AMERICAN GEOLOGISTS AND NATURALISTS. 57 



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

 effects produced upon subjacent rocks by the stranding of iceber"-s. 

 It was with much dilhdence that he dissented from the opinion en- 

 tertained by some eminent geologists, that this circumstance had 

 any agency in producing the parallel grooves constituting so remark- 

 able a feature in the rocks of New-England. Even assuming that 

 in a former era the drifting masses of ice had pursued a 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 fol- 

 lowed 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 fonri a deep hollow, if passing over a yield- 

 ing surface, or a confused scratchiug 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 

 difference pointed out by Professor Hitchcock as apparently existing 

 between the line of direction observable in the distribution of bowl- 

 ders, 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 follow that there were no 'currents whatever. It struck him 

 that to assume the production of our parallel grooves by the action of 

 stranded ice, was to presuppose a state of things, a combination of 

 circumstances, 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 peren- 

 nial 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 nimibers and so closely 

 packed, as to preclude any oscillatory 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 contempora- 

 neoiis action ? Might there not have been a period when the northern 

 portion of our hemisphere was covered with glaciers resembling those 

 of the Alps, during which the furrows were produced by their gradual 

 and radiohnear advance, followed by one of drifting ice, (whether 

 borne along with a sudden rush of waters, caused by a paroxysmal 

 elevation of land in the vicinity of the pole, or floods resulting from 



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