136 G. 7?. Van Hise — Lake Superior Stratigraphy. 



able amount. Also small quantities of rock may even be ob- 

 tained which will burn. These substances must result from 

 the ordinary processes which produced rock gas and coal in the 

 rocks of far later age. In the Sioux quartzites one unquestion- 

 able fossil has been discovered by Professor X. H. Winchell :* 

 a discovery of a fossil has been announced by Dr. Selwynf as 

 occurring in the Animikie, It is a hope that in the future 

 numerous other fossils will be found in these series, so that we 

 may have the assistance of paleontology in Lake Superior 

 stratigraphy. Until, however, a fauna is known in this 

 region which is distinctly Cambrian, the discovery of life or 

 of certain fossils in the Keweenawan and Huronian rocks is 

 wholly insufficient evidence for placing them with the Cam- 

 brian. The Cambrian fauna in development is fully half way 

 up the life column. Just as another period of life has suc- 

 ceeded the Cambrian, another has preceded it. The progress 

 of paleontological knowledge has of late been downward. 

 Before there was a recognized Cambrian there was a well 

 known Silurian, and it is probable that as we become familiar 

 with all parts of the world, other faunse will be discovered 

 below the Cambrian as distinctive in character as the Cam- 

 brian is from the Silurian. "When this is done, we shall have 

 definite means to correlate rock series which occur in different 

 parts of the world in the great time place represented by the 

 Algonkian.^; 



I have no expectation that the above provisional succession 

 and correlation for the Lake Superior region will prove to be 

 accurate in all details. To a certain extent it is based upon a 

 large number of facts and may be considered as true with a 

 reasonable degree of probability. Another part is based upon 

 facts of a more general nature and therefore has a correspond- 

 ing uncertainty. It is. however, believed that there is in 

 reality a much greater degree of harmony than has been 

 thought in the conclusions which the various writers have held 

 most steadfastly as to Lake Superior stratigraphy. 



* GeoL and Nat. History Survey of Minn.. 13th Annual Report. 1884. pp. 6S-12. 



f Tracks of Organic Origin in rocks of the Animikie group. A. E. C. Selwyn: 

 this Journal. III. xxxix. 145-147, 1890. 



\ For a fuller discussion of the subject of this paragraph see " On the Classifi- 

 cation of the Early Cambrian and Pre-Cambrian Formations."* R. D. Irving. U. S. 

 Geol. Survey. 7th Ann. Kept, pp. 448-454. 



