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XIV 



TABLE or CONTENTS. 



JONES'S SURVEY. 



COMSTOCK on the Azoic locks of Northwestern Wyoming, 515. 

 than litholo^dcal for calling these rocks Laurcutiau, 515, 516, 



No reasons other 



POWELL'S SURVEY. 



Report hy Newton and Jenney on the Black Hills, 516 ; the Azoic rocks divided 

 into Laurentian and Huronian, hnt on very slight evidence, 516. 



CALIFORNIA. 



Results of the California Survey, 516, 517. Hunt's views in 1866, and in 1868, 

 before visiting the region, 517. He spends several days there, ami discovers 

 that ro.^vs of the Sierra Nevada whicai contain Jurassic fossils are of Huronian 

 ,<^e, 517, 518. Hunt's views of Califoniian geology shown to be iundamentally 



a 



wrong, 518. 



PAET II. 



Ei^suirf;, AND General Discussion. 



Introductory remarks, 519. The geology of CaimJa aud Ne^y England in an almost 

 Ipelc.^ state of confusion, 619, 520. How this condition of t ungs has been 

 hvoucdit about 520. The establishment of the Silurian System by MURCIIISON, 

 in ] sV. or.cns the way to the discussion of the .luestion whetlun- the lowest lumt 

 of life'lKul been reached, 520. First use of the term Azoic by. Mmuu.LSON, m, 

 521- his dehnition of thn,t term, 621; his hesitating and contradictory statements 

 in regard to it, 521 ; his gradual withdrawal of it in the successrve ediUous of 

 SiluHa, 521, 622. BA.a.ANDE's grouiung, iu 184G, oi the Protozo.c and Azo.c 

 rocks 522 ; confusion caused by the use of the term Cauibnan already begun .,22. 

 FosTia-. and Whitney, in 1851, describe certain rocks on the south shore o Lake 

 Superior, under the designation of the Azoic System, 622. Srnular roeks,^ ,n 

 Canada, called by LooAN the Metanmrphic Series, but without lully aseer tarning 

 their geological position, 523. LooAM, in 1864, applies the name LaurenUan to 

 these rock:, 523 ; confusion introduced by his inabihty to d.stmgmsh between 

 the Azoie and the Pakeozoic, 523. The term Azoic for some tm,e i" «"-;"* "- 

 in this country, 523, 524; Dana's use and defnrition of it in 18«2 and 18.1, 624; 

 his views in regard to tlu. <.xisleuce of life during an " azoic period, 524 ; the 

 position assumed by bin, in 1874, and the introduction of tlu, term An a^ij, 

 lith a delinition of it, 524. Confusion of views m regard to the older ciys 1- 

 lin<. rocks, 525. Some general remarks introductory to the consideration of the 

 II 5 5 ; great interest attaching to the question whether life exists m other 

 worlds tlian our own, 625 ; importance of fixing the epoch when life began here, 



