K. 1'. I.— :W. (!. F. 1". I —•.•7. 



CLi;ri\ ATKI) roilACH CHOI'S of thk noiith 



WESTERN STATES. 



DESCRIPTION OF THE REGIONS. 



The piv.>^(_'nt Itullctiii cli.sc'U.^^.scs hrn'Hy the t'oni^c rcsouici'.-^ of that 

 portion of the rnited States extend in*;- from Colorado and central 

 California north to Montana and Wa.shinyfton. The whole area ina\ 

 be divided into several well-marked regions, each of which will he 

 discussed separately. Kach region has its characteristic climate, 

 topoi;rai)hy. and ])hysi()i>-nomy. The climate depends chiefly upon 

 the latitude, altitude, and the amount and distrilmtion of the rainfall. 

 The latter factor is i>-reatly influenced hy the presence and trend of the 

 mountain chains anil the direction of the prevailinj,'' winds. In gen- 

 eral the winters are longer and moiv severe as the latitude increases. 

 The climate is cooler at higher altitudes. The Coast Range. Sierra 

 Nevada, and Cascade Mountains rob tht' winds of their moisture as 

 they blow from the Pacific Ocean eastward, thus producing an arid 

 region in the interior. The physiognomy, or general appearance, 

 depends very largely upon the character of the vegetation, which in 

 turn varies according to the climate and soil. The low and scattered 

 vegetation of the sagebrush plains of the Great Basin region, the 

 forests of the Pacific slope, and the butlalo-grass sod of the Great 

 Plains are examples of the characteristic physiognomy. It is not the 

 intention to discuss minutely the physical geograph}' of the region, 

 but these preliminarv remarks will call attention to the basis of the 

 regional classification. The relation of these pln'sical factors to the 

 agriculture of the individual regions will be referred to later. 



The soil conditions are more local in their efi'ect than the above-men- 

 tioned factors, but in some cases may profoundly modify the growth 

 of plants. The soil factors may be physical, such as its ability to hold 

 or transport water, the size of the particles, and character of the sub- 

 soil; or chemical, depending upon the chemical constituents, such as 

 the presence of excessive amounts of carbonate of soda, salt, or other 

 substances, producing alkali soils. One other factor should be men- 

 tioned, which, though not included among those determining the clas- 

 sification into areas, is nevertheless of vast importance in its relation 

 to agriculture. This is artificial water supply or irrigation. 



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