OBJECTIONS. 43 



cither been worn into those shapes by water, previous to aggregation, or that some of 

 them were concretions. At a subsequent meeting Prof. Wm. B. Rogers expressed similar 

 views, which appear in the published proceedings of the Society. I do not understand 

 these distinguished geologists to have made up their minds very decidedly on the subject, 

 especially as they have not visited the Vermont localities. But objections suggested by 

 gentlemen of such large geological experience deserve serious consideration. 



I have already stated my objections to the theory which they adopt as to the forms of 

 the pebbles. Prof. Rogers suggests as an objection to my views, that the pressure which 

 I suppose to have flattened and distorted the pebbles, has not produced cleavage. But 

 this conglomerate is not a rock in which cleavage is ever found. It is a foliated or schist- 

 ose rock. It has joints in it, such as prove very clearly that it was once in a state more 

 or less plastic ; but these (the most perfect ones especially) cross the folia nearly at 

 right angles, and could never have been produced by pressure. It is a fact, however, that 

 'some of the larger pebbles, particularly at their extremities, do show the commencement 

 of a schistose structure probably the result of pressure. Yet the facts do not require us 

 to suppose the pressure on this rock to have been of the most powerful kind. In some 

 cases, indeed, as at Plymouth, the pebbles are compressed into folia ; but in general they 

 are only moderately flattened, and sometimes not at all. If only moderately plastic, such 

 effects could not have required a very enormous force. 



Another objection is, that the compression has not distorted the fossil Lingula3, found 

 in the pebbles on Taunton river and at Newport. But I am not aware that the pebbles 

 in the conglomerate of Taunton river have been compressed and elongated ; nor have 

 they been, in but a part of that around Newport. Whether they have been in the 

 particular pebbles containing the fossils, I am unable to say. A third objection rests 

 upon the fact that some of the pebbles have scarcely been flattened at all, and their 

 longer axes cross the foliation ; though I do not myself recollect to have seen any whose 

 position was much awry. But some of them, on account of their composition, may have 

 been scarcely at all plastic, or had such a position that the pressure affected them but 

 slightly. We certainly ought to expect such cases. 



I have been led of late to a re-perusal of the able papers that have appeared for several 

 years past in the English Journals, on cleavage, compressed and distorted fossils, and 

 particles of slate, by Sharpe, Sorby, Tyndall, Scrope, Scheerer, and Haughton. The 

 result is, a conviction that the facts which I have given respecting the conglomerates are 

 only another phase of the phenomena described by these eminent geologists. If the facts 

 they adduce prove the elongation and expansion of slate, limestone, and fossils, as is 

 generally conceded, although proved mainly by the microscope, why should we think 

 it strange that the like effects may have been produced upon conglomerates, so as to 

 show themselves on a large scale, and to unaided vision ? The manner in which the 

 veteran geologist Scrope supposes gneiss and mica schist may have been formed out of 

 granite (which he has illustrated by figures, Phil. Magazine, Vol. LI. p. 196), whatever we 

 may think of the hypothesis, corresponds very nearly with some of my suppositions, or 

 rather facts, as to the conversion of conglomerates into the schist. And the ideas of 

 most of these writers as to the former plastic condition of most of the rocks, correspond 

 with those which I have expressed. If I am wrong then, I have the consolation of being 

 in good company. 



