STRUCTURAL RELATIONS OF PRE-CAMBRIAN AND PALEOZOIC. 
11 
east of the central Pre-Cambrian area was derived in part 
from the Ottawa and Cornwall (No. 120) and the Grenville 
(No. 121) sheets of the Geological Survey, Canada, and in part 
from new field observations. Southwest of this central Pre- 
Cambrian area the geology was derived from well records. 1 
The vertical scale of the cross-section is such as to greatly 
magnify the dips. The extent of the exaggeration is indicated 
by the statement that the dip west of the central Pre-Cambrian 
area is only 12§ feet to the mile. The more northerly and north- 
easterly province cut by this section clearly represents a zone 
in which faulting is the most striking and characteristic structural 
feature, wfiile the more southerly province lies outside this zone. 2 
It must be noted, too, that the faulting of the Ottawa and St. 
Lawrence plain is localized and apparently confined chiefly to 
its northern portion. This fact was pointed out by Ells, who, 
in speaking of the belt of Palaeozoics bordering the St. Lawrence 
1 Well records used were derived from the following sources, the authors 
being indebted to Mr. Wyatt Malcolm of the Geological Survey for the use of 
his manuscript compilation of the well records of Ontario and Quebec: 
WTiIlby: Brumell, Ann. Rept. Geol. Surv., Canada, Vol. V, 1893, p. 24Q. 
Highland Creek: Brumell, loc. cit., p. 24Q. 
York township, lot 11, con. Ill: Ingall, Ann. Rept. Geol. Surv., Canada, 
Vol. V, 1893, p. 107 SS. 
Toronto: Brumell, loc. cit., p. 25Q. 
Swansea: Brumell, loc. cit., p. 25Q. 
Mimico: Brumell, loc. cit., p. 26Q. 
New Toronto: Ingall, Ann. Rept. Geol. Surv., Canada, Vol. VI, 1895, 
p. 109S. 
Clarkson: Files of Water and Borings Division, Geol. Surv., Canada. 
Hamilton: Coste, 15th Rept. Bur. Mines, Ontario, 1906, p. 112. 
Dundas: Brumell, loc. cit., p. 31Q. 
Brantford: Coste, loc. cit., p. 112. 
Beachville: Files of Water and Borings Division, Geol. Surv., Canada. 
St. Thomas: Depth only record available. 
* It may be noted here that Wilmott (Jour. Geol., vol. XI, 1900, pp. 40, 
42) has inferred the existence of a fault extending from the southeastern 
border of the Adirondacks to the northern end of Lake Nipigon. Since, how- 
ever, the author of this paper disclaims personal familiarity with the south- 
eastern part of the region traversed by this fault and presents no specific 
evidence for its existence in the district northwest of the head of the St. Law- 
rence, the only part of its course with which we might be concerned in this 
paper, it has not seemed advisable to include it in the present discussion. 
In this region the field evidence seems to be decidedly against the existence 
of such a fault. For a discussion of the effect of local faulting around the east- 
ern borders of the Adirondack region the reader is referred to papers by Prof. 
J. F. Kemp and Prof. W. M. Davis (Popular Sci. Monthly, Mar. 1906; Science, 
vol. XXIII, 1906, pp. 630-632, 
