Spencer.j Ou4: [March 18, 



ilton and North Western Railway reaches the summit, the altitude above 

 Lake Ontario is 493 feet. At Carpenter's quarry, two miles southward of 

 the "mountain" brow, at the head of James street, the altitude reaches 

 485 feet ; and near Ancaster the summit is 510 feet above Lake Ontario. 

 From eastward of Grimsby (for twenty miles) to near Ancaster, the es- 

 carpment presents an abrupt face from 150 to 250 feet below the summit 

 (having a moderate amount of talus at the base), thence it extends by a 

 more or less steep series of slopes to the plane, which gradually inclines 

 (sometimes by a succession of terraces), to the lake margin. 



On the northern side of the town of Dundas, the abrupt face of the es- 

 carpment looks southward, and extends four or five miles westward, until 

 the exposure becomes covered by the drift deposits near Copetown station, 

 similar to the termination at Ancaster on the south side of the Dundas 

 valley, but not by an abrupt ending as at the latter locality. About two 

 miles east of the G. W. Railway station, at Dundas, the trend of the range 

 bends more to the northward, and from this point there is a maii?;ed differ- 

 ence in the configuration of the country below the summit. The range, 

 after extending beyond Waterdown, turns still more to the northward and 

 passes near Milton, and Limehouse station (on the G. T. Railway), 

 and thence extends to Georgian bay.* The height of Copetown above the 

 lake is 502 feet. On the west side of Glen Spencer it is 409 feet, and east- 

 ward of the same gorge the highest point is 520 feet (Niagara limestone 

 coming within four feet of the surface). At Waterdown the altitude is 

 over 500 feet (?) and at Limehouse the brow of the range (though only the 

 lower beds of the Niagara limestones occur) is 810 feet. The features of 

 the surface of the country above the highlands north of Dundas are much 

 more varied than south of the Dundas valley. As the trend of the es- 

 carpment turns northward around the end of the lake, the face of the slope 

 looks towards the eastward. But the country does not present the steep 

 declivities as exhibited along the southern side of Lake Ontario ; for the 

 vertical face is usually less than 100 feet, and the countr^'^ between it and 

 the water has a more uniform pitch. 



Basin of Lake Ontario. As is well known. Lake Ontario consists of a 

 broad, shallow (considering its size) basin, excavated on the southern 

 margin out of the Medina shales, and having its southern shores from one 

 to several miles from the foot of the Niagara escarpment. The Medina 

 shales form the western margin (where not covered with drift) to a point 

 near Oakville. From this town to a point some distance eastward of Toronto, 

 the hard rocks are made up of the different beds of Hudson River Epoch ; 

 while the soft Utica shales occupies the middle portion, and the Trenton 

 limestones the portion of the Province towards the eastern end of the 

 lake. 



The country at the western end of the lake consists of slopes gently rising 

 to the foot of the Niagara escarpment, noticed before. Sometimes this ele- 

 vation is by terraces, and again by inclines so gentle, as between the foot of 

 the escarpment at Limehouse (on the G. T. Railwa}') and the lake, where 



