July 23, 1915. 
Canada 
Geological Survey 
Museum Bulletin No. 18. 
GEOLOGICAL SERIES, No. 28. 
Structural Relations of the Pre-Cambrian and Paleozoic Rocks 
North of the Ottawa and St. Lawrence Valleys. 
By E. M. Kindle and L. D. Burling. 
INTRODUCTION. 
Eastern Canada affords no more striking physiographic 
feature than the scarp-like southern face of the Laurentian 
plateau. This northern rim of crystalline rocks rises generally 
from 700 to 1,000 feet above the broad, comparatively flat 
plain of Palaeozoic rocks and marks their northern limit for 300 
miles along the north side of the Ottawa and St, Lawrence 
valleys (Figure 1). This upland is a large uneven plateau with 
hummocky surface and forms part of the great expanse of 
Pre-Cambrian rocks to which the term Canadian shield 1 or 
Northern Pro taxis has been applied. The Canadian shield 
has an area of about 2,000,000 square miles and an average 
elevation of about 1,500 feet above sea-level. 2 The contact 
between this plateau of Pre-Cambrian rocks and the plain 
of Palaeozoic rocks forms generally a series of nearly straight or 
gently curving lines. 
1 Suess, The Face of the Earth, vol. II, 1906, p. 30. 
2 Frank D. Adams, Problems of American Geology, Yale Univ. Press, 
New Haven, Conn., 1915, p. 47. 
