RIVER SYSTEMS AND GENERAL SURFACE SLOPES. 415 



Fox drains about 49 townships, including the easternmost part of Mar- 

 athon and Portage, almost all of Waushara, all of Marquette, south- 

 eastern Adams, about four townships in northern Columbia, and all 

 of Green Lake within the district; and the Rock drains about 31 

 townships, including eastern and southwestern Columbia, and nearly 

 all of Dane. 



Much the most important of these streams is the Wisconsin, which 

 constitutes, with its valley, the main topographical feature of the 

 region. The total length of this river, from its source to its mouth, 

 is about 500 miles. Rising in Lac Vieux Desert, on the summit of 

 the Archaean watershed, at an elevation of 951 feet above Lake Michi- 

 gan, it pursues a general southerly course for 300 miles over the crys- 

 talline rocks, and then, passing on to the sandstones which form its 

 bed for the remainder of its course, continues to the southward for 

 some eighty miles more. Turning then westward, it reaches the 

 Mississippi within 40 miles of the south line of the state, at an eleva- 

 tion of only 30 feet above Lake Michigan. Like all the other streams 

 which run to the south, southeast, and southwest from the crystalline 

 rocks, it has its quite distinct upper or crystalline rock portion, and 

 its lower or sandstone portion. In the case of the Wisconsin, how- 

 ever, we may conveniently regard the river as having three distinct 

 sections: the first including all that part from the source to the last 

 appearance of crystalline rocks in the bed of the stream, in the south- 

 ern part of Wood county; the second, that part from this point to the 

 Dalles, on the south line of Adams and Juneau counties; and the 

 third, that portion from the Dalles to the mouth of the stream. The 

 first of these divisions is broken constantly by rapids and falls, caused 

 by the descent south of the surface of the Archaean area, and by the 

 obstructions produced by the inclined ledges of rock which cross the 

 stream. The second and third sections are alike in being almost en- 

 tirely without rapids or falls, and in the nature of the bed rock, but 

 are separated by the contracted gorge known as the Dalles, which, 

 acting in some sort as a dam, prevents any considerable rise in the 

 river below, the water above not unfrequently rising as much as 50 

 feet in flood seasons, whilst below the extreme fluctuation does not 

 exceed 10 feet. The total lengths of the Archaean, upper sandstone, 

 and lower sandstone sections of the Wisconsin, are, respectively, 300, 

 62 and 130 miles, the distance through the Dalles being about seven 

 miles. 



For a description of the course of the river more in detail, we may 

 begin with its entrance into the district in the northern part of Mara- 

 thon county. From here, where the width according to the land 



