E^SUM^, AND GENERAL DISCUSSION. 555 



The latter held that the foliation planes in all gneisses were the results 

 of stratification and proof of deposition from water — the sediments 

 subsequently having been altered by subterranean heat. Those rocks 

 which had been classed as primary, Lyell called hypogene, dividing thera 

 into an tmstratified or plutonic series and an altered or metamorphic 

 series. He also contended that "all the hypogene strata, beautifully 

 compact and crystalline as they are, have once been in the state of 

 ordinary mud, clay, marl, sand, gravel, limestone, and other deposits 

 now forming beneath the waters."* 



Following the above views of Lyell we see Logan at the outset givitig 

 the name "Metamorphic Series" to the older crystalline rocks, assum- 

 ing that the planes of foliation were stratification planes ; and stating 

 that the "syenitic gneiss" or granite possessed "an aspect inducing the 

 theoretical belief that they may be ancient sedimentaiy formations in 

 an altered condition." t Such a belief, if simply looked upon as a the- 

 ory, to be proved or disproved by the light of future evidence to be 

 carefully sought for, would not have done great harm ; but such was 

 not the method of the Canada Survey, whose officers never took one 

 step toward ascertaining the correctness of their theoretical belief. Yet 

 we find Logan declaring, in 1863, that the Geological Survey had 

 shown, in 1846, that the Laurentian consisted of "a series of meta- 

 morphic sedimentary strata underlying the fossiliferous rocks of the 

 province," Hunt, in 1855, making a similar statement-^ 



One who carefully reads the reports of that survey can hardly fail to 

 observe that the entire geology of the crystalline rocks was worked out 

 on the supposition that they were stratified, and that the laws of their 

 relations were those that Logan had employed in the study of coal- 

 fields, a difference in the dip or strike of the foliation being considered 

 sufficient for the establishment of a new geological formation. No 

 examination seems to have ever been made for the purpose of ascer- 

 taining the origin and history of the rocks in question. 



We will now proceed to examine, a little more in detail, the way in 

 which the Azoic or Laurentian rocks came to be divided into two groups 

 — the Laurentian and Huronian. This division originated in the con- 

 founding by Logan of the basaltic volcanic rocks interbedded with the 

 Potsdam sandstone of Keweenaw Point with the basic or greenstone 



* Lyell's Principles of Geology, 1833, 1st ed., III. 367, 374, 376 ; 183-t, 3d ed., 

 IV. 280, 281, 292 ; and all subsequent editions of the Principles and Elements, or 

 Manual. 



t Ante, pp. 331, 332. { Ante, pp. 338, 342. 



