winter pas- 

 tures and snow protects the grass. 



The Pacific province is characterized by well-marked winter rains 

 (October or November to March or April), with wholly or nearly 

 rainless summers and large mean annual rainfall. The essential dif- 

 ference between the North (from California north) and South Pacific 

 type is found in the character of the summer dry season, the North 

 type with significant summer rains, the South practically rainless ; the 

 maximum rainfall occurring in January — a rainy season. The Mis- 

 souri, the Florida, the New Mexican, and the Pacific types exhibit 

 well-marked rainy seasons. 



The Geographical Review, August, 1917, pp. 131-44. 



An article intended for use of farmers has 



Frost also interest for silviculturists, namely, on the 



in growing season for crops in the United States, 



United following up Zon's discussion of the subject, 



States briefed in Forest Quarterly, Vol. XIII, p. 89. 



Mr. Reed, of the Department of Agriculture, 



points out that the farmer needs to know, not only the average number 



of days without frost, but the length of the growing season, depending 



on frost conditions, and the chances of his maturing a crop, this chance 



being computed in the same way as insurance risks. Three maps are 



constructed, the first showing the number of days without killing 



frosts, where the chance is 4 in 5 ; the second with a chance of i in 10, 



i. €., if losses from frost occur more frequently than once in five or 



once in ten years, success in crops is not likely. The third map shows 



