STUDIES IN THE DRIFTLESS REGION OF WISCONSIN 185 



higher bluffs. To this is added a comparatively small percentage 



of material from the transition beds at the base of the limestone. 



Circs. — Short, direct valleys, with broad heads and narrow 



outlets, are finely shown in this vicinity. The deposits found in 



Fig. 4. Contour sketch map in which the center is occupied by the lower end of 

 a large valley — the third in the series described. At the extreme right is a bluff, the 

 highest and most massive in the group. Descending from this is the small valley or 

 circ, a, the fourth described. The positions of Sects. 4 and 5 (Fig. 2) of the 

 previous article are indicated. The bowlder deposits shown in Sec. 5 continue along 

 up the crest of the ridge b, as shown by dots. I have endeavored by the greater or 

 less concentration of the dots to indicate the relative abundance of the bowlder 

 deposits. Sec. 4 (Fig. 2) was obtained at the point c. The peculiar point d appears to 

 be largely or wholly composed of similar deposits. In the ravine, e, extensive washouts 

 reveal very thick bowlder deposits. Doubtless similar deposits occur in the other 

 ravines within the secondary hills, but the conditions are not favorable for observation. 

 The lower end of the bowlder covered spur shown in Fig. 4 is seen at/. West of 

 the middle of the valley, no hills reach the limestone horizon, save that at g. Scale 

 1000 ' to an inch. Contour lines at intervals of 50 ' . 



In this and the following maps I have indicated the base of the limestone horizon 

 by heavier contour lines. 



connection with them show several marked variations in detail 

 from those found in the larger valleys, while they have a close 

 resemblance among themselves. They all front on the Missis- 

 sippi and are the result of the comparatively rapid erosion which 

 its presence induces. The secondary hills which separate neigh- 



