66 RELICS OF PRIMEVAL LIFE 



the next system in descending order is that to 

 which Logan long ago gave the name Huronian, 

 from its development on Lake Huron ^ — a name to 

 which it is still entitled, though there may, perhaps, 

 be some grounds for dividing it into an upper and 

 lower member.2 Xo this sub-division, however, we 

 need not for the present give any special attention. 

 In the typical area of Lake Huron the Huronian 

 consists of quartzites, which are merely hardened 

 sandstones, of slates which are muddy or volcanic-ash 

 beds, of conglomerates or pebble-rocks, and of coarse 

 earthy limestone. With these rocks are deposits 

 of igneous material which represent contemporary 

 volcanic eruptions. In other districts, as in New 

 Brunswick, Newfoundland, etc., the beds have been 

 considerably altered, and are locally more mixed 

 with igneous products. The physical picture pre- 



^ Dr. G. M. Dawson, F.R.S., the present Director of the Geo- 

 logical Survey of Canada, whose judgment in this matter should 

 be of the highest value, holds that the original simple arrange- 

 ment of Logan still holds, notwithstanding the multitude of 

 new names proposed by the Western Geologists of the United 

 States. 



2 Van Hise, " Pre-Cambrian Rocks of North America." 

 Comptes RenduSy 5th Session International Geol. Congress 

 J891, p. 134. Also "Report U.S. Geol. Survey, 1895." 



