BELT ON THE GLACIAL PERIOD IN NORTH AMERICA. 103 



and boulders of quartzite where the bed rock is quartzite. Frag- 

 ments of quartz sometmies containing gokl are easily traced to the 

 lodes (invariably to the north of them) from which they have been 

 detached, and thus many auriferous lodes have been discovered. 



The local character of the stones in the drift is opposed to the 

 supposition that to the north the land was so elevated that the ice 

 moved over the country like a great glacier, and is in favor of the 

 theory that it was formed by the retreating margin of a great accu- 

 mulation of ice. If there had been during the glacial period, high 

 mountains to the north of Nova Scotia, far travelled blocks would 

 have been of frequent occurrence. But without high ranges north- 

 wards and with it^ own hills only of moderate elevation, we find as 

 we might expect, that the blocks are easily traced to their parent 

 rock. Some boulders of granite have been carried farther, because 

 here and there granite hills rise above the general elevation of the 

 country. 



2. Transported hlocJcs of Berkshire, Massachusetts. — Sir Chas. 

 Lyell has described some long trains of large blocks that in Berkshire, 

 Massachusetts run, in nearly straight line, for distances of five, ten 

 and twenty miles, across hill and dale alike.* The direction of the 

 trains is N. W. and S. E., and they cross three chains of hills with 

 intervening valleys running N. N. E., and S. S. W. The blocks, 

 starting from the most north-westerly ridge, pass in long lines across 

 the valley to the next, and on to and in like manner through gaps 

 in the third range. 



It is argued that these blocks could not have been carried by 

 glaciers, as they would have followed the slope of the valleys and not 

 have crossed them ; and that it is more likely that they were dropped 

 by icebergs when the country was submerged, so that the tops of the 

 hills became islands and the passes straits, through which the icebergs 

 floated driven by a current from the north-west. The argument is 

 a valid one against a theory of local glaciers, but not against that of 

 continental ice. I have already shown how the advancing ice would 

 act when it encountered ranges running transversely to its flow. This 

 is an example, only I suppose the blocks were left by the retiring- 

 ice when the same process was repeated. At its greatest height the 

 ice covered the ranges and, rounded them. When durinsf its subsi- 



*Lyeirs Antiquity of Man, page 356. 



