294 



6'. WEI DM AN 



Wisconsin valley gradually grows shallower toward the south, 

 so that at twenty miles south of Wausau the valley bottom is 

 only about lOO feet below the peneplain, and twenty miles still 

 farther south, at Grand Rapids, the valley has no depth in the 

 pre-Cambrian, but is on a level with the more rapidly descend- 

 ing slope of the peneplain. The branch rivers of the Wisconsin, 

 such as the Big Rib, Big Eau Pleine, and Little Eau Pleine on 

 hte west, and the Pine, Trap, and Eau Claire on the east, are 



Fig. 4. — View of the dissected peneplain looking northwest one mile northwest 

 of Wausau. The even sky-line in the distance is the ancient peneplain out of which 

 the intervening valley of the Little Rib river has been sculptured. 



U-shaped for about one-quarter to one-third of their distance 

 from the Wisconsin, and then pass into narrow V-shaped valleys, 

 and finally into broad V-shaped valleys near the flat-topped 

 uplands. North of the branch rivers just named the drift is 

 very thick and the side valleys, like the Wisconsin, are either 

 wholly post-glacial or much modified by glacial action. South 

 of these branch rivers the side valleys, like the valley of the 

 Wisconsin, gradually grow shallower until their floors coincide 

 with the level of the peneplain. 



The imdissected portion of the peneplaui. — As one goes south 

 from the vicinity of Wausau, the dissection of the peneplain 



