70 PUBLIC PARKS OF IOWA 



possibly due to irregularities in the rock surface or to glacial drainage. 

 As erosion went on, its efforts were directed toward straightening its 

 course by the corrosion of its left bank at the Kilbourne bend. The 

 effect of this, however, was to cause still greater deflection southward 

 which was increased when the hard limestones were encountered. As 

 the loop gradually extended itself southward, the stream encountered 

 similar resisting rock walls, but of somewhat softer constitution, so that 

 corrosion took place here more rapidly than before. For a time the 

 corrosion was fairly uniform, giving the loop a regular outline. After 

 reaching the ninety-foot terrace level, however, the soft Keosauqua sand- 

 stone had been penetrated .toward the east. By the descent of the 

 strata to the southwest this sandstone remained about at the river level, 

 so that while corrosion was taking place quite rapidly in the soft sand- 

 stone toward the southwest the hard limestone eastward offered a much 

 more effectual resistance, giving rise to the northward bend below Keo- 

 sauqua, instead of a uniform curve which would result if the rocks were 

 of uniform hardness. 



Terraces. The highest terrace is about 140 feet above low water at 

 Keosauqua. From this point the terraces descend quite uniformly. The 

 most marked are the following.: 



145 feet 120 feet 90 feet 



75 feet 50 feet 25 feet 



15 feet and 10 feet 



History of the Des Moines, Vol. IV, p. 235. 



The Des Moines River. The Des Moines river flows nearly due south- 

 east, and with one exception varies little from a direct course. This 

 exception occurs in the center of the county where the river is abruptly 

 deflected from its course to the southwestward, but soon returns, forming 

 a deep U-shaped loop whose axis is a right angle to the general course 

 of the stream. The length of the loop thus formed is about five miles, 

 while across the neck the distance is not more than two miles. To make 

 this short distance the river takes a roundabout course of fully twelve 

 miles. The principal tributaries to the Des Moines are Indian, Bear, 

 Chequest and Holcomb creeks on the south, and Reed, Coates and Lick 

 creeks on the north. 



Indian Creek. This creek bisects the Des Moines between the Des 

 Moines and Fox rivers, flowing parallel with them from its source near 

 the western line of the county to Willett station where it turns eastward. 

 Except in the last four miles of its course, where it invades the Saint 

 Louis limestone, the stream flows over a thick bed of drift. In this por- 

 tion the stream has comparatively wide bottoms with more or less abrupt 

 but rounded slopes. 



Bear Creek. Bear creek has a comparatively steep declivity. It takes 

 its rise on the plateau level south of Keosauqua and, soon penetrating 

 to the rock, is bordered in the lower half of its course by more or less 

 prominent mural escarpments. It opens into the Des Momes at a high 

 angle just south of Bentonsport. 



Chequest Creek. Chequest creek rises in Davis county and flows 

 approximately parallel to the general course of the Deis Moines, into 



