264 Dr. Hitchcock on some Phenomena of Drift. 
In the third place, it is almost equally difficult to explain the 
dispersion of these blocks by floating icebergs. If the number of 
blocks had been only one or two, or even not more than fifty, it 
_ might be possible that a large iceberg should have dropped them. 
But what iceberg could have loaded itself with enough of these 
blocks to have strewed them so thickly for so many miles? And 
who will believe that successive icebergs, striking against the 
same ridge in Canaan, should have torn off and borne away suc- 
cessive blocks in precisely the same direction, so as to have 
lengthened out the train? Besides, although an iceberg would 
have the power to break off the blocks, where is the agency by 
which they would be raised upon its back ? 
Finally, I know of but one or two facts in geology that can 
furnish us with the slightest clue to the manner in which these 
trains of blocks were produced. One is, the transportation of 
blocks of stone in what is called packed ice, upon rivers in high 
latitudes. These sometimes form lines of bowlders along the 
shore for a considerable distance ; as in the river St. Lawrence, 
described by Mr. Lyell in Vol. I of his Principles of Geology, (p. 
371.) If, therefore, we could suppose a large river passing from 
the mountain in Canaan across the hills southeasterly, and the 
climate much colder, it might afford a possible though very im- 
probable explanation of the case. But one has only to look at 
the region to see, that in its present configuration, this is out of 
the question, unless a river can flow without a bed, and over 
ridges 600 or 800 feet high. And as to any essential change of 
configuration there since the drift period, I think I have proved it 
absurd in my Final Report. 
The second case to which I referred is that of the medial mo- 
raines of glaciers; that is, trains of blocks borne along on the 
back of the middle of the glacier, in consequence of the union of 
two glaciers, whereby the lateral moraines of the separate glaciers 
are forced to the surface after the coalescence. One has only to 
look at such moraines, as represented by Agassiz in his Etudes 
sur les Glaciers, to see that they a good deal resemble the trains 
of blocks in Richmond; and then, such a mode of transport 
would show why they are not rounded. But when we come to 
examine the country with reference to a glacier, we shall find it 
about as difficult to imagine the existence of one there as of a 
