18 Professor A. P. Coleman — The Sudbury Nichel-Ores. 



Layer No. 6 corresponds to the lower Mytilus band in the sections 

 F to Gr and again at L. It is the upper kitchen midden of 

 Mr. Warren, and contains some stones that appear to show the action 

 of fire, but no burnt earth. Land shells occur plentifully just above, 

 in, and immediately below it. 



Both this band and No. 8 are limited in extent, covering about 9 feet. 



The latter much resembles the true kitchen midden at E, only no 

 trace of a regular hearth is seen, and though quite as black when 

 first dug out its contents, except the charcoal, dry paler. Besides 

 Mytilus it yielded shells of Patella and Purpura lapillus, but no traces 

 of land molluscs. 



It is rather remarkable that no mention of these two interesting 

 cooking sites is made in the Geological Survey Memoir, although. 

 Mr. Warren pointed out their existence three years before that work 

 appeared. Judging, however, from the scant notice of Mr. Warren's 

 paper, obviously inserted after the memoir had been written, the 

 compiler not only was unacquainted with it at the time he visited the 

 spot, but did not even make himself properly acquainted with it 

 afterwards. 



[To be concluded in our February Number.) 



III. — The Sudbuky Nickel-Ores. 

 By Professor A. P. Coleman, of the University of Toronto. 



IN Professor Gregory's interesting presidential address contained in 

 your journal for October, there is a reference to the origin of the 

 Sudbury ores, in which he expresses the opinion that they were 

 deposited from solution long after the first consolidation of the rocks 

 with which they are associated. As the Sudbury ore deposits are 

 perhaps the best examples in the world of the magmatic segregation of 

 sulphide ores it seems a pity that the weight of Professor Gregory's 

 authority should be given against the correct view. Probably he has 

 not read the reports on the region by Dr. Barlow and myself in which 

 incontrovertible proof of the magmatic origin of these ores has recently 

 been given. ^ In the report prepared by myself it is shown that all 

 the ore bodies are found at the lower edge of a laccolithic sheet of 

 norite, blending upwards into micropegmatite, or on dike-like pro- 

 jections from this sheet. The laccolithic sheet is 37 miles long, 

 17 miles wide, and has dozens of ore bodies connected with its basic 

 edge. The adjoining rock may be granite, gneiss, green schists, 

 graywacke, etc., without affecting in any way the monotonous character 

 of the ore. The ore bodies may contain fragments of the adjoining 

 rocks and sometimes also of the norite, for some crushing and faulting 

 has taken place ; but everywhere the solid ore passes into pyrrhotite- 

 norite, and then into norite spotted with blebs of ore. The sulphides 

 have shai-p boundaries against the adjoining rocks, but blend into the 

 norite. The blebs of pyrrhotite may be found hundi-eds of yards from 

 the ore bodies and completely enclosed in the norite with no fissure or 



1 Barlow, Ann. Rep. Geol. Surv. Canada, part II ; Coleman, The Sudbury 

 Nickel Field, Bur. Mines, Ontario, vol. xiv, pai-t 3. 



