42 FLATTENED CONGLOMERATES. 



and this fact, in connection with all the rest which have been adduced, affords a presump- 

 tion that feldspar in nearly all the crystalline rocks, stratified and unstratified, is a 

 product of metamorphism. 



We will add a few words as to other localities of conglomerates with flattened pebbles. 

 It is only so recently that the full denouement of the subject has opened upon us, that we 

 have not had time to visit others. But we happen to have specimens from Bernardston, 

 Mass., in which the elongation and flattening are decided, in a conglomerate micaceous 

 schist connected with clay slate and quartz rock. The same is true to some extent in a 

 like rock from Bellingham, Mass. Still more decided is it in bowlders of the conglomerate 

 syenite described above from Northampton ; as it is also in the same variety of rock on 

 Little Ascutney. In fact we predict that this phenomenon will be found present in very 

 many of the thoroughly metamorphic conglomerates, although not noticed by observers 

 because their attention was not called to it. 



Less than a mile north of the conglomerate locality in Plymouth, Vt., on the east side 

 of the Pond, and nearly on the strike of the conglomerate, occurs a remarkable variety 

 of marble in an unstratified bed several rods wide. It consists of a ground of dark 

 limestone, through which are disseminated numerous elongated masses from half an inch 

 to six inches long, and from a quarter of an inch to an inch wide, of white semi-crystal- 

 line carbonate of lime. Their longer axes lie as nearly parallel to one another as those 

 of the quartzose conglomerate. What their origin was I have scarcely ventured to 

 conjecture. One naturally inquires, however, whether they may not be elongated organic 

 remains, such as corals. At any rate the inquiry may be worthy of consideration 

 whether they are not something elongated by the same force that has acted on the not far 

 distant conglomerate. This idea did not occur to me when in the vicinity, and therefore 

 I did not go to determine the point. If there be any foundation for this suggestion, we 

 should expect that the longer axes of these nodules would correspond more nearly with 

 the dip than with the strike. I have not the slightest recollection whether it is so. 



The chief interest in the facts and conclusions in the preceding discussions, lies in the 

 light they cast upon metamorphism. We had indeed felt that there was a good deal of 

 probability in the general doctrines of metamorphism advanced by able men. But never 

 before have we had the various steps of the process brought directly under our eyes, and 

 so distinctly as to confound our scepticism and challenge our belief. Instead of any prej- 

 udices in favor of the conclusions to which we have been brought, our prepossessions 

 have been the other way. But we could not resist evidence so clear, and we find that our 

 new views greatly eclaircize the subject of metamorphism. It seems to us difficult to 

 conceive how geologists can avoid the conclusions we have presented, if they will visit and 

 study the localities we have pointed out. And yet we know very well how different im- 

 pressions are made by the same facts upon different minds, equally able and apparently 

 equally impartial, and therefore we expect the views we have presented will be controver- 

 ted. But time will'bring out and establish the truth. 



March 20th, 1861. A brief and important summary of the preceding facts and 

 arguments having been presented by me last autumn before the Boston Society of Natural 

 History, Dr. Charles T. Jackson expressed his dissent from my views as to the manner in 

 which the pebbles had been flattened and distorted, and his conviction that they had 



