24 FRANK D. ADAMS 



been worked out and the full succession given in the table has yet been found. 

 Also when the succession was originally worked out all available information in 

 reference to Canada as a whole was considered and it was suggested that within 

 the regions about Hudson Bay and the Copper Mines Rivers, the equivalents 

 of at least two divisions of the Huronian and of the Keweenawan appeared to be 

 present.' 



As to the question of a floor for the Keewatin, according to our view, the 

 Keewatin is simply the most ancient series which has been discovered to the 

 present time. Naturally being the oldest series discovered, we have not yet 

 found the rocks upon which it was laid down, and we make no assumption in 

 this matter. Dr. Adams speaks of the Keewatin as a sedimentary series. If 

 he means by this that it is a series laid down at the surface, this characterization 

 is correct. However, we have frequently pointed out that this series is essentially 

 composed of igneous rocks, including both lavas and fragmentals, and is only 

 very subordinately of ordinary sediments. 



As to the position of the Grenville series, I hold my opinion in resers'e. INIiller 

 and Knight have shown that in the Hastings district where the series which 

 Adams places in the Grenville is most extensively developed, there is an uncon- 

 formity in the sediments. It is their belief that the greater part of the Hastings 

 sediments, including the great limestone of Adams, belongs above this uncon- 

 formity, below which is the Keewatin. If they are correct in this view, the larger 

 part of the Hastings series included in Adams' Grenville belongs not with the 

 Keewatin but with the Lower or Middle Huronian. 



Dr. Adams says in reference to correlation by diastrophism: "This will con- 

 stitute a great advance as compared with our present methods, which afford no 

 adequate means of determining the relative values of unconformities, and thus 

 the successions in the most distant parts of the world are now being matched with 

 each other and an unwarranted satisfaction is manifested if the number of uncon- 

 formities in the pre-Cambrian succession in different continents is approximately 

 identical, and a sure and certain hope that all will prove to be satisfactory is 

 expressed if there is no agreement." 



In my address before the Geological Society of America a year ago, I intro- 

 duced the table of pre-Cambrian series for China with their separated uncon- 

 formities as given by WiUis. I remarked that the Lake Superior Algonkian 

 series in their number and their separating unconformities present a remarkable 

 similarity to the Algonkian of China, but said it would "not be well to too strongly 

 emphasize the close correlation suggested." Also I mentioned the "possibility 

 that in the future we may be able to correlate the unconformable series of the 

 Algonkian in provinces separated as far from one another as the Lake Superior 

 region and Northern China." ^ 



I Charles R. Van Hise, Bull. 86, U. S. G. S., pp. 496-502, 1892; l6th Annual 

 Report, U. S. G. S., Part I, pp. 807-9, 1896. 



^ "The Problem of the pre-Cambrian," Btdl. Geol. Soc. oj Am., Vol. XIX, p. 29. 



