222 Letters of Mr. Brongniart, with remar%s, 



these, that the fish were found at Westfield, beneath argil- 

 laceous sand-stone. Now, throughout this whole trap form- 

 ation, copper is found — principally in the sand-stone rock 

 beneath the trap. It is in the form of copper pyrites, of 

 oxid of copper, of green and blue carbonat, and of native 

 copper.* Many shafts have been opened for working it, and 

 the Connecticut state's prison for convicts is in the aban- 

 doned pits and galleries, wrought many years ago, for cop- 

 per, in the sand-stone beneath the trap, in the township of 

 Granby in Connecticut. The existence of the copper then, 

 in this region, fulfils another condition of resemblance be- 

 tween the countries alluded to by Mr. Brongniart, and those 

 in this region. We would add, that although no more fish 

 have been obtained at Westfield, because the pit has long 

 been filled with water, they have been found in various oth- 

 er places in the same formation. Particularly at Sunder- 

 land in Massachusetts, in rocks that pass under Connecticut 

 river ; they were discovered by that excellent observer, Mr. 

 Edward Hitchcock, who says they are very numerous. 

 They are found in the argillaceous sand-stone. The addi- 

 tional interest imparted to our trap region by the remarks 

 of Mr. Brongniart, with the pecuhar nature of the country, 

 vs'ill, we trust, induce some of our geologists to examine the 

 entire formation with more scrupulous care, and to give a 

 connected report of the whole. It is a feature almost «n- 

 ique, in American geology, and should not be allowed to re- 

 main without a complete and skilful delineation, especially 

 as the prehnite, zeolite, chabasie, analcime, laumonite, chal- 

 cedony, agate, &;c. which are found imbedded in the trap, 

 impart an additional interest to the research. 



We return to Mr. Brongniart' s letter : — 



"The compact blackish limestone from the environs of 

 Lake Ontario, contains petrifactions, which I have not yet 

 been able exactly to determine. I suppose that there is one 

 species of Orthoceratite, and I observe among them many en- 

 trocites. But these generic determinations are too vague, 

 and therefore ever inadequate. The case is the same 

 with the sand stone of Cayuga, containing terebratulites of 



* For some remarkable examples of very fine specimens of the latter, see 

 ■\'ol. I. pa. 55, of this Journal, and Bruce's Journal, pn. 149; the former of 



'he?e piece? ^veig^hefl si's:, and thp Intter ninety poimds. 



