BOULDERS 



215 



FIG. 



GLACIAL r.OL^LDER. la'RLINGTOX, CONNECTICUT. 



awa}' the line material, leaving piles 

 of the large fragments. The blocks 

 tend to become rounded, since the 

 edges and corners decompose more 

 rapidly than the rest of the block. Thus 

 are formed boulders of disintegration. 

 A pile of such boulders near Butte. 

 ]\Iontana, is shown in Fig. 5. Such 

 boulders remain very near the place 

 where thev were found, and, in eeneral. 



they are of the same material as the 

 underlying rock. It is evident, how- 

 ever, that in some way most of the 

 boulders of New England have been 

 transported to a greater or less distance 

 from their original home. 



The transportation of these boulders 

 is due to the series of events which 

 marked the Glacial period. Some tens 

 of thousands of years, perhaps a few 





FIG. 4. .\NOTHER ^'IEW Ol-' THE ROL'LDER SHOWN IN FIG. 3. 



