TABLE OF CONTENTS. 



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PAET I. 



Synopsis oi^^ the Evidence on which the Rocks of the Azoic 

 System have been vakiously gkoufed into Distinct Divisions 

 BY American Geologists. 



CANADA. 



The " MetJiTDorplilc Series" of Logan, as defined by Mm in tlie Report of 1845-46, 

 331 ; his two divisions of the same, based only on theory, 332 ; his description 

 ^ of the Metamorphic Series on' the north shore of Lake Superior, in tlie Report of 

 1846-47, 333 ; Hunt's subsequent niisreproseniaiion of Logan's views, 334. 

 MuiiiiAY's description of the formations of the Kamanistiqnia Basin, 334 ; the 

 two series of rocks subse(iuently known as the Laurentian and Huronian shown 

 by him to be conformable, and to pass imperceptibly into each other, 334 ; this 

 fact not mentioned by Hunt in his account of Murray's Report, 334. Murray's 

 description of the rocks on the north shore of Lake Huron, Report of 1847-48, 

 335. Louan's description of the same, in 1848, 335, 336 ; he confuses the 

 Azoic rocks of Lake Huron with the Taheozoie of the south shore of Lake 

 Superior, 330 ; Hou(;irroN'.s views misrepresented by Logan, 336. Murray, 

 in U(!port for 1848-49, again d(\seribes region north of Lake Huron, 337. 

 Logan, in 185-2, calls these rocks Cambrian, 337. In the Report for 1852-53, 

 published in 1854, Logan gives the name "Laurentian" to the rocks pre- 

 viously designated byhhu as *' Metamorphic " or Cambrian, this name being 

 the e(piivalent of the term Azoic, previously introduced by Foster and Whit- 

 ney, 337, 338 ; the term " Huronian" first used, by Hunt, in 1855, 338 ; the 

 Huronian said Ity him to be unconformable with the Laurentian, 338 ; this an 

 error, base.l on the eonfounding, by Logan, of the Azoic of- Lake Huron with 

 the Paheozoic of Lake Superior," 338. First mention of the Huronian in the 

 Canada, Rept)its, 338, 339. The relations of the Laurentian and Huronian indi- 

 cated in R(^port for 1856, 339 ; relation of the hypersthene rock, since called 

 *' Norian," indicated by Hunt, 1855, and again in 1856, 339. Division of the 

 Azoic into Laurentian and Huronian, and the name Laurentian opposed, and 

 Logan's entire misconception of the geology of Lake Huron and Lake Superior 

 pointed out by Whitney, in 1857, 340; Logan recognizes his mistake, but 

 does not abandon the terms introduced by him, 340 ; further statements of 

 Logan (1857) in regard to the Laurentian and Huronian, 340, 341 ; peculiar 



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