CLIMATIC CHANGES IN THE PRAIRIE REGION. 305 



Prof. Hayden,* in his geological survey of Nebraska, "examined young 

 cottonvvoods ten years old from the seed, measuring fifty feet in height, and four 

 feet in circumference ; others of the same age, two feet, eleven inches in circum- 

 ference, and thirty feet high; at eight years old, two feet, eight inches in circum- 

 ference ; at four years old, eighteen inches in circumference and twenty feet 

 high; and at seven years old, two feet, one inch in circumference, and fifteen 

 feet high. Soft maple of ten years growth, two feet, eight inches in circumfer- 

 ence, and thirty feet heigh; at seven years old, two feet, one inch in circumfer- 

 ence, and fifteen feet high. Common locust of ten years growth, two feet, five 

 inches in circumference, and fifteen to twenty feet high ; five years from seed, 

 twenty-three inches in circumference Black walnut, ten years from seed, 

 thirteen inches in circumference and fifteen feet high. Box elder ten years old, 

 two feet, two inches in circumference. Equally good results have been obtained 

 in Kansas, and in the valley of Salt Lake where irrigation is practised. * * " 



The writer recalls to memory one grove beyond the ninety-eighth meridian 

 which during the last ten years has been cut down and grew up, at least three 

 times, and the material hauled off for fire-wood, the trees at each cutting having 

 attained a heighth of from five to twelve feet. If this belt had been permitted 

 to remain unmolested, it would have been by this time a dense woods. 



It seems to be possible, that under the proper conditions of culture, these 

 young forests may be extended to the foot of the mountains, as the single trees, 

 hedges and groves first planted by the settler, in connection with his extensive 

 disturbance of the soil, bring about such changes, that as the conquest of the 

 prairie is advanced, the forest belt is pushed out with it. The first tentative at- 

 tempts at hedges and little door-yard clumps, acquire the power of retaining, not 

 only the local humidity, but of attracting and precipitating that which the winds 

 bear, which, without the presence of the trees, would have passed over the region 

 as dry winds. Deluging storms occur less frequently, and the rain does not run 

 off the cultivated surface, as rapidly as when the comparatively hard and baked 

 earth alone was presented to the shower. Evaporation from the earth directly, 

 as well as through the medium of the vegetation, takes place throughout the sea- 

 sons, and where once, too, the sun shone through an atmosphere apparently 

 devoid of sufficient humidity even for the condensation of dew. 



Horace Greely wrote in the Tribune, on one occasion after a trip on the 

 " Great American Plains : " "I have a firm faith that all the great deserts of 

 the Temperate and Torrid zones will yet be reclaimed by irrigation and tree 

 planting." 



It will be conceded that the possibilities of forest growth on the Great Plains, 

 as has been hurriedly shown, are not inconsistent with the view presented in this 

 paper on the "Origin of Prairies;" that they are due to insufficient precipitated 

 moisture, which is undoubtedly the cause of their treelessness, not, however, for 

 the reason that the absolute precipitation is not enough to sustain tree growth 

 when once inaugurated and guarded by conditions, for on at least a larger portion 



*Report of the Secretary of the Interior, 1868. 



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