ROO RNAL OF GEOLOGY 
LL DOES SI RAN OVE, 
THE SIGNIFICANCE OF RECENT DEVELOPMENTS IN 
THE PRE-CAMBRIAN STRATIGRAPHY OF THE 
LAKE SUPERIOR-LAKE HURON REGION 
MORLEY E. WILSON 
Geological Survey, Ottawa 
INTRODUCTION 
The geological investigations carried on during the last decade 
in the northern parts of the Canadian provinces of Ontario and 
Quebec have added much to our knowledge of the pre-Cambrian 
terranes of that region, notably so in the Lake Timiskaming 
district, where the discovery of the silver-bearing veins at Cobalt 
and of the auriferous quartz lodes at Porcupine has led to extended 
exploration in the adjoining country. And it is now generally 
accepted that the pre-Cambrian rocks of northwestern Quebec and 
northeastern Ontario fall naturally into two strikingly different 
divisions, separated by a most profound (pre-Huronian) erosion 
interval. It is also possible, as will be shown in the following 
pages, that the ancient peneplain or paleoplain formed during 
this interval, was continuous with the pre-Animikie or Eparchaean' 
erosion plane which occurs in the region north and west of Lake 
Superior, and that the so-called Lower or Lower-Middle Huronian 
sediments found in the same locality are in reality a part of the 
basement complex and pre-Huronian in age. 
t A.C. Lawson, Bull. Univ. of Cal., III, 50-62. 
Vol. XXI, No. 5 385 
