230 C. D. WALCOTT — PRE-CAMBRIAN FOSSILIPEROUS FORMATIONS 



largely recom posed from the Huronian deposits. Professor Van Hise 

 thinks that it is not at all certain tliat the trails and markings described 

 by Gresley were not contained in the sandstone accompanying the ore 

 in the Cambrian formation. 



I now have before me the specimens described by Mr Gresle}^, and it 

 is my judgment that, so far as any of the lithological characters of the 

 matrix can indicate, the specimens were more probably derived from tlie 

 unaltered Cambrian sandstones than from the more or less altered Hu- 

 ronian sandstone. 



In view of this and Professor Van Hise's statement of the occurrence 

 of iron ores in the Menominee district in the Cambrian, I think that we 

 are not warranted in accepting the trails and markings as evidence of 

 life in the pre-Cambrian rocks of the Lake Superior region. 



In a paper discussing a supposed fossil from the copper-bearing rocks 

 of lake Superior * Dr M. E. Wadsworth states that in his opinion the 

 specimen is of inorganic origin, probably a "simulative lava flow." 



The evidence of life in the Animikie rocks consists of the presence of 

 graphitic material in the slates and of a supposed fossil mentioned by 

 Mr G. F. Matthew, f 



Professor Van Hise defines the Upper Huronian as a gently folded 

 series of strata formed of conglomerates, quartzites, shales, slates, mica- 

 schists, ferruginous beds, interbedded and cut b}'^ greenstones, the whole 

 having a maximum thickness of at least 12,000 feet. In this series are 

 included the Minnesota and Dakota quartzites. J He mentions the oc- 

 currence in the Minnesota quartzites of Lingula-like forms, as well as an 

 obscure trilobitic-looking impression described by Winchell. § The lat- 

 ter I have examined carefully and have concluded that it is of inorganic 

 origin. The Lingula-like forms are so obscure that it is difficult to tell 

 whether they are of organic origin or not. The weight of evidence is in 

 favor of their being small flatteaed concretions that in some specimens 

 have the appearance of a crushed Obolus or Acrothele. 



NEWFOUNDLAND AVALON TERRA NE 



Fossils. — The Aspidella of the Momable slates of Newfoundland is 

 probably of organic origin, but it ma}'^ be questioned. It appears to be 

 impracticable to ascertain what the Arenicolite-like fossil is that Mr E. 

 Billings mentions as associated with Aspidella. No specimens are known 



*Proc. Boston Soc. Nat. Hist., vol. xxiii, 1884, p. 208. 



t Careful study of the specimen sent to Mr G. F. Matthew by Dr A. R. C. Sehvyn leads to the con- 

 clusion that the markings attributed to organic agencies are probably of inorganic origin. A pho- 

 tograpli of the slab of slate is given on plate xlvi of Monograph xxx, U. S. Geol. Survey. 



X Bull. U. S. Geol. Survey, no. 80, p. 499. 



g Fossils from the red quartzite at Pipestone. Geol. and Nat. Hist. Survey, Minnesota, Thirteenth 

 Ann. Report for 1884-1885, pp. 65-72. Describes Linqnla calumet and Paradoxkles barberi. 



