No. 4.] SPENCER — SURFACE GEOLOGY. 215 



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 escarpment 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 Gr. W. Railway station, at Dundas, the trend of the range 

 bends more to the northward, and from this point there is a 

 marked differeuce in the configuration of the country below the 

 summit. The range, after extendiag beyond Waterdown, turns 

 still more to the northward and passes near Milton and Lime- 

 house 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 to within four feet of the surface). At Water- 

 down 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. Farther to the northward the 

 country rises until it reaches ao altitude of 1462 feet above Lake 

 Ontario, or 1709 feet above the sea, near Dundalk station, on 

 the W. G. & B. Railway. The features of the surface of the 

 country above the highlands north of Dundas are much more 

 varied than south of Dundas valley. As the trend of the escarp- 

 ment turns northward around the end of the lake, the f:)ce of the 

 slope looks towards the eastward. 



Basin of Lake Ontario.''^ — As is well known, Lnke Ontario 

 consists of a broad shallow (considering its size) basin, excavated 



* The various Canadian railways and canals, whose elevations are 

 referred to sea level, take Lake St. Peter as the datum. This repre- 

 sents high tide in the St. Lawrence River. The elevation assigned to 

 Lake Ontario is 235 feet (by the Grand Trunk Railway) and 232 feet, 

 according to different Canadian authorities, (above Lake St. Peter). 

 The U. S. Lake Survey places Lake Ontario at 246-91 feet, and Lake 

 Erie at 573-60 feet above mean tide. The Wei land Canal places Lake 

 Ontario at 326-75 feet below Lake Erie (which is now generally 

 acknowledged to be 573 feet above mean ocean level). Therefore in 

 all future references to elevation above mean tide, I have taken Lake 

 Ontario at 247 feet. 



