47C> REPORT OF NATIONAL MUSEUM, 1904. 



Owen's ideas regarding the tetrahedral form of the earth, though 

 perhaps original with him, and put forward here for the first time by 

 an American writer, were not wholly new. Those desiring a historical 

 review of the subject, with an account of recent advances and theories, 

 will find the same in a paper by J. W. Gregory, The Plan of the Earth 

 and its Causes, first printed in the Geographical Journal for March, 

 1899, and reprinted in the Appendix for the Report of the Smithsonian 

 Institution for 1898." 



At the Montreal meeting of the American Association for the 

 Advancement of Science, for this same year, Logan, referring to pre- 

 vious statements by himself relative to a possible subdivision of Azoic 

 rocks, as given in his annual reports, describes in some 

 subdiVfston oTthe detail a series or group of clastic rocks, consisting of 

 siliceous slate and slate conglomerates, holding peb- 

 bles of crystal line rocks and sometimes showing ripple marks, which 

 he had traced along the north shore of Lake Huron from Sault Ste. 

 Marie for 120 miles, and which has also been noted in other parts of 

 the Dominion by other observers. 



As noted by him on Lake Huron, the formation was some 10,000 

 feet in thickness and plainly of later age than the gneisses, as well as 

 of distinct lithological character. For this formation he then formally 

 proposed the name Huronian, although the term had been previously 

 used in connection with this formation by Murray in 18-18 and Hunt 

 in 1855. To the portion of the Azoic immediately underlying the 

 Huronian he gave the name Laurentian, after the Laurentide 

 Mountains. 



At this same meeting he further suggested a possible subdivision of 

 the Laurentian series, in which the calcareous rocks should be con- 

 sidered as distinct from the siliceous. This announcement and the 

 subsequent discussion led to a mass of literature which is perhaps 

 second only to that involved in the Taconic controversy, although, 

 fortunately, without'any of its bitterness. Indeed, the entire matter 

 is strongly suggestive of Emmons's Taconic, even if the rocks described 

 could not be accurately relegated thereto. 



The principal participants in 'this discussion, which is even now 

 scarcely at an end, were, aside from Logan, K. D. Irving and Alexander 

 Winchell, though many others took part. Later it was apparently 

 shown that under the name Huronian two distinct formations were 

 comprised, to the older of which A. C. Lawson in 1886 gave the name 

 Keewatin.'' 



"Owen's work was briefly noticed in the American Journal of Sciences. Two or 

 three pages of his matter were quoted, and dismissed with "Remarks on these pas- 

 sages are unnecessary." 



b For a history of the discussion, see A Last Word with the Laurentian, by Alex- 

 ander Winchell, Bulletin of the Geological Society of America, II, 1891, pp. 85-124. 



