SOME PRE-CAMBRIAN LITERATURE OF NORTH AMERICA 467 



north from the north end of Lake Temiskaming, is similar to that 

 of the Cobalt district. Narrow gold-bearing quartz ankerite veins 

 are found cutting Keewatin and Huronian rocks in the Oposatica 

 district. The gold minerals are petzite and native gold. The 

 petzite occurs in cracks in the quartz and ankerite, and the native 

 gold was deposited after the petzite. Harvie believes that the 

 Oposatica ores will show no increase in values with depth, since the 

 Tellurides in known districts have all been found below the 

 weathered zone. 



Hore^ discusses the stratigraphy and the ores of the Cobalt 

 district. The richest ores have been found in the Huronian con- 

 glomerate. Rich shoots have also been mined in the Keewatin 

 greenstone, and in the Keweenawan diabase. The ores are geneti- 

 cally connected with the diabase intrusions. • 



Hore^ argues that the cobalt silver ores, and the aplites and 

 diabases with which they are associated are all differentiation 

 products of one magma. 



Hore^ beheves that the glacial and glacio-fluvial origin of a por- 

 tion of the conglomerate-quartzite-shale series of Huronian age at 

 Cobalt and Temagami is clear. The evidence consists in the small 

 amount of stratification, the presence of striated and soled pebbles, 

 the heterogeneity of the conglomerate, and the discordance between 

 the lithologic character of the conglomerate and the basement on 

 which it was deposited. The basal conglomerate may not be of 

 glacial origin since they are like the materials on which they lie. 

 Some of the materials are probably water deposits, into which large 

 erratics were introduced by floating ice. Certain thick bowlder-free 

 deposits of shale and graywacke are probably ordinary water-laid 

 sediments. 



Hore"* states that Keewatin and Huronian rocks similar to those 

 of the Nipissing area outcrop in the Porcupine district. The 



' R. E. Hore, "Geology of the Cobalt District," Trans. Am. Inst. Min. Eng., 

 XLII (1912), 481-98. 



= Reginald E. Hore, "Differentiation Products in Quartz Diabase Masses of the 

 Silver Fields of Nipissing, Ontario," Econ. GeoL, VI (1911), 51-59. 



3 Reginald E. Hore, "Glacial Origin of Huronian Rocks," Jour. GeoL, XVIII, No. 

 S (i9io),pp. 459-67- 



•* Reginald E. Hore, "On the Nature of Some Porcupine Gold Quartz Deposits," 

 Jour. Can. Min. Inst., XVI, No. 15, pp. 57-70. 



