hy the expansive power of freezing Water. 141 



the outward expansion on its borders. When an egg is 

 frozen, it bursts from the same cause, with a wide fissure. 

 The same is true of trees, which in very|severe^ weather 

 sometimes burst with a loud report. Again, I have ob- 

 served, that in large ponds and lakes where thick ice has 

 been formed, a disruption, just at the edge, between the 

 main body of the ice and the shore, has taken place, and 

 that the ice has projected upon the shore a considerable 

 distance over the line of disruption. In case this ice had 

 formed upon a rock near the shore, the rock must have 

 been carried with it in its expansion towards the shore, 

 and must have been left in that situation at the melting of 

 the ice. When the ice formed again, it would be carried 

 further forward, and since in New-England the ice forms 

 and melts often several times in succession during a single 

 winter, it is easy to see, that in several years a rock might 

 make very perceptible progress.* I have also noticed, 

 that, in New-England, fences which originally stood erect, 



disruption," and by your remarks oh the phenomenon in No, III. of your 

 Journal. In this instance, " the earth, to the depth it had frozen the past 

 ■winter, 14 inche?, was broken in a straight line above 6 rods, and the south 

 edge of the fissure, having been forced up, overlapped the other, three 

 feet." 



* Your correspondent Pe/)-es thinks it impossible, that these rocks can 

 be moved by ice, and asks with an air of triumph, how it can remove some 

 rocks, and not others. I answer, that the expansion of the ice will move 

 all the rocks which are within its reach, except those which are so firmly 

 fixed in the ground, that the resistance arising from this cause, is greater 

 than the force by which the ice attaches itself to the rocks. Where such 

 is the case, there will be a disruption between the rock towards the middle, 

 and the ice will, if the inclination be not too great, be driven upon or over 

 the rock. This eflect I have often seen produced. 



It may be objected, that if this account of moving rocks were true, such 

 phenomena would be more frequently seen. In answer to this I observe, 

 that most of the rocks capable of being the subjects of such phenomena, 

 have probably been deposited on the shore ages ago ; and i cannot but re- 

 gard the immense piles of loose rocks with which the borders of most ponds 

 and lakes iu New-England are lined, as the effects of this cause. At least, 

 those who reject this explanation, ought to point out some other way, by 

 which these piles of rocks were accumulated. But it may be replied, if 

 you have assigned the true cause, why have not all rocks situated within 

 reach of the ice in lakes, been long since carried to the shore ? To this it 

 may be said, it is not without example, that new lakes should be formed, 

 or old ones enlarged or diminished by earthquakes, by masses of materials 

 deposited by torrents, by land-slips, or other causes with which we are less 

 acquainted. Any one of these circumstances, would be sufficient to pro- 

 duce such an effect. Besides, though there are but few instances, on 

 record, of moving rocks, such phenomena may have frequently occurred 

 without being observed, or if observed, without being recorded. 



