Sixteenth Annual Meeting. 135 



glacial period, as it is called, the same as at present? We judge of the past by the pres- 

 ent. During our present annual winters, when the earth is frozen, the land covered 

 with snow, and the rivers low and dry, erosion is reduced to a minimum. During the 

 glacial period, evidence is not wanting of the presence of vast fields of ice as far south 

 as 39° in the eastern part of the State, perhaps not during the last glacial period, but at 

 ether former times. North of lat..'>!>°, then, as in the headwaters of the Kaw, it is reasonable 

 to presume that erosion would be less rapid; while farther south — as in the valleys of 

 the Neosho and Arkansas, in consequence of the melting of much snow — erosion must 

 have been greater. Following each glacial period in the great Platonic springtime, dur- 

 ing the disappearance of the ice, and the greatly increased annual rainfall of those 

 periods, even up to a few thousand years ago, erosion should be somewhat greater. Yet 

 on the other hand, considerable soil and some bowlders have been deposited in north- 

 eastern Kansas by the action of the Missouri and by ice from the regions of the north, 

 perhaps enough to neutralize the increased erosion. These considerations only modify 

 the length of time of our calculation, and do not nullify it. 



II. — The Agency of Air. 



Air, like water, acts in a two-fold capacity: First, by taking up, on decomposition, 

 the elementary constituents of the rocks; and second, by taking up and holding in sus- 

 pense, and carrying bodily, particles of earth, sand, etc. It acts as an auxiliary to water 

 by leveling the hills and rilling the rivers; but it also carries earth entirely and forever 

 out of the State. 



It is known that, though the prevailing winds be north and south, the general tend- 

 ency is from the west and toward the east. A particle of sand, though it may be blown 

 north and south across the State a thousand times, will ultimately find its way out of 

 the State toward the east ; but by that time it has become worn so fine and has apparently 

 so little grit as to be scarcely recognizable as a former resident of Kansas. Did it come 

 from Colorado? Perhaps; but certainly not from beyond the Rockies. 



As to the amount of soil that is removed, there are no statistics that are at all trust- 

 worthy. Let it suffice to say that exposed situations lose the most, and sheltered situa- 

 tions receive the most. Kansas is an exposed State, therefore it loses more soil than it 

 receives, especially in the west. If it be admitted for the sake of argument, that even 

 the one-thousandth part of an inch be removed in the course of one of our three-day 

 dust storms, and that there are four such storms in a year, it will be seen that one inch 

 would be removed in 250 years, which is twice as fast as the rate of erosion by water. 



ILLUSTRATION. 



During the spring of 1880 a notable dry dust storm, with a southwest wind, took 

 place, that raised vast clouds of coarse sand, fine sand, and dust, the last two to great 

 heights, and to such an extent as to partially obscure the sun all over the State of Kan- 

 sas. At its close, a deposit of tine dust was observed to have taken place in Kansas City, 

 St. Joseph, and even as far east as St. Louis. In conversation subsequently with our la- 

 mented Prof. Thomas, I learned from him that he caught some of the fine dust that fell 

 in Topeka the night after the storm ended, examined it in the microscope, and found it 

 to consist almost entirely of finely-comminuted silica; but where it came from he had 

 no idea. I, on the other hand, at that time in Barton county, observed that on level 

 prairies, all unprotected loose soil, mainly sand and light loam, even down to the grass 

 roots, was taken up high in air and carried off"; but where it went to I had no idea. 

 Certainly an equal amount was not deposited from the opposite direction. Similar 

 storms are quite frequent in western Kansas. 



DEDXCTION. 



The air, then, is an important factor in the removal of soil; though the rate of re- 

 moval may not be computed. 



