NATURAL AREAS AND REGfOVq 



493 



northwest corner of the main portion 

 and all of the Panhandle. The surface 

 is a sloping plain which descends from 

 an elevation of over 4500 ft. in the north- 

 west corner, and has its surface cut here 

 and there by the streams into narrow 

 V-shaped canyons lying between the 

 broad, flatr-topped hills. While the soil 

 is sufficiently fertile for excellent farm- 

 ing, the scant rainfall, which averages 

 only 15 in. per year and is often much 

 less, greatly restricts agricultural opera- 

 tions; hence the greater part of the 

 region is in pasture and is but thinly 

 settled. The north side of the Cimarron 

 River in the Panhandle is bounded by 

 the Black Mesa, a bed of volcanic lava, 

 now standing high above the level of 

 surrounding elevations and giving to the 

 landscape a characteristic appearance 

 not found elsewhere in the state. 



II. CLIMATE 



While in general the climate of Okla- 

 homa is regarded as temperate it is 

 characterized by many extremes of 

 weather both of hot and cold, wet and 

 dry. The usual seasonal changes in 

 temperature, like those on the Great 

 Plains in general, are great, ranging 

 from at least 25° below zero to 116°, 

 or even more, above. Killing frosts 

 may be expected in the northwestern 

 part of the state in the first half of 

 October, while they may be a month 

 later in the southeastern portion. The 

 latest frost in the spring may occur in 

 February in the southern part, or as 

 late as the last of April in the higher 

 western and northern portions; one 

 degree of difference in temperature, 

 where conditions otherwise are the same, 

 may be noted for each 65 ft. of difference 

 in elevation. However, the heat of 

 summer is very greatly modified, espe- 

 cially in the southern half of the state, 

 by the influence of the Gulf of Mexico, 

 and the nights are usually comfortably 

 cool even in the hottest summer months. 

 The average annual precipitation varies 

 from 15 in. or less in the Panhandle and 

 the High Plains Region generally to 

 45 in., or occasionally more, in the 



southeastorn corner of the state. The 

 niiiiy soiuson inciiides the montha of 

 April to Scptonibcr, thoURh July and 

 August arc frofpientiy very dry, and 

 occasionally the fall and winter months 

 arc marked liy coii.sidoruble preci|)ita- 

 tion. Snow-falls of u foot or more on 

 the level sometimes are experienced in 

 the northern sections, while the soiith- 

 ern half of the state frequently piuy^ea 

 th' entire year without the fall of a 

 single snow-flake. 



The percentage of actual hours of 

 sunshine out of the number po-^ible 

 averages about 50 in winter and nl)out 

 65 in summer, while in July, .\ugust and 

 September, it is usually .SO to 85 per cent 

 of the po.ssible hours. The prevailing 

 winds are from the south. The tables of 

 the United States Weather Bureau 

 Station at Oklahoma City show, for a 

 period of ten years, "a total of 132 

 months, that south winds prevailed for 

 94 months, southeast for 10 months, 

 north for 25 months, northwest 2 months, 

 and northeast 1 month." 



A never-to-be-forgotten characteristic 

 of the climate in Oklahoma is the great 

 and sudden drop in temperature which 

 occurs upon the approach of a so-called 

 "norther'' in the late fall and winter 

 months. After a period of warm 

 weather when the thermometer registers 

 80° or more, say in November, with a 

 light warm south wind, a leaden haze 

 may usually be seen rising gradually 

 above the northern horizon. After 

 several hours the wind changes direction 

 almost instantaneously and comes from 

 the north with a velocity sometimes 

 reaching GO mi. or more per hour, bring- 

 ing with it a drop in temperature of 

 50° to 00° within a very few hours. In 

 fact, the present writer has seen the 

 mercury drop 00° in ninety minutes on 

 such occasions, after which a further 

 drop of several degrees may occur but 

 more slowly. Woe unto num or bojust 

 caught out unprepared for the "north- 

 er!" There is usually little or no 

 snow-fall in connection with these 

 storms, though when such d<x?a occur 

 it is apt to be esiwcially severe, and the 



