Association of American Geologists and Naturalists. 163 



Mr. C, stated that he would here offer a few brief remarks upon the 

 bearing of the facts he had submitted upon the question of the resuUs 

 of aqueo-glacial action in past times, and especially in the effects pro- 

 duced upon subjacent rocks by the stranding of icebergs. It was with 

 much diffidence that he dissented from the opinion entertained by some 

 eminent geologists, that this circumstance had any agency in produ- 

 cing the parallel grooves constituting so remarkable a feature in the 

 rocks of New England. Even assuming that in a former era the drift- 

 ing masses of ice had pursued an uniformly direct course from north 

 to south, though this might explain the general distribution of erratic 

 blocks and bowlders, yet it appeared to him highly improbable that their 

 grounding, and then being driven forward by the combined forces of 

 wind and sea, could ever have produced the furrows in question. There 

 is no reason why the oscillatory or semi-gyratory movement, should 

 not then have followed such an accident as it does now, in which case, 

 as at present, the tendency would be rather to obliterate all such marks, 

 (had they previously existed,) and form a deep hollow if passing over 

 a yielding surface, or a confused scratching and grinding down of a 

 rocky one. It had been shown, however, that the icebergs of the 

 present day pursue a very irregular course, and although their general 

 progress is truly from north to south, or the reverse, yet impelled by 

 varying winds and currents, they deviate widely both east and west of 

 a meridional line. Did not this fact in some measure explain the dif- 

 ference pointed out by Prof. Hitchcock as apparently existing between 

 the line of direction observable in the distribution of bowlders, and that 

 of the diluvial scratches } It had been suggested, that at the period 

 when the drift was deposited there was no Gulf Stream to affect the 

 course of floating ice, but while this may be very true, it does not fol- 

 low that there were no currents whatever. It struck him that to as- 

 sume the production of our parallel grooves by the action of stranded 

 ice, was to presuppose a state of things, a combination of circumstan- 

 ces amounting to a physical impossibility. 



Not only must it be taken for granted that there were no currents, or 

 at least but one from the pole to the equator, and only one perennial 

 wind blowing in the same direction, but the floating masses must either 

 have been of such nicely balanced proportions, and melted with such 

 uniform regularity, and the waves must have struck them so exactly from 

 the same quarter, as to have prevented any change of position ; or they 

 must have been in such numbers and so closely packed as to preclude 

 any oscillatoiy movement. 



Was it essential to the explanation of the phenomena of drift, to 

 assume that the distribution of bowlders, and the production of our so- 

 called diluvial scratches, were entirely the result of contemporaneous 



