456 GEOLOGICAL SURVEY OF THE TEEEITOEIES. 



These remarks were sent to the distinguished meteorologist, Professor 

 Henry, rather to draw the attention of his cultivated mind to the phe- 

 nomena than to assert a theory. Tet there are facts which sustain the 

 popular notion of a climatic change, manifested in a more humid at- 

 mosphere, in greater rain-fall and a change of vegetation. A gentleman 

 who has given much attention to meteorology writes me that he is not 

 satisfied that settlements have sufficiently changed the surface of the 

 country west of the Missouri to affect the climate. " The increased 

 rains," he says, " I apprehend, are due to extra mundane or cosmic in- 

 fluences not yet understood." 



It is certain that rains have increased ; this increase has coincided 

 with the extension of settlements, railroads, and telegraphs. If influ- 

 enced by these, the change of climate will go on ; if by extra mundane 

 influences the change may be permanent, progressive, or retrograde. I 

 think there are good grounds to believe it will be progressive. Within 

 the last fifteen years, in Western Missouri and Iowa, and in Eastern 

 Kansas and Nebraska, a very large aggregate of surface has been broken 

 up and holds more of the rains than formerly. During the same period 

 modifying influences have been put in motion in Montana, Utah, and 

 Colorado. Very small areas of timbered land west of the Missouri 

 have been cleared ; not equal, perhaps, to the area of forest, orchard, 

 and vineyards planted. Hence it may be said that all the acts of man 

 in this vast region have tended to produce conditions on the earth's sur- 

 face ameliorative of the climate. With extended settlements on the 

 Arkansas, Canadian, and Red Biver of the South, as well as on the 

 Arkansas, on the river system of the Kaw Valley, and on the Platte, 

 the ameliorating conditions will be extended in like degree ; and it par- 

 takes more of sober reason than wild fancy to suppose that a perma- 

 nent and beneficial change of climate may be experienced. The appal- 

 ling deterioration of large portions of the earth's surface, through the 

 acts of man in destroying the forests, justifies the trust that the culture 

 of taller herbage and trees in a region heretofore covered mainly by 

 short grasses may have a converse effect. Indeed, in Central Kansas, 

 nature seems to almost precede settlements by the taller grasses and 

 herbage. 



TEEE GBOWTH ON THE PLAINS. 



The principal native trees on the Plains west of ninety-seventh merid- 

 ian are : 



Cottonwood, fPopulus Canadensis and P. Monolifra.J 



Walnut, fJuglans Nigra.) 



Elm, (TJlmus Americana.) 



Ash, (Fraxinus Americana.) 



Box Elder, (Acer Negundo.) 



Hackberry, (Celtis occidentals.) 



Plum, (Prunus Ghickasa.) 



Bed Cedar, fJuniperus Virginiana.) 



To these may be added Willow fSalix) and Grape Vines ( Vites 

 ceestivalis ; ) and also the Locust (Robinia pseudo-acacia) and Wild 

 Cherry (Cerasus Virginiana) mentioned by Abert as occurring on the 

 Purgatory. 



The black walnut extends to the one hundredth meridian ; how much 

 farther I am unable to say. The elm and ash are of similar, perhaps 

 greater range. Hackberry has been observed west of one hundred and 



