208 Wisconsin Academy of Sciences, Arts, and Letters. 



very curiously, into peaks and ridges, in various attitudes on the 

 summit and sides of the moraine. 



Relations to Drift Movements. — This is manifestly of most vital 

 consideration. The course of drift movement may be determined, 

 (1) by the grooving of the rock surface, (2) by the direction in 

 ■which the material has been transported, (3) by the abrasion which 

 rock prominences have suffered, (4) by the trend of elongated 

 domes of polished rock, and, (5) less decisively, by the arrange- 

 ment of the deposited material and the resulting topography. 

 Eecourse has been had to all these means of determination, in 

 that portion of the range that has been carefully investigated, and 

 their individual testimony is entirely harmonious, and their com- 

 bined force is overwhelming. Exceptional opportunity for positive 

 determination is afforded by the protruding knobs of Archasan 

 rocks before alluded to, from which trains of erratics stretch away 

 in definite lines, continuous with the striation on the parent knobs, 

 and parallel to that of the region, as well as concordant with the 

 general system. The united import of all observations, in eastern 

 Wisconsin, testifies to the following remarkable movements, which 

 may be taken as typical, and which are here given, because they 

 have been determined with much care. Between Lake Michigan 

 and the adjacent Kettle range, the direction was obliquely up the 

 slope, as now situated, southwestward, towards the range. On 

 the opposite side, between the Green Bay valley and the range, the 

 course was, after surmounting the cliff bordering the valley, ob- 

 liquely down the slope, southeastward, toward the range. In the 

 Gr^en Bay trough, the ice stream moved up the valley to its 

 watershed, and then descended divergingly the Rock river valley. 

 Between the Green Bay valley and the Kettle belt on the west, 

 the course was up the slope, westward, or southwestward, accord- 

 ing to position. These movements, which are imperfectly shown 

 on the diagram, exhibit a remarkable divergence from the main 

 channel toward the margin of the striated area, marked by the 

 Kettle range. 



Much of the data relating to the movements, outside of Wis- 

 consin, has been derived from a study of publications relating to 

 the geology of the several states, to whose authors I am indebted, 



