CHAPTER II 

 THE BASIS OF PRE-CAMBRIAN CORRELATION 



FRANK D. ADAMS 

 McGill University, Montreal 



That was indeed a fair and sunlit earth which our predecessors, 

 the first geologists, had presented to them for study. The uniform 

 strata of the newer periods of our earth's history in their succession, 

 well exposed, and following one another in due and regular order, 

 everywhere contained abundant fossil remains which afforded a cer- 

 tain clue by which correlation could be made even in widely sepa- 

 rated areas. We, their unfortunate successors, in pursuing our studies 

 are obliged to descend into the deeper parts of the earth where the 

 light begins to fail and when once we pass through that last grim portal 

 into the drear pre-Cambrian world, we enter into what these earlier 

 geologists regarded as a hopeless chaos. Here we lose the guiding 

 thread of life, and the darkness deepens. At first we could dimly 

 descrv but the outhnes of the vast indeterminate ruins of former 

 worlds, but as our eyes become accustomed to the darkness these 

 become somewhat more distinct and we recognize succession even 

 in this ruined waste. 



It may be that being a petrographer I overestimate the value of 

 paleontology, but, like other things, we prize it most highly when it 

 is lost and we are obliged to look for something to take its place. The 

 working-out of the stratigraphical succession by detailed map: ing 

 in special areas teaches us much, but unfortunately the areas showing 

 such succession are usually hmited and isolated and the criteria for 

 correlating the successions in separated areas, and especially in widely 

 separated areas, are as yet undiscovered. 



The vice-president of our section, Dr. Bailey Willis, in inviting 

 me to take part in this symposium, has suggested that I should treat 

 this subject of pre-Cambrian correlation if possible on broad lines, 

 and I therefore venture today to follow Faust's aspiration, "Schau' 

 alle Wirkenskraft und Samen," and present a certain aspect of the 



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