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In the Laurentian rocks — which are those characterizing the gr^at 

 ^country to the north of the Ottawa, and elsewhere veiy largely developed 

 in Canada — we have a great volume of sediments, deposited in an 

 ocean of vast antiquity, the earliest in fact of which we find any traces- 

 These sediments which, no doubt, originally resembled in their main 

 features those of later ages, have since been so completely metamorphosed 

 that their materials have entered into new combinations among them- 

 selves and become entirely crystalline. "While, thei-efore, still consisting 

 of the matericds originally deposited, they I'esemble them as little in 

 appearance as do the crude ingredients of glass the finished product. 

 There can, however, be no doubt of the original sedimentary origin of 

 these Tjaurantian rocks, the change from muds and sands — and I would 

 also include contemporaneous volcanic materials — to wholly crystalline 

 rocks such as these, is seen in less metamorphosed formations in various 

 parts of the earth's <;rust, and has been traced in all its stages. If, 

 therefore, ordinary limestones were originally present in these old i-ocks, 

 we would expect them now to have assumed a wholly crystalline 

 character, and to appear as marbles. Contained beds of a peaty or coaly 

 nature might be expected to pass into crystalline carbon or graphite, 

 and phosphatic nodular or copi-olitic layers could appear only as 

 crystalline calcic phosphate or apatite. As a matter of fact we find 

 all three of these substances in the Laurentian, and though the proof 

 may not be absolute that their origin and appaarance -was at first the 

 same as that of analogous materials in the newer rocks, the evidence is 

 all in that direction. 



The main facts in regard to the mode of occurrence of these 

 deposits of apatite in Canada, so far as our knowledge goes, mus*; be very 

 briefly presented. Some of the be:ls in the Laurentian series are found 

 to be comparatively rich in apatite, crystals and crystalline masses of 

 this mineral being scattered through them. This is the case in some of 

 the marbles, occasionally in the iron ores, and also particulai'ly in 

 connection with the pyroxenic rocks. In addition to these, in which 

 the apatite may be considered as generally distributed, certain layers, 

 apparently of the character of beds, occur, consisting of nearly pure 

 apatite, or containing so large a proportion of the mineral as to pay for 

 working. Still further, we find distinct veins and fissures which have 



