cxiix 



"on the origin of ravines in the prairie. 



In this paper I propose to record my observations upon this subject, as 

 I do not remember to have seen it mentioned in any of your transactions. 



To the present generation it may be of little interest, as they know — or, 

 if curious, can be informed by those who have witnessed the change — how 

 most of the ravines in the prairie originated ; but a century hence, should 

 the question be asked, it would probably prove to be a problem not so 

 easily or satisfactorily solved, unless there should be accessible some well 

 authenticated record of their origin. I therefore call your attention to this 

 subject. 



The prairie situated one mile east of Hillsboro could, thirty years ago, 

 during the wet season, truly be said to be an immense lake, interspersed 

 with islands ; for the tough sod, together with the rank growth of grass, 

 reeds, and flags, offered a considerable barrier to the rapid flow of the wa- 

 ter during the spring and summer floods, as it had to filter through the 

 roots of the grass, or percolate the drifts of broken and decaying vegeta- 

 tion which always lined the shores of the prairie-lakes, to again encounter 

 the rough surface of the tough native sod in its struggle to reach the fluid's 

 goal. Its progress was necessarily so slow that it did not attain suflScient 

 velocity to cause any washing of the soil ; however, it forced the water to 

 spread over a large scope of country, requiring at that early day weeks to 

 discharge the same volume that will now pass off in forty-eight hours. 



The change was wrought in this way : after the first of June, until quite 

 late in the fall, ihe prairies used to swarm with " green-head" flies, and so 

 vigorous in their attacks were they that all domestic animals were driven 

 to the woods after eight o'clock in the morning, nor did they dare to return 

 until just before sunset, when they would emerge from their retreats and 

 march in single file through the long grass to the nearest pond for water, 

 and thence on to their feeding- ground — the different neighbors' cattle 

 having their own path, pond, and feeding-ground. In course of time, this 

 constant passing to and from the pond completely killed the sod, and when 

 the spring rains came, the cow-path being lower, and the water meeting 

 with no obstruction, poured down these new-found channels, and in time 

 cut a ravine, which in most instances has become of sufliicient size and im- 

 portance, where it crosses a public road, to require bridging. 



In conclusion, I would say I have watched quite a number of these coiv- 

 path streams from their inception to the present day ; and the size they 

 have attained during this time would astonish any one after becoming 

 acquainted with their history. 



The Corresponding Secretary laid a number of exchanges on 

 the table, and oalled special attention to the following : 



Bulletin of the Anthropological Society of France, No. 5, July, 1873, p. 

 671, M. de Mortillet presented a flint lance-head, found by the Abbe Bour- 

 geois in the Miocene, of unquestionable human authorship, and this dis- 

 covery put the question of the existence of men in the Miocene capable of 



