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if the orojanic nature of the Eozoon Canadense can be considered as 

 established, there can be no doubt of the sedimentary character of much 

 of the strata of the system. So also the beds of quartzite and slate, in 

 which the graphite sometimes occur, would in any other system be 

 classified as of aqueous origin. In certain cases of apparent sedimenta- 

 tion, such as the banding of gneisses, this is not so clear since this 

 structure might be induced by other causes, such as pressure, shearing, 

 etc., and we frequently find gneissic structure in true granitic rocks. 

 In fact, no hard and fast theory can be drawn in geological discussion 

 any more than in many other sciences. So much difficulty has been 

 found in drawing the line of division between the two groups of Archean 

 rocks, the Laurentian and Huronian, that very often the two are com- 

 prised under one head, the pre-Cambrian, in which the Cambrian is held 

 to constitute the lowest fossiliferous series,the underlying pre-Cambrian 

 being, in so far as yet known, with the possible exception nientioned 

 above, non-fossiliferous. 



With the primary or paleozoic rocks our acquaintance with the 

 organic life of the globe may be said to begin, though from the ad- 

 ' vanced types of life first found it is held by many that lower and earlier 

 forms must have existed in earlier times, the remains of which have 

 completely disappeared fi'om the record because of the great meta- 

 niorphism to which the rocks of the preceding age have been subjected. 

 Thus ill the lower Cambrian are found the remains of huge trilobites 

 with a length of 17 or 18 inches, in fact of a size unknown or unsur- 

 passed in subs(quent periods. As we advance in Paleozoic time, how- 

 ever, the various species increase with great vapidity, and in some 

 places, judging from their remains, the shores and shallow waters muso 

 have absolutely swarmed with life. That these shores were exposed to 

 the action of sun and wind, tidal currents, etc., is evidenced by the 

 pi'esence of sun cracks, ripple marks and false bedding even in the 

 oldest Cambrian strata, while the presence of beds of conglomerates 

 with sandy layers indicates that the character of the sea beaches of those 

 early days was in many respects very similar to those observed along 

 the coasts at the present time. In fact, in the interpretation of geologi- 

 cal problems in the stratified rocks, sufficient attention is rarely paid to 

 the present shore phenomena, varieties of texture in rook, 2:)assage from 



