XVI 



TABLE OF CONTENTS. 



of the Archosan rocks arc fossiliferous, and states what tlic life of that epoch 

 must have probably bo(!n, 548 ; his "abundance of life," however, only a theo- 

 retical abundance, 548. All eruptive and cryytalline rockw, excejjt the meta- 

 morphic Palaiozoic and post-PahtiOi^oic, aeoordiug to Dana, "Arehaian " 648 

 649 ; nnphiloso^ihical chai'aetcr of this idea, 549, 550. 



Inquiiy into the propriety of the division of the Azoic (Archaean) into two or more 

 groups, 550-560 ; according to Dana's views, this absolutely necessary, 550. 

 Tiie atterapts.of the Canada Survey to do this on the evidence of fossils, 551 552- 

 the AspiUclla and ArcnicoliicSj 551, 552. Geologi(;al time kept by the order of 

 succession of life, and not by means of minerals, 652 ; the Canada Survey, and 

 the results of its attempts to follow the hitter method, 552. 



How such metliods came to be in vogue, 552. By what principles the Canadian 

 Surv('y was governed, 553, Louan the author of them, 553 ; with what train- 

 ing he began it, 553, 554 ; his age at the time he published his first scientific 

 jjaper, 554 ; the iulluenccs under which he worked, 554 ; he fulluws Lyell 

 implicitly, 555 ; he b(;gins the work with certaiu theoretical assum[)tions, the 

 truth of which he never investigates, 555 ; how his erroneous int(;r[)rotation of 

 the geology of Lake Huron and Lake Superior led him to false conclusions, 556. 

 The Keport of 1863 assumed certain things as having been proved which had 

 not been, 556. Hunt's statements about his own or other jjenple's work not to 

 be acci^pted as authority until his (piotations have been compai-ed with the 

 oiigin.,''. authurities, 550. The (piestion of the noiK;()nfornjity of the Laurontian 

 and Iluroniau looked into, 556 ; what omjiU to hi; seen if tlie two fi,ro uncon- 

 formable, and what is seen, 556, 557 ; Skiavyn'h statements on this point, 557. 

 "What takes [tlacc when eruptive rocks begin to be acted on Ijy erosive agencies, 

 557. What basis of fact underlies the division of the Azoic rocks into two 

 series, 558, 559. Loc.an takes the ground that lithologiiiid characters are suEIi- 

 ci(ait for the arraiig(^ment of J'ocks in chronological order, 559 ; iu accordance 

 with this view, the rocks jireviously called Iluronian still farther dilferentiated, 

 560; the gabbros thus separated, 560; the Hastings scries, demonstrated by 

 Ykxnou to be cojitinuous with the Laui'cntian, made into the ]\lontalban and 

 Taconian, 560 ; the Aivonian, 560. Tabular arrangement of the rocks as at 

 present adopted by the Canada Survey, 561; some im]m>vcraents, and a carrying 

 fai'ther forward of the same idea, suggested in another table, 562 ; eonnnents 

 on this mode of work, 562. Importance to American geologists of having the 

 work of the Canada Survey done according to better methods, 562. 



ArrKNDTX : Exa,mination of some of luvixo's statements, made in the Third Annual 

 Ileport of the United States Geological Survey, 563-565. 



