32 PROCEEDINGS OF THE CANADIAN INSTITUTE. 



extent may be pursued. The origin of these rocks (the Laurentian) 

 is still veiled in mystery, though it is generally conceded to have 

 been a metamorphic one. Deposited in prepalseozoic seas, in simi- 

 lar manner to the later stratified rocks, they are supposed to have 

 been subjected to the agencies of subteri'anean heat and vapour at 

 high pressure, and of eruptive overflows. By such ti'eatment they have 

 become so metamoi'phosed that their stratification and chemical com- 

 position alone point to their sedimentary origin and character. They 

 are highly crystalline and often much folded and contorted, and con- 

 sist of quartzite, gneiss, pyroxene and other related silicious rocks. 

 Traversing these, however, are to be found strata or bands of crystal- 

 line limestone and dolomite — the limestone often highly coloured — 

 together with beds of many economic minerals. These latter con- 

 sist principally of iron ores, graphite and apatite. It is always in 

 connection with these bands of limestone that the phosphate is found, 

 and therefore they have acquired the name of the " Phosphate-bear- 

 ing Rocks." 



These ai'e especially rich in the townships of Templeton, Hull, 

 Buckingham and Wakefield (Ottawa Co.), Quebec, and North 

 Bui'gess, Elmsley and adjoining townships in Ontario. These two 

 districts are most probably, geologically speaking, one — the charac- 

 teristics presented by one being recognizable in the other for the 

 gi-eater part. In the former district the rivers Gatineau, La Blanche 

 and Aux Lievres run, and in their valleys the largest deposits lie. 

 By a reference to a map of Ottawa County it will be seen that the 

 La Blanche at a distance of some ten miles from the Ottawa River 

 widens into Lake McGregor, and proceeding northward we find a 

 succession of narrowings and widenings — so typical of many of our 

 I'ivers — forming a chain of connected lakes till we I'each the northern 

 boundary of Wakefield. This district is especially rich in phosphate, 

 as is the district between the La Blanche and Aux Lievres, where 

 the Dominion Mining Co. and the Montreal Mining Co. have made 

 extensive operations. 



The origin of apatite is as debatable ground as that of the rocks 

 in which it occurs. Many are fond of ascribing to phosphate an 

 organic source and seem to see a necessary connection between phos- 

 phorus in its compounds and animal life. Prof. G. M. Dawson sug- 

 gests its formation from coprolitic layers, becoming crystalline by 



