PRE-CAMBRIAN OF NORTHERN ONTARIO AND QUEBEC 329 



granites intrusive into the Middle Huronian but underlying the 

 Upper Huronian or Animikie/ The transfer of this term to 

 Timiskaming district 500 miles to the east was made upon a 

 correlation of the Cobalt series with the Animikie, since both 

 series are flat lying and overlie a great unconformity, and a 

 secondary decision that the Timiskaming, as a folded sedimentary 

 series lying beneath the Animikean, was probably Lower Huronian. 

 But with the determination of the Timiskaming series as pre- 

 Huronian in age, while the intrusive granites are found in the Lake 

 Huron area to underlie the Bruce or Lower Huronian, it is clear 

 that the use of the term Algoman is entirely unjustified. 



In its place the writer would apply the term Laurentian to these 

 granites. This much-abused term has had an eventful history. 

 It was first applied by Sterry Hunt in 1852 to what had up to then 

 been known as the Metamorphic series, or lower pre-Cambrian. 

 At that time these rocks were supposed to be all sedimentary, on 

 the grounds that their gneissic textures were the remains of original 

 bedding. They had been described in 1847 ^s consisting of a lower 

 group of reddish and grayish syenitic gneisses, much contorted and 

 generally at high angles, succeeded by an upper series containing 

 important beds of crystalline limestone interstratified with the 

 syenitic gneiss. The two groups were considered to be conform- 

 able. Between 1862 and 1865 the Laurentian, still supposed to be 

 all sedimentary, was further subdivided into the Upper Laurentian, 

 Labradorian, or Norian, in which subdivision were placed the great 

 anorthosite bodies in the vicinity of Montreal, and the Lower 

 Laurentian, which was further subdivided into the basal Ottawa 

 Gneiss and the overlying Grenville series of interbedded crystalline 

 limestones, quartzites, and gneisses. One of the first suggestions 

 that part of these rocks might not be sedimentary but intrusive 

 seems to have come from A. R. C. Selwyn, in the Summary Report 

 of the Geological Survey Canada for 1877-78, but the first definite 

 conclusion in this regard drawn from field observation is by Vennor, 

 who reported in the director's Summary Report of the Geological 

 Survey of Canada for 1879-80 that some of the anorthosites north 

 of the St. Lawrence appeared to be intrusive in the crystalline 



^Gcol. Siirv. Can. Mem. No. 40, p. 82. 1913. 



