380 



THE AZOIC BYSTEM AND ITS SUBDIVISIONS. 



In the Report of the Geological Survey [of Newfoundland] for the 

 year 1872, Mr. Murray notes the discovery of fowsil forms in the Huro- 

 nian rocks of St. John's, which, according to him, "■ appear to mark out a 

 particular zone or horizon of the formation, which is limited to the sub- 

 division {(l) of No. 2 Section " of the Report for 1868. These fossils are 

 the Aspidella (misprinted Aspidilla throughout the report for 1872) 

 Terranovica and the Arenicolites spiralis, described by Billings in the 

 " Palsoozoic Fossils" of the Canada Geological Survey, Vol. 11. Part I. 

 pp. 76, 77. The presence of the Aspidella was considered by Mr. Mur- 

 ray as being of " marked value as an indicator of the horizon, no form 

 bearing any resemblance to that fossil having ever been recognized in 

 the rocks of the upper series. Nor are they known to exist iu any of 

 the strata, by which the slates {d) are underlaid." {I. c, p. 17.) 



In the Report of Progress [of the Geological Survey of Newfoundland] 

 for the year 1873, the presence of " labradorite and other anorthosites" 

 in the gneissic rocks of certain locahties is said to " give rise to the 

 supposition that they belong to the upper or newer Laurentian Series," 

 while angular boulders and fragments of white crystalline limcstoue arc 

 considered to be " suggestive of the proximity of the upper members of 

 the lower series." This is the first intimation that the Laurentian is to 

 be divided into two or more groups, and seems to be merely an endeavor 

 to correlate the older formations of Newfoundland with those of Canada, 

 on a purely mineralogical basis, and on extremely imperfect evidence. 



That certain stratified rocks are unconformable with a lower granitic 

 and gneissic formation, called Laurentian, is evident from the facta 

 stated in the Newfoundland reports. That these strata belong to the 

 Primordial or Potsdam division of the Lower Silurian is also made ap- 

 parent by the character of the fossils which they contain. That these 

 Primordial rocks may be developed to a very great thickness is also ren- 

 dered probable; although it is- not unlikely that a more thorough study 

 of the region would considerably reduce that amount, the region being 

 one difficult of exploration, much disturbed, and largely covered by 



superficial detritus. 



In the Report of Progress [of the Geological Survey of Newfoundland] 

 for the year 1881, the discovery of the Aspidella and the Arenicolites is 

 again alluded to, as offering " great facilities for the ready recognition of 

 the Huronian when tracing out the structure which, otherwise, would 

 be extremely difficult." The value of the evidence based on the pres- 

 ence of these supposed fossils, as establishing a new system between th( 

 Primordial and the LaurentianJ will be discussed farther on. At pres- 



