SURFACE GEOLOGY. 



41 



bowlders over the southern part of the State. It should be remembered, 

 however, that it is not claimed that all the large bowlders were trans- 

 ported by icebergs ; simply that many of them must have been so trans- 

 ported, and probably most of them were. The accompanying wood-cuts 

 will better explain my idea of the method of transport of these bowlders 

 than I can do it iu words. 



NORTH SHORE OF INLAND SEA, WITH GLACIER AND ICEBERGS. 



Paleozoic rocks and drift. 



Lauxentian hills and glacier. 



That icebergs can and do transport great quantities of bowlders, gravel, 

 and sand, is attested by thousands of observers who have seen them doing 

 it. For example : in 1822 Captain Scoresby saw a large iceberg drift- 

 ing along, loaded with earth and rocks, conjectured to be from 50,000 

 to 100,000 tons; and Captain James Kent, quoted in Kane's Arctic Expe- 

 dition, speaks of millions of tons of stone and other solid matter carried 

 by icebergs. These materials are sown broadcast over the bed of the 

 North Atlantic and the banks of Newfoundland, just as formerly over 

 the shallows bordering the southern shore of our fresh-water inland sea. 



KAMES. 



Along the summit of the watershed, between the Lake and the Ohio, 

 from the eastern to the western margin of the State, accumulations of 

 Drift material occur, which are peculiar in their character and position, 

 and of which the history is less easily made out than that of any other 

 portion of the Drift series. These are beds, banks, and hills of sand, 

 gravel, and bowlders, with little admixture of clay. In many localities, 

 these materials are heaped up into rounded, or, more often, elongated 

 hills, from 50 to 100 feet in height, to which the name " hog's-back " is 

 very frequently applied. Sometimes several of these hills are grouped 

 together, forming an undulating surface, with inclosed basins, which are 

 often occupied by lakes, or peat bogs ; though frequently without water, 

 from the porous nature of the material which surrounds and underlies 

 them. A large number of the peat bogs, lakes, and marshes, which con- 

 stitute such a marked feature in the topography of the summit of the 

 watershed, are surrounded by gravel hills, and owe their existence to the 



