GLACIAL EROSION AND TRANSPORTATION. 275 



stones, some of which, sticking fast in the glacier, were quite 

 lifted up from the bed of the cirque, while others were touch- 

 ing or resting on it ; he thinks it probable that, as iJie tem- 

 perature around the glacier constantly varies about the freez- 



Fi(j. Si.— Glacial groove on Middle Bass Island, running nearly east and west, with a 

 north-and-sonth groove crossing it. Notice the beveled edge of the east-and-west 

 groove, which is here descending to the west. 



ing-point, the incessant freezing and thawing of the water in 

 the cracks in the rock may split it, and the glacier may do the 

 work of transportation for the fragments thus broken loose. 

 On examining the interior of an empty cirque, we observe 

 that a bursting, not a scooping out. of the rocks has taken 

 place." 



The writings of Penck, Lowl, and other European geolo- 



