474 TRANSACTIONS OF SECTION C. 
fossils and a more or less considerable amount of metamorphism, they scarcely 
differ in character from later formations. They include great thicknesses of 
conglomerate arkose, quartzite and slate, evidently laid down by water; and 
the Lower Huronian basal conglomerate has all the features of boulder clay 
formed by a great ice-sheet. The extensive development of limestone and 
carbonaceous slate suggests life. The eruptive rocks found with the Kee- 
watin and Huronian sediments are mainly of surface volcanic origin, lava 
streams and ash rocks. 
If the oldest known rocks are of the character just stated, the evidence for 
uniformity in the world’s history is very strong. There is no geological proof 
that the earth was hotter in the earliest times than at present; so that the 
common form of the Nebular Hypothesis receives no support from geology, 
2. The Pre-Cambrian Rocks of Canada. By Professor W. G. Muuirr. 
At the Toronto meeting in 1897, Dr. George M. Dawson, in his Presi- 
dential Address to Section C, summarised the knowledge of the Canadian 
pre-Cambrian. Since that time considerable progress has been made in 
deciphering the history of these ancient rocks. In 1904 an international 
committee, consisting of representatives of the United States and Canadian 
Geological Surveys, visited typical areas on both sides of the international 
boundary in the Lake Superior region. In 1906 a similar committee 
visited south-eastern Ontario and the Adirondack district in the New York 
State. The result of the work of both committees is that the same system 
of age classification is followed in both countries. The most ancient 
pre-Cambrian rocks, which consist of various voleanic types, greenstone 
now being the most characteristic, is known as the Keewatin. This volcanic 
series is cut through by granite and gneiss, to which the name Laurentian 
is applied. The Keewatin-Laurentian complex represents in Canada the 
Lewisian of Britain. After the intrusion of the Laurentian into the 
Keewatin, both were subjected to long-continued erosion, giving rise to 
conglomerates, greywackes, quartzites, arkoses, &c., now classed as 
Huronian. Three divisions, separated by unconformities, are recognised 
in the Huronian (Lower, Middle, and Upper or Animikie). The Huronian 
and Keweenawan may be said to correspond to the Torridonian of Scotland. 
A series of conglomerates, sandstones, and marls, cut by great sills of 
trap, overlie the Huronian in the Lake Superior region. This series is 
known as the Keweenawan, and was classed as pre-Cambrian by the Inter- 
national Committee, although some workers in the field are inclined to 
group it with the Cambrian. 
The following table , shows the age classification of these rocks in 
descending order now recognised in Central Canada :— 
Keweenawan. 
(Unconformity.) 
| Upper or Animikie. 
1an 
Middle. 
Lower. 
(Great unconformity.) 
Laurentian. 
(Intrusive contact.) 
Keewatin. 
The International Committee of 1906 decided, as did earlier workers, 
that the Grenville and Hastings series are one and the same,°and that 
the term Hastings should be dropped.* 
Other workers in the field hold different views, and believe that the 
Huron 
* Journal of Geology, Chicago, May 1907. 
