118 A FOPULAR EXPOSITION OF THE 
the anorthosite of the township of Abercrombie:in the county of Terre- 
bonne, in those of Morin and Mille-Isles, and in some of the boulders 
met with in the Ottawa district. 
2. Structure of Laurentian rocks :—These rocks, as a general rule, 
occur in inclined beds—the dip varying from eight or ten to over 
seventy degrees. The direction of the dip is extremely variable, as 
the strata are not only inclined, but are folded more or less into a 
series of anticlinals and synclinals. In some beds, both of gneiss and 
limestone, the subordinate layers are much contorted, as shown in 
the annexed figure, sketched on Crow Lake, north of Marmora; 
and the same peculiarity is seen in 
HH many other localities. Between the 
OM. Cr Laurentian strata and the Silurian 
beds which rest upon them in Eastern: 
and the greater part of Western 
Canada (the Huronian being absent), there is always a want of con- 
formability. Along the line of junction of the two formations, between 
the eastern extremity of Lake Ontario and the east coast of Georgian 
Bay, the Laurentian strata appear to dip very generally towards the 
north, that is, between N.W. and N.E., or away from the Silurian beds: 
—as shown in the accompanying section, taken on Lake St. John in. 
the township of Rama, C. W. ‘The dotted line in this section shows 
Fig. 152. 
a 
Fig 153. 
the ordinary level of the lake. The Laurentian strata have a general 
northerly dip also, near the junction line of the two formations in the 
township of Elzevir, and at other points visited by the writer; but this 
does not apply everywhere, as on Loughborough and Crow Lakes the 
dip is SE. or nearly so; neither does it continue apparently for any 
great distance to the north, the dip rapidly changing with the foldings 
of the strata. The Sketch-section on a previous page (fig. 151), im 
which an attempt is made to convey an idea of the foldings of the 
Laurentian strata generally, will render this sufficiently clear. 
8. Intrusive Rocks :——Considering the immense extent of country: 
occupied by the Laurentian rocks, intrusive masses of contempora- 
