REVIEWS 915 



series. The Laurentian rocks consist of gneisses and granites with 

 some schists ; the Huronian, of ferruginous quartzite interbanded with 

 hematite of good quality and varying in character from soft red to 

 specular. The Animikie formation is the most widespread. A deep 

 red dolomite, varying from a rather heavy bedded, compact, fine- 

 grained rock to a coarser shaly variety, is the most important litho- 

 logical unit. Associated with the dolomite is a highly ferruginous 

 dolomitic sandstone which locally carries angular masses of quartz. 

 Conformably overlying the red dolomite, on the Upper Spruce river, 

 is a fine-grained, non-fossiliferous, greenish-gray shale, which is capped 

 by fifteen feet of trap. Trappean flows, probably gabbroid, occasion- 

 ally reaching a thickness of 300 feet, overlie the sediments for the 

 most part, but are in places interbedded with them. In the eastern 

 half of the Nipigon area the Huronian schists pass into jasper and 

 hematite and form three iron ranges, one north and two south of 

 Sturgeon river. Animikie traps are abundant in this area, and show 

 about the same relations to the sedimentary series as in the western 

 half. The explorations of D. B. Dowling in the region to the west of 

 James bay have shown that the Paleozoic area beginning at the 

 southern extremity of James bay extends uninterruptedly along the 

 coast to cape Churchill in Lat. 59 N. The rocks of the newly 

 explored area in the angle between James and Hudson bays are of 

 Silurian age. To the southwest of Cape Henrietta Maria is a consider- 

 able area of Animikie rocks consisting of ferruginous slates and jaspers 

 capped by trap. 



Work in the vicinity of Lake Abitibi near the Ontario-Quebec 

 boundary resulted in the more accurate mapping of the pre-Cambrian 

 rocks. A. E. Barlow has added many important details to the recon- 

 naissance work done in Denison, Graham and Creighton townships 

 of the Sudbury mining region in 1890. The unaltered rock of 

 the nickel-copper deposits is a.quartz-hypersthene-gabbro or norite. 

 The pyrrhotite, chalcopyrite, and pyrite.were original constituents of 

 the magma. In the process of slow cooling of these norite masses a 

 species of differentiation resulted in the segregation of the sulphides 

 "so that the final solidification saw the ore-bodies under very much 

 the same conditions as at present obtain." Associated with the norite 

 in the ore-bearing ranges are micropegmatites which are undoubtedly 

 differentiated portions of the nickel-bearing eruptive, as there is a 

 perfect transition from one rock type to the other. There are three 

 distinct bands of the norite and associated micropegmatites. Of these 



