LOST KOCKS. 17 



are mostly angular, and appear to be derived from rocky 

 ledges close by. They are not " lost rocks." The summit of 

 Mt. Washington is covered by a bed of angular fragments, 

 and such fragments are common for two thousand feet below 

 the summit. Lower than this, rounded bowlders are abun- 

 dant. Professor C. H. Hitchcock, however, thinks he finds 

 real transported rocks to the very summit. The great quartz- 

 ite bowlder in the North-west Territory, Canada, is 3,250 feet 

 above sea-level. Many others in that part of the continent 

 are up to 4,400 feet in elevation ; and, in one region, attain 

 5,280 feet. Some erratics on the flanks of the Sweet Grass 

 Hills lie at an elevation of 4,660 feet. The Pierre a bot, in 

 Switzerland, is 800 feet above Lake Neufchatel, which lies 

 itself 1,427 feet above sea-level. 



We observe, in passing over the country, that the larger 

 bowlders are northward ; while toward the south, their aver- 

 age size diminishes to cobble-stones, and finally, all indications 

 of transported rocks disappear. Since we have concluded 

 that all these lost rocks have been removed from extensive 

 ledges somewhere, it seems probable that the direction of these 

 ledges is to the north. We notice also, that bowlders of any 

 particular kind become more numerous, as well as larger, as 

 we proceed northward. In fact, in some cases, by following 

 up a train of bowlders of a particular kind, we trace them to 

 their origin. That origin is often sixty or one hundred miles, 

 or even two hundred miles away. Such are the distances to 

 which the forces of Nature have moved much of these inco- 

 herent materials. 



It is not always possible to trace bowlders to their source 

 by following back a train. But we can always consider where 

 is the nearest locality of bed-rocks of the same kind as any 

 particular bowlders. For instance, in Connecticut, we can 

 find bed-rocks sometimes, in the near vicinity, but at other 

 times, not farther away than Massachusetts. In Ontario, the 

 nearest sources of the bowlders are in the regions east and 

 north of Georgian Bay. At Chautauqua, the nearest bed- 

 rock for the hard bowlders is beyond Lake Ontario and Lake 



2 " 



