MUSEUM OF COMPARATIVE ZOOLOGY. 



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elsewhere, the metalliferous rock is not, as sonictimcs supposed, a real 

 trap rock, but a mixture of trappcan matter, and that of the red sand- 

 stone formation, more or less baked and modified by intense igneous 

 action. These semi-fused materials, in crystallizing, have very fre- 

 quently resulted in the following curious arrangement : the crystalline 

 metallic copper occupies the centre of globular and variously, formed 

 concretions; calcareous spar usually, but not always, invests the cop- 

 per; and very generally the exterior of the kernel is pure crystalline 



chlorite These nodular lumps are dispersed through a base 



which exhibits a sort of pasty mixture of softened red shale and true trap- 

 pean matter ; and many of them are so surrounded as to indicate them 

 to be true segregations from this semi-igneous, semi-aqueous compound." 

 He regarded the sandstone as equivalent to the New lied sandstone of 

 the Atlantic States, and making the same formation throughout the 

 peninsula of Upper Michigan. In a report on the sale pf mineral 

 lands by Mr. Relfe we find the following statement: "In the con- 

 glomerate rocks which overlay the trap, arc to be found all the varie- 

 ties of copper ore of the richest qualities, ofTcring to the smelter a 

 greater yield than ' has ever been obtained from the copper ores of 

 England or other countries that have contributed so largely of this 



important article." * 



Sir Wm. Logan in the Report of Progrcsst regarded the copper-bear^ 

 ing traps of Lake Superior as of a higher antiquity than the Potsdam 

 Sandstone, and attributes the same view to Dr. Houghton in 1841. 

 Logan's statement seems to be erroneous regarding Dr. Houghton's 

 views in this respect. He considered the traps older than rocks which 

 Logan regards as Potsdam sandstone, but of whose age he expressed no 

 opinion in his Report for 1841, to which Logan refers. In 1843, as 

 we have seen before, Dr. Houghton not only took the copper-bearing 

 rocks to be of the age of the Now Red sandstone, but also considered 

 Logan's Potsdam sandstone as belonging to some formation older than 

 the Troutom In this way he had reversed his view of the order of 

 succession in 1843, which Logan attributed to him as late as 1847. 



(L c, p. U.)t 



Mr. Bcla Ilvibbard in his report for 184G§ states concerning the trap 



* Kcporta of Comaiiiices, 29Lh Cong., 1st Scss., Vol. HI., Doc. 591, pp. 2,3, 



1845-46. • 



t Gcol. of Canada, 1846-47. 



t 1849 and 1851, Reports of Progress. Nortli Shore of Lake Huron, p. 20 ; Brit. 



AsHoe., pp. 59-62, 1851. 



§ Senate Documents, 1849-50, III. 371-935, p. 887. 



