i 
238 A. P. COLEMAN—CLASTIC HURONIAN ROCKS. 
and have afterward been disinterred by long continued denuding forces. 
Good examples of wide areas of granitoid rocks, merging at many points 
into gneiss and having an eruptive contact with the overlying rocks, are 
to be found, according to Dr Dawson, in the Coast ranges and interior 
plateau of British Columbia,* but here the Basal Complex is of Jurassic 
age. 
CONCLUDING OBSERVATIONS 
It will be observed that the term Laurentian has been employed in 
this paper as Lawson and other Canadian geologists are accustomed to 
employ it, in a petrographical and structural sense for crystalline gneissic . 
or Sranitic rocks underlying the Huronian. That these rocks have con- 
solidated at a later time than the Huronian is evident, and therefore 
they have not the position in time which Logan supposed when the 
hame was given. It may be advisable to provide another designation 
for these widespread rocks, which occupy the same position structurally 
and are formed of practically the same materials as those to the south, 
whose attitude with reference to the Huronian Goniesipomes to Logan’s 
original Huronian. 
How much of the 2,000,000 square miles of the Canadian Archean 
presents the same relationships as have been described in this paper, 
and how much shows the orthodox unconformity between Huronian 
and Laurentian can be determined only by careful field work. If the 
eruptive contact is the normal type and the Huronian which rests dis- 
cordantly on the Laurentian turns out to be really later in age than Law- 
son’s Ontarian, we must look on the Couchiching series as presenting the 
oldest known rocks. This would carry back the ordinary sedimentary 
deposit of sands and clays to the beginning of known geological time. 
*Geol. Survey of Canada, 1886, part B, and 1894, part B. 
