390 SECTIONAL TRANSACTIONS.—C. 
(e) Prof. T. T. Quirkp.—UCorrelation of the Huronian and Gren- 
ville Rocks of South-Eastern Ontario. 
Current hypotheses of correlation are applied to the north shore district 
of Lake Huron. Lawson’s classification, based on the times of Laurentian and 
Algoman granites, does not apply. The younger granite in this area is of 
so-called Keweenawan age, known by the local name Killarnean. 
H. C. Cooke has traced Grenville sedimentary schists across granite batholiths 
into the Nemenjish series of north-western Quebec; he ccncludes both are very 
much older than the Huronian series. In south-eastern Ontario Grenville rocks 
are not older than the Huronian series. 
Recent discoveries near Killarney indicate that the Huronian series are iden- 
tical with certain contact metamorphosed sediments previously called Grenville, 
and that many other occurrences of sedimentary schists and intruding granite, 
now mapped as Grenville and Laurentian, will be shown ta be Huronian and 
Killarnean. The evidences described concern : (1) Huronian sediments included 
within granite gneisses between the Huronian areas and Grenville areas; (2) the 
persistence of the structure characteristic of the Huronian terrane into the 
region of Laurentian and Grenville rocks; (3) the fact that Keweenawan quartz 
diabase near Killarney is contact metamorphosed into amphibolites similar to 
those described in the Haliburton-Bancroft area, and the fact that in nearly 
all the north-eastern Pre-Cambrian regions not intruded by Killarnean granite, 
there are quartz diabase or similar dykes, whereas there are none recognised in 
the Grenville areas. This implies that such Grenville rocks are intruded by a 
granite younger than Keweenawan diabases and probably the same in age as 
that at Killarney. 
(g) Prof. R. C. Watitace.—Some Types of Mineralization in the 
Pre-Cambrian Rocks. 
(h) Dr. Ettswortu.—Radioactive Minerals as Age Indicators in 
Geology. 
A critical discussion of the method of measuring geological time by atomic 
disintegration. Many problems are involved, including apparent lack of con- 
cordance of certain results. The importance of exact chemical analyses. Owing 
to the limitations of analytical methods at present, non-concordance of results 
may be due to experimental errors in some cases. Radioactive minerals prob- 
ably are of much more common occurrence than is generally supposed. The 
relative values of such minerals as age indicators depend on their chemical 
composition, quantities obtainable, and frequency of occurrence. Possibilities 
of concentration from rocks. Recent Canadian work. Canadian radioactive 
mineral occurrences afford favourable conditions for testing the reliability of 
the method. 
(1) Prof. A. P. Coueman, F.R.S.—Pre-Cambrian Climates. 
The belief once current among geologists that the earliest Pre-Cambrian 
rocks represented the original crust of the earth, formed as it cooled from a 
molten to a solid condition, has long ago been given up, and evidence is growing 
that climates and geological processes in those early times were not widely 
different from those of later times. 
Passing downwards from the base of the Cambrian in Canada the Keweenawan 
includes red sandstones suggesting desert conditions; the Animikie, with grey 
carbonaceous slates, was probably a time of cool, moist climate; and the 
Huronian, including the Cobalt tillite, was a time of glaciation. 
Below this, after a profound break, is the Sudbury or Timiskaming series, 
mostly of water-deposited materials, including 4,000 ft. of well-banded gray- 
wacke and slate, evidently of seasonal origin. ‘This gritty but well-stratified 
material and some boulder conglomerates make one suspect a cold and perhaps 
glacial climate. 
After another great unconformity the Keewatin and Grenville series, with 
carbonaceous slate and thick beds of limestone, suggest conditions not very 
different, from the present. The thousands of feet of boulder conglomerate in 
the Doré series are thought by some to be torrential deposits, but might equally 
well be accounted for as glacial. 
