PRE-CAMBRIAN FORMATIONS— ONTARIO AND MANITOBA 471 



1. In the early part of the pre-Cambrian, periods of volcanic 

 activity alternated with periods of normal sedimentation. The 

 resulting rocks form one great series. 



2. At present local terms only should be used in subdividing 

 this complex. The terms now in use in the generalized classifica- 

 tions are inapplicable, and should be restricted to the areas in 

 which they were used originally. 



3. The sedimentary record of the early pre-Cambrian seems 

 to be largely one of continental rather than marine conditions. 

 Some of the deposits were undoubtedly deltaic, others were likely 

 piedmont, lacustrine, fluviatile, and even basin deposits. It 

 points to the conclusion that even from the very earliest pre- 

 Cambrian, the Canadian shield was a positive element. 



