THE BASIS OF PRE-CAMBRIAN CORRELATION.! 
ish 
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 
descry but the outlines 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 mapping 
in special areas teaches us much, but unfortunately the areas showing 
such succession are usually limited 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, ‘‘Schaw’ 
alle Wirkenskraft und Samen,” and present a certain aspect of the 
t Read before Section E of the American Association for the Advancement of 
Science, December, 1908. 
105 
