Reviews 



Report on the Origin, Geological Relations and Composition of the 

 Nickel and Copper Deposits oj the Sudbury Mining District, 

 Ontario, Canada. By A. E. Barlow. (Annual Report of the 

 Canadian Geological Survey, Vol. XIV. Part H, 1904.) With 

 geological maps. 

 Dr. Barlow publishes in this report the results of his careful and exhaus- 

 tive study on the Sudbury nickel district of Ontario. He makes the suc- 

 cession as follows: 



1. Lower Huronian. — No rocks of this age are at present known in the 

 nickel-bearing area, but this period is represented, in part, by the banded 

 siliceous magnetites and associated rocks of the townships of Hutton and 

 Wissner. 



2. Upper Huronian. — (A) Diorites, hornblende-porphyrites, and green 

 schists; (B) conglomerates, graywackes, and quartzites; (C) norite and 

 diorite (Worthington mine belt, and areas southeast of Evans mine and 

 east of Sudbury). 



3,. Laurentian. — Granite and diorite-gneiss near Wahnapitae station. 



4. Upper Huronian ( ?) .—Tuffs, f elspathic sandstones, and slates 

 classified provisionally on previous geological maps as of Cambrian age. 



5. Post-Huronian. — (A) Granites; (B) nickel-bearing eruptive of the 

 main belt (quartz-hypersthene-gabbro or norite, diorite, with their peculiar 

 differentiation product, micropegmatite). (C) dykes of olivine diabase. 



On the accompanying maps the rocks are separated lithologically and 

 are all bracketed under the general heading " Archean." All of these terms 

 are used in the sense commonly given them by the Canadian Geological 

 Survey. The district is closely related with the Lake Superior region on 

 the west, and there the U. S. Geological Survey uses different terms for 

 what are believed to be equivalent series. Barlow's Lower Huronian may 

 be correlated with the Archean of the U. S. Geological Survey; Upper 

 Huronian, with the U. S. Geological Survey Lower Huronian ; Laurentian, 

 with the granites mapped as intrusive into the Huronian of the U. S. 

 Geological Survey ; Upper Huronian ( ?) with the Upper Huronian of the 

 U. S. Geological Survey. 



