A PARTICULAR CASE OF GLACIAL EROSION 357 



fronts, which are also relatively more disrupted than are the rears. 

 As an example I may mention an occurrence in St. Paul, already 

 briefly described. 1 At that place a mass of shales, representing 

 recognized beds of the Galena (Trenton) series, covers about an 

 acre of surface. As shown in the grading of the streets which cross 

 it, the shale is surrounded by northern drift, which lies over part 

 of it, and probably under all of it. Other cases of similar import 

 were cited in the article referred to. 



The manner in which the glacier transported these large masses, 

 without overturning them, was a matter of wonder until the discovery 

 of the case here described. This particular occurrence shows at 

 least how the great clay-shale masses may have been plowed up. 



T Journal of Geology, Vol. VI, p. 688. 



