285 



substance, more or less extensive, wliicli are frequently 

 met with in metamorphic limestones — varying in amount 

 with the quantity and kind of organic matter which the 

 rock originally contained, and with the intensity and 

 continuance of the heat to which it has been exposed. 

 In some places in Canada, and in the State of New 

 York, therefore, it may still be found in sufficient quan- 

 tity to prove an invaluable source of mineral wealth. 



If what is above said, in regard to the phosphate of 

 lime, be received as a satisfactory explanation of its 

 origin, it will follow that crystalline limestones in which 

 this mineral is found must not only be metamorphic, but 

 must have been deposited in the stratified form, and 

 have once contained the remains of fossil animals in 

 very considerable quantity. 



I may here, in connection with this metamorphic 

 limestone of Canada, mention three facts observed by 

 Mr Logan,^ which are not only interesting in themselves, 

 but which bear upon the important point in chemico- 

 geological theory — the supposed origin of such limestones, 

 to which I have just alluded. These facts are — First^ That 

 while the gneiss above or below the limestone exhibits 

 regular stratification and even lamination, the limestone 

 itself will at times display contortions of the most com- 

 plicated character, and which increase in importance 

 with the thickness of the bed of limestone. Second^ That 

 when this thickness is great, beds of gneiss, of even a 

 foot in thickness, will be bent, folded, and broken, and 

 fragments — sometimes very large — of the gneiss will 

 be surrounded by the white limestone. Third^ That, in 

 one instance, the bed of limestone had an uninterrupted 

 connection with a mass of the same, which filled up a 

 crack or fault in the gneiss, at right angles to the general 

 direction of the strata. In the large, the limestone and 



* Survey of Canada Report for 1845 and 1846, p. 43. 



