3o 4 POPULAR SCIENCE MONTHLY 



in this way were the awful denunciations of an offended God, by the sure ex- 

 termination of every beast of the field and every creeping thing that crawled 

 upon the face of the earth. 



To these causes he believed to be due, not merely the deposits of the 

 coastal plain, but, as well, the barrenness of Labrador and the north- 

 eastern portion of the continent, and the general phenomena of the 

 glacial drift, the boulders of the latter being conceived as transported 

 by floating ice. 



These essays, it may be noted, were favorably reviewed by Silliman 

 in the third volume of his Journal, even the idea of the fusion of the 

 polar ice-cap being allowed to pass with no more serious criticism than 

 that the flood of waters might have been produced through the expul- 

 sion of the same from cavities in the earth. J. E. DeKay, however, 

 writing some years later, ventured to take exception to the views re- 

 garding drift boulders, wisely suggesting that, since the speculative 

 part of geology is but a series of hypotheses, we should in every case 

 admit that which explains the phenomena in the simplest possible 

 manner. To his mind the simplest manner of accounting for these 

 boulders was to suppose that such had been, as igneous material, 

 extruded through the superincumbent strata, forming peaks which 

 have since been destroyed through some convulsion of nature or through 

 the resistless tooth of time, the boulders thus being fragments which 

 had escaped destruction, though their place of extrusion had become 

 completely obscured. 



The observations thus far recorded display a lack of close atten- 

 tion to details and, in some cases, indicate a decided leaning towards 

 cosmogony. Those to which I now call attention were of quite dif- 

 ferent type and show their author to have' been a man of more than 

 ordinary discernment. 



While superintending excavations preliminary to the erection of a 

 cotton mill at Vernon, Conn., Mr. Peter Dobson observed the boulders 

 in what we now call the ground moraine or till, and in a letter dated 

 November 21, 1825, described them as worn smooth on their under 

 side as if done by having been dragged over rocks and gravelly earth 

 in one steady position. They also showed scratches and furrows on 

 the abraded parts. These appearances he could account for only by 

 assuming that the blocks had been worn by being carried in ice over 

 rocks and earth under water. 



These observations seem to have attracted no attention at the time, 

 and even Dr. Edward Hitchcock thirteen years later attached no serious 

 importance to them, although his attention was called to the matter 

 by another letter from Dobson, this time addressed to himself. In 

 this last letter, written in 1838, Dobson described the boulders as 

 having first been rounded by attrition and then worn flat on one side 



