THE GLACIAL DRIFT. 611 



In the central plain of Adams and Juneau counties, though the 

 ramifying ridge-and- valley topography is wanting, no less indisputa- 

 ble topographical proof is at hand of the immunity of the region from 

 the glacial action in past time; for, dotting the surface of the plain, 

 we find the numerous sandstone towers that have been so often alluded 

 to in. this report. The fragile character of these peaks is sufficient 

 evidence that they could never have stood in the path of a glacier. 



The altitude of the driftless area, as compared with the drift- 

 bearing regions, becomes a matter of some importance in any attempt 

 to explain the absence of the drift phenomena. It has been stated 

 by some writers that the driftless area is higher than the drift-bearing, 

 and was, consequently, not subjected to glacial invasion. It is true 

 that in general the eastern half of the state ie> lower than the western, 

 but from what follows it will be seen that farther than this the state- 

 ment is inaccurate. From the south line of the state as far north as 

 the head of Sugar river, in Cross Plains, the country west of the drift 

 limit rises rapidly 200-400 feet. Just north of the head of Sugar 

 river, the limit crosses high ground the western extension of the 

 high limestone and prairie belt of northern Dane and southern Colum- 

 bia counties and the altitudes east of the limit are as great as those 

 to the west; whilst in passing from the head of the Catfish river west- 

 ward, a glacier must have made an abrupt ascent of fully 300 feet. 

 North of Black Earth river, the limit has the higher ground, by 200 

 feet, on the east. Sank prairie is crossed on a level, and though 

 higher ground occurs west of the prairie, its topography and the ab- 

 sence of drift show that the glacier never reached so far. "Where the 

 quartzite range north of Sank Prairie is crossed by the limit, it is 

 higher (850 feet above Lake Michigan) than any part of the driftless 

 area except the Blue Mounds, whilst a few miles east a great develop- 

 ment of bowlders and gravel is found on one of the highest portions 

 of the range (900 to 950 feet altitude). From the Baraboo north to 

 the Sauk county line, there appears to be no relation between the 

 position of the limit and the altitude of the country. From the north 

 line of Sauk county, in curving, as previously described, to the east- 

 ward and northward around Adams county, the limit is on the very 

 crest of the divide. From its position near the middle of the east 

 line of Adams county, the country, for 40 miles to the west, is from 

 100 to 200 feet lower. From the northwest part of Adams county 

 to the "Wisconsin river the limit is in a level coantry ; whilst from the 

 Wisconsin westward the country north of it is everywhere much 

 higher than that to the south, the rise northward continuing to within 

 thirty miles of Lake Superior. 



