44 REVIEWS — ACADIAN GEOLOGY. 



Permian trap of Connecticut, New Jersey and other States of the 

 Union, in the same trap of Nova Scotia, of Baumholder in Khenish 

 Prussia, &c, becomes clearly intelligible ; whilst, on the electro- 

 chemical theory, its connection with this igneous rock, as truly 

 stated by Mr. Dawson, is without any obvious explanation. This 

 alone would be a strong argument in favor of its igneous origin ; and 

 when we consider the enormous amount present in the Lake Superior 

 trap, and the absence of secondary products, such as must have re- 

 sulted from the precipitation of this immense volume of metal from 

 an aqueous solution, the case becomes still further strengthened. 

 The only real objection to the igneous view, arises from the presence 

 of zeolites and calc-spar, often in the closest association with the 

 copper. Allowing the zeolites present in most traps, to be, as a 

 general rule, after or secondary products arising from a decomposing 

 process in the trap itself, we cannot obviously apply this argument 

 to the copper. We know furthermore that many basalts — tough and 

 unweathered — actualby contain both zeolites and carbonates as con- 

 stituents of their mass. That such constituents, moreover, cannot 

 in all cases at least, be the result of alteration and decomposition, is 

 plainly proved by the presence of metallic iron in certain basalts, as 

 shewn by the interesting researches of Dr. Andrews. Nay, our 

 author himself, in a very able discussion of the facts connected with 

 the formation of the iron veins of the Cobequid Hills, assigns to 

 an7ce?-ite—a compound of the isomorpbous carbonates of lime, pro- 

 toxide of iron, and magnesia — an eruptive or igneous origin. His 

 views, in this respect, may not meet the approbation of all geologists, 

 but we regard them as perfectly legitimate. An extensive examina- 

 tion of very numerous specimens of vein-stones and mineral aggre- 

 gations, with particular reference to this question, has established in 

 our mind the firm conviction that carbonate of lime does at times 

 undoubtedly originate, or crystallize, from a directly igneous source. 

 Indeed, all modern researches tend to shew, that there exists in 

 nature scarcely a single mineral substance which is not sometimes 

 produced by aqueous and sometimes by igneous agencies. With 

 regard to the occurrence under particular conditions of hydrated 

 minerals and carbonates in trap rocks, we may call to mind that 

 volumes of steam and emanations of carbonic acid are largely given 

 off from modern lavas, not immediately after their transmission from 

 the volcanic orifice, but so soon as their temperature has cooled down 

 below a certain point. If, by various readily-conceivable causes, the 

 emission of these products be prevented, the formation of hydrated 

 and carbonated compounds becomes a necessary result. In certain 

 Btnean lavas, known by the somewhat loosely-applied term of Cyclo- 



