HYDROLOGY. 129 



northward course to the highlands of Michigan. A section along the 

 line of the watershed across the Green Bay and Rock river valley, 

 would exhibit its peculiarities almost as conspicuously as if taken at 

 any other point, and so, to almost the same extent, would a projection 

 of the whole line exhibit the valleys, slopes and ridges that constitute 

 the salient topographical features already described. It is evident 

 then, that the present drainage systems are not the cause of these 

 features. 



At some points the elevation constituting the watershed is so slight 

 as to be scarcely perceptible. A notable example of this is found in. 

 Racine county, in the relations of the head waters of the Eau Pleine 

 river, a tributary of the Mississippi, and those of the Root river that 

 flow into Lake Michigan. Both have their rise in an extended marshy 

 valley, so nearly level that it is at times very difficult to determine 

 which way the water flows. On the county and state maps the divide 

 is placed seven miles from the point where it was at the time of my 

 visit. 



The Mississippi basin is represented in the district by the Rock 

 river system, comprising that river and its tributaries, and the Illinois 

 river system, embracing the (Illinois) Fox river and the Eau Pleine 

 river, with their branches. 



The St. Lawrence basin includes the Lake Michigan system, of 

 which the principal streams are the Root, Milwaukee, Sheboygan, 

 Manitowoc, Twin, Kewaunee and Ahnapee rivers, and the Green Bay 

 system, to which the important Fox, Wolf, Oconto, Peshtigo and Me- 

 nomonee rivers, with several minor streams, belong. 



A moment's attention to the courses of these streams reveals many 

 striking peculiarities, for most of which, upon careful study, there is 

 an obvious cause. Some of these are worthy of special attention, not 

 only from the inherent interest which they possess, but because they 

 illustrate the dependence of such important features as rivers, which 

 often determine the location and relations of great business centers, 

 upon surface geology. 



Beginning at the south, the streams of Walworth and adjacent 

 counties on the east first claim attention, and form an interesting 

 group, most conspicuous among which are White river, Sugar creek 

 and Honey creek. These streams all flow in an easterly or northeast- 

 erly direction for a distance, and then abruptly turn south, uniting 

 with each other, and at last joining the Fox river, which continues 

 south until it unites with the Illinois river, through which its waters 

 finally discharge into the Mississippi and the Gulf. All the group 

 occupy deep parallel valleys in the upper part of their course, and it 

 Wia. SUB. 9 



