16 
MUSEUM BULLETIN NO. 8. 
slate conglomerate, were, as a rule, easily recognizable in suc- 
cessive areas, although the independent use of this criterion has 
led in the past to the confusion of three different limestone for- 
mations which occur in or near the Original Huronian district. 
In most cases it was found possible to check the identity of 
lithologically similar formations in different areas by determining 
whether they were preceded or followed in each case by similar 
successions of other formations. 
The areas studied were chosen mainly with a view to ob- 
taining complete successions of the Huronian sediments and 
reliably correlating these. It was soon found that such areas 
were apt to be correspondingly poor in pre-Huronian sedimentary 
rocks and that an equally good correlation of the latter involved 
the selection and study of a second chain of areas containing 
good pre-Huronian successions. Consequently the following 
correlation is tentative and incomplete for the pre-Huronian 
sediments and the igneous rocks associated with them. 
The principal subdivisions are considered in ascending order 
as follows: — 
The Pre-Huronian, 
The broad relationships existing between the pre-Huronian 
rocks in each of the areas under discussion, are summarized 
below: — 
Bruce. 
Granite-gneiss (Killar 
ney) 
Irruptive contact 
Green schists 
Espanola. 
Metamorphic sedi- 
ments (Sudbury 
series ?) 
Blind River. 
Granite-gneiss (Kil- 
larney) 
Irruptive contact 
Metamorphic sedi- 
ments. 
Round Lake. 
Granite-gneiss 
Irruptive contact 
Copper Cliff arkose 
(Sudbury series) 
Whiskey Lake. 
Granite-gneiss (Kil- 
larney ?) 
Irruptive contact 
Slate 
Green schists 
Wanapitei. 
Granite-gneiss (same . 
as at Round lake) 
Irruptive contact 
Copper Cliff arkose 
(Sudbury series) 
Green schists 
