PRE-GLACIAL MOINGONA RIVER. 



CHARLES KEYES. 



As Iowa's master waterway, tlie Des Moines river rises be- 

 yond the extreme northwest corner of our State, and flows en- 

 tirely across it to the southeast comer. The name is the oldest 

 term applied by Europeans to any feature of the territory. As 

 such the title is derived from the Moingona Indians whom Jolliet 

 and Marquette, commonly ascribed discoverers of the Mississippi, 

 found in the summer of 1673 located near the river's mouth. 



PhysiogTaphically the present Des Moines river is made up of 

 two very distinct parts. The valley in which it flows, between 

 the city of Des Moines and Keokuk, is very much older than 

 that portion above the Capital City. The lower stretch is a 

 broad, flat-bottomed, rock-cut gorge ; the upper reach is a deep^ 

 V-shaped trench mainly sunk in imconsolidated till deposits. 

 Both parts are post-glacial valleys ; the one antedating the Wis- 

 consin ice invasion and the other being subsequent to it. Unlike 

 the upper stretch the lower reach is now engaged mainly in 

 clearing out an old till-fiUed trough. It is, however, to some 

 evidences of the former existence of an ancient stream, a pre- 

 Glacial Des Moines river, or the Old Moingona river, that at- 

 tention is here directed. 



Possibility of the existence of a pre-Glacial precursor of Iowa's 

 chief waterway has been with me a theme of long standing. The 

 actual location of such a stream first took form more than 30 

 years ago, when I discovered that there was northeast of Capitol 

 Hill in the city of Des Moines, a deep, drift-filled gorge which 

 cut out the principal coal seams. Although during the period 

 mentioned the subject was not always pursued with uniform 

 vigor because of the fact that sufficient data had not yet ac- 

 cumulated special interest in it was again recently revived by 

 the disclosure in quick succession of numerous facts bearing 

 directly upon the solution of the problem. 



When the matter was first broached so long ago as 1882 two 

 circumstances were particularly significant. One was the aban- 

 doned drift-filled gorge already mentioned; and the other was 

 a certain "Quaternary Section Eight Miles Southeast of Des 

 Moines"^ in which tills and gi'avels were found in such posi- 

 tion as to indicate their situation in a valley much older, larger 



'Proc. Iowa Acad. Sci., Vol. I, pt. ii, p. 30, 1892. 



