112 



GEOLOGY OF THE SECOND DISTRICT. 



We have, both here and elsewhere, tiiree phenomena related in kind to each other ; but 

 ■whether lliry are related as to cause, cannot at this stage of our inquiries be determined. I 

 refer to the scorings or scratches upon rocks, the distribution of boulders, and the wearing of 

 rocks in the mode represented by the cut at the head of this section. As some of my readers 

 mav be uiiaccjuainted with the appearance of a rock which is scratched or scored, I have in- 

 troduced a cut which exhibits, as well as possible, these peculiar markings. I have borrowed 

 it from my colleague Mr. Vanuxem, who procured it for the purpose of showing the tremulous 

 mniion of boulders when passing over the surface, which is indicated by the regular inter- 

 rupted lines. 



116. 



In all the effects specified above, water is concerned, but in each case the circumstances 

 arc modified. In the first, water bears along rocks and stones, gravel and sand, frozen into 

 cakes of ice ; in the second, boulders are frozen probably in large masses of ice, termed ice- 

 floes or icebergs, which, floating out to sea, melt gradually away, and drop them as it may 

 happen, or as they are thawed out. Now these icebergs float in directions quite constant, and 

 hence may ground regularly upon the sounding of certain shores, where the greater part of 

 llieir burden of rocks is dropped. By this hypothesis, I would explain the collection of 

 boiddcrs in certain zones or belts. The third or last phenomenon has nothing to do with ice : 



