70 MAN AND THE GLACIAL PERIOD. 



White Mountains one's attention can scarcely fail of be- 

 ing directed to the difference between the material of 

 which the mountains are composed and that of the nu- 

 merous boulders which lie scattered over the surface. 

 The local geologist readily recognises these boulders as 

 pilgrims that have wandered far from their homes to the 

 northward. 



Trains of boulders, such as those already described in 

 Ehode Island, can frequently be traced to some prominent 

 outcrop of the rock in a hill or mountain-peak from which 

 they have been derived. One of the earliest of these to 

 attract attention occurs in the towns of Eichmond, Lenox, 

 and Stockbridge, in the western part of Massachusetts. 

 Here a belt of peculiar boulders about four hundred feet 

 wide is found to originate in the town of Lebanon, N. Y., 

 and to run continuously to the southeast for a distance of 

 nine miles. West of Fry's Hill, where the outcrop occurs, 

 no boulders of this variety of rock are to be found, while 

 to the southeast the boulders gradually diminish in size as 

 their distance from the outcrop increases. Near the out- 

 crop boulders of thirty feet in diameter occur, while nine 

 miles away two feet is the largest diameter observed. 



Sir Charles Lyell endeavoured to explain this train of 

 boulders by the action of icebergs during a period of sub- 

 mergence — supposing that, as icebergs floated past or 

 away from this hill in Lebanon, N". Y., they were the 

 means of the regular distribution described. It is need- 

 less to repeat the difficulties arising in connection with 

 such a theory, since now both by observation and experi- 

 ment we have become more familiar with the movement of 

 glacial ice. What we have already said about the trans- 

 portation of boulders over Switzerland by the Alpine 

 glaciers, and what is open to observation at the present 

 time upon the large glaciers of Alaska, closely agree with 

 the facts concerning this Eichmond train of boulders, and 

 we have no occasion to look further for a cause. 



