38 PHYSICAL GEOGKAPHY. 



fall was not determined, but it could not differ much from the pre- 

 ceding space. 



Chart No. 2. On this chart we have the mean annual rainfall 

 between 1869 and 1879. Along the Missouri, as far west as to the 

 line which starts near the mouth of the Big Sioux River, and 

 crosses the State southerly and then southwesterly, and then a 

 little east of south until it strikes the south line of the State where 

 the Blue River emerges from it, over this space the mean annual 

 rainfall during this period was thirty-eight inches. Closer to the 

 river the rainfall was still greater. Between this last line and the 

 next which starts on the Missouri a little south of the mouth of 

 the Bow River, runs diagonally in a curve until near Kearney, and 

 then south to the south line of the State, this section thus bounded 

 receives an average annual rainfall of thirty-two inches. West of 

 this last line there is another, which starts at the mouth of the Ni- 

 obrara, curves southwesterly to a point a little east of North Platte, 

 and then slightly southwest to a point a little west of Culbertson, 

 on the Republican River. An average annual rainfall of twenty- 

 six inches covers the space bounded by these lines. The next line 

 west commences on the north line of the State at the mouth of the 

 Keya Paha, runs southwest across the State, striking the south line 

 half way between Culbertson and the west line of the State. The 

 space between this line and the last receives an average annual 

 rainfall of nineteen inches. Between this line and the next west, 

 which starts a little east of the 101 meridian, runs in a curve south- 

 westerly to a point near Lodge Pole, on the Union Pacific Railroad, 

 and then south to the south line of the State. The space bounded by 

 this and the last line receives an average annual rainfall of seventeen 

 inches. West of this line the rainfall is not definitely determined, 

 but it probably does not differ materially from the preceding sec- 

 tion. It should be remembered in examining these charts, that 

 towards each line the amount of rainfall shades into the next di- 

 vision. 



EXCEPTIONAL METEOROLOGICAL CONDITIONS IN THE NIOBRARA 



REGION. 



In Chapter I., some exceptional physical features were noted in 

 the Niobrara region. These exceptional physical features no doubt 

 help to produce the exceptional meteorological conditions. Of late 

 years more than formerly, in these sections during June, July and 



