THE 



GEOLOGICAL MAGAZINE, 



NEW SERIES. DECADE V. VOL. V. 



No. XI.— NOVEMBER, 1908. 



ORIG-insr-A-H, ^^E-TICLES. 



I. — Van Hise on the Division of the Pee-Cambeian. 

 By Alfred C. Lane, State Geologist of Michigan, U.S.A. 



WHEN President Yan Hise finished his address before the Geological 

 Society of America last winter, which the Society has just 

 issued, he leaned over benignly and glanced at Dr. Coleman, Professor 

 Lawson, and myself, and said that while it was not customary to 

 discuss the President's address he hoped in this case the custom would 

 be waived, as he knew a number of members disagreed with him, and 

 he felt they would have criticism of value to contribute. Whereupon 

 ensued a most friendly but lively discussion, in which many took part. 

 It has not been the custom of the Society to report such discussions, 

 but I am sure that Yan Hise will not object to see some of the points 

 raised by the writer in print, as well as his Address. 



The writer believes that the Keweenawan is Cambrian, and stands 

 in somewhat the same relation to the Georgian and Acadian as does 

 the Old Eed Sandstone to the Devonian of the Eifel, or the Permian 

 and Trias, with their lavas, to the Alpine facies of the same beds. 

 This belief is shared with Professor Seaman, of the Michigan College 

 of Mines, and N. H. Winchell, and we are as conversant with the 

 facts as any. 



It is true no fossils have been found, and that the extreme Upper 

 Cambrian where it abuts against the Lower Keweenawan series over- 

 laps it unconformably. But if, as Leith suggests, it is a land formation, 

 that is exactly what would be expected. It is, however, a moot 

 question of fact, upon which probabilities must be balanced, and 

 I believe that in the forthcoming monograph by Yan Hise and Leith 

 on the Lake Superior region both sides of the question will be fairly 

 put forth, and they will doubtless agree with the writer in saying that 

 it would be dangerous, in making estimates of the age of the earth, 

 to assign to this series of lavas and conglomerates a thickness of 

 50,000 feet or anything like the age-value of a series of limestones 

 and shales. This was recently and quite pardonably done by a 

 writer in the Geological Magazine, who was not acquainted with 

 the local facts. It will be much wiser in such estimates to count it 

 as part of the Cambrian. There are, however, some other questions 



DECADE V. — VOL. V. — NO. XI. 31 



