Theoretical Considerations. 241 



The appearance of a concretionary structure is so marked in some 

 specimens, that one or two geologists, for whose opinions I entertain 

 a high respect, have even suggested whether this remarkable sub- 

 stance be a real petrifaction ; and enquired whether it may not be of a 

 nature similar to the columnar limestone, described by Capt. Bonny- 

 castle with a plate, in the 20th volume of the Am. Journal of Science. 

 Judging from the plate, as well as specimens which I have seen of 

 that limestone, I am satisfied that the specimens from Springfield are 

 of a very different character, and exhibit far more marks of organic 

 structure. Indeed, I cannot doubt but they are real petrifactions ; but 

 having examined Goldfuss' Petrefacta, Miller's Crinoidea, Sowerby's 

 Mineral Conchology, Parkinson's Organic Remains, &c. I can find 

 no fossil resembling these. Yet I doubt not but some one more con- 

 versant with this subject, will be able to refer them to their proper 

 place. General analogies only, have led me to regard them as hav- 

 ing resulted from the petrifaction of radiated animals : though I am 

 by no means sure that they are not of vegetable origin. 



The specimens, Nos '265 and 263, were obtained from the shale 

 that forms the north bank of Westfield river, in West Springfield ; 

 and from their general aspect, I suspect them to be Encrini : though 

 they may be of the same nature as the remains just described. The 

 mineralizer in this case seems to be argillo-ferruginous limestone, ex- 

 cept the central part. 



Whether the Nos. 283, 284, are to be regarded as organic relics, I 

 feel unable to decide. 



Theoretical Considerations. 



The new red sandstone series that has been described, consisting 

 chiefly of the fragments of older rocks from the surrounding region, 

 must obviously have been produced chiefly by the agency of currents 

 of water, which first wore away these rocks, and then transported 

 and deposited the fragments where we now find them. By what 

 agent or agents their consolidation was effected, we may not be able, 

 perhaps, in the present state of geological science, to determine. We 

 do know, however, that water, air, and heat, may all, under certain 

 circumstances, accomplish this work. Water may contain in solu- 

 tion some cement, say carbonate of lime, which shall be deposited in 

 the interstices between water worn fragments and thus unite them. 

 Air, it is also well known, by abstracting water from some of the ma- 

 terials that form rocks, does sometimes effect their consolidation. 

 31 



